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Medicine Year 3 > Week 6 - Microbiology and Infection > Flashcards

Week 6 - Microbiology and Infection Flashcards

1
Q

Which antibiotics should generally be used in severe/life-threatening infections?

A

Usually IV combination Rx (Beta lactam + gentamicin) initially

Use of protected Abx if risk of MDR

Prompt (<1 hour) administration

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2
Q

Describe the treatment of bacterial endocarditis

A
  • Seek expert opinion on treatment of endocarditis, variety of national treatment guidelines that you can consult
  • Should use bactericidal rather than static drugs, extended therapy of weeks rather than days is required
  • Commonly used regimen for treatment of streptococcal endocarditis (most common cause) of a native heart valve is 4 weeks of benzylpenicillin combined with gentamicin for the first 2 weeks
    • Although streptococci are intrinsically resistant to gentamicin, benzylpenicillin disrupts the cell wall and allows gentamicin to penetrate inside the cell = synergy
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3
Q

Why are CREs important to control?

A
  1. Plasmids can transfer resistance to other stories and species
  2. They can be efficiently transmitted in healthcare facilities
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4
Q

Which type of organism is not covered by any new antibiotics?

A

Opportunisitc gram -ves

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5
Q

How is malaria diagnosed?

A
  • Antigen testing
    • Done in UK - not used to interpreting malaria films
  • Blood films (thick and thin)
    • Thick - confirms presence of parasite, diagnoses malaria
      • Blood onto slide, soluble dye added (lyses red cells), can see parasites
    • Thin - diagnoses the type of malaria
      • E.g. falciparum - cygnet ring/headphone inclusions
  • PCR
    • Usually done after diagnosis
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6
Q

What effect do antibiotics have on the colonic flora?

A
  • Antibiotics dramaticaly alter the colonic flora
  • Most of gut flora wiped out by antibiotics
  • Minority species w/ resistance to antibiotics colonises gut
  • Even after 2 years lack of gut flora diversity - susceptibility to C diff
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7
Q

What is the first choice of antibiotic in a complicated UTI?

A

Ciprofloxacin - higher risk of deterioration in complicated if treatment isn’t effective, resistance less common with ciprofloxacin

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8
Q

How should blood cultures be taken when dealing with a patient with possible bacterial endocarditis?

A
  • 3 sets of blood cultures
  • Taken from peripheral veins
  • 10 mls of blood in each bottle
  • 1 hour between first and last samples
  • Meticulous sterile technique
  • Taken prior to antibiotics
  • Bacteraemia always present - no need to wait for fever, all/majority of cultures should be positive
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9
Q

Describe the pathogenesis of bacterial pneumonia

A

Normally -

  • Lungs constantly exposed to pathogens, well-evolved protection mechanisms - innate and acquired immunity
  • Below level of carina should be sterile (leads to gas exchange)

Pathogenesis of Pneumonia (consolidation of lung):

  • Defect in host defence - immunosuppressed individuals, smokers (destroy macrophages)
  • Large inoculum e.g. inhaled particles in air when infected individual coughs
  • Increased virulence of pathogen - evades immune system
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10
Q

What is the aim of empirical antibiotic guidelines?

A

Promote efficacy and prudency

Protect rather than restrict antibiotics

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11
Q

Give an example of how antibiotic use can lead to antimicrobial resistance

A
  • Co-amoxiclav
  • Amoxicillin has some activity against gram positive organisms and anaerobes
  • Addition of clavulanic acid strengthens activity against anaerobes and gram-negatives by mopping up the beta-lactamase produced by these organisms resulting in higher amoxicillin concentration at the site of infection
  • If target (infection causing agent is streptococci) and co-amoxiclav is used, the collateral damage will be that anaerobes, coliforms etc. are wiped out
  • Sensitive organisms are wiped out, leaves resistant organisms to overgrow
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12
Q

Which groups are most commonly affected by haemophilus influenzae?

A
  • Older people
  • Underlying lung disease
    • Disturbed lung architecture - COPD, pulmonary fibrosis, cystic fibrosis
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13
Q

List the important predisposing risk factors for septic arthritis

A

Elderly

Pre-existing joint disease

Recent joint surgery or injection

Skin or soft tissue infection

Intravenous drug use

Indwelling catheters

Immunosuppression (including diabetes)

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14
Q

Describe methods of bite avoidance

A

Physical Avoidance

  • Indoors
  • AC, screens on doors and windows
  • Impregnated (tucked underneath mattress before sun goes down) netting
    • Permethrin
    • Mosquito free
  • Clothing
    • Cover up (arms, legs, ankles, feet)
    • Spray/soak clothing

Repellant:

  • Deet
    • 30% reapply every 4-6 hours
    • 50% reapply every 6-8 hours
    • Reapply more often if sweating, in water
    • Makes you taste bad to mosquitoes - land but don’t bite
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15
Q

Describe the use of aseptic technique in infection control

A

Reduce activity in area

Keep exposure of a susceptible site to a minimum

Check sterile packs for evidence of damage or moisture

Ensure all fluid materials in date

Do not re-use single use items

Hand decontamination prior to procedures

Protect uniform/clothing with a disposable apron

Use sterile gloves

Appropriate waste disposal

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16
Q

Which antibiotics are considered safe in pregnancy?

A
  • Most beta lactams
    • Broad spectrum agents may be associated with NEC (necrotising enterocolitis) in premature infants
  • Macrolides - respiratory tract infection
  • Anti-tuberculants
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17
Q

What is the clinical significance of pseudomonas bacteria?

A
  • Causes infections in immunocompromised
  • Resistant to many antibiotics
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18
Q

Where are haemophilus bacteria usually found?

A

Inhabit upper respiratory tract, mouth, vagina and intestinal tract

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19
Q

Give examples of other coliforms

A

Klebsiella, Enterobacter

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20
Q

Describe the action of chloramphenicol

A
  • Inhibits the 50S ribosome
  • Excellent broad spectrum activity
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21
Q

Which bacteria are sensitive/resistant to doxycycline?

A

Highly sensitive - streptococcus, staphylococcus

Sensitive - haemophilus, neisseria

Minimally sensitive - enterococcus

Resistant - E. coli and other coliforms, pseudomonas, bacteroides, clostridium

Atypicals also sensitive - Rickettsia, mycoplasma, coxiella, chlamydia, chlamydophia

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22
Q

Is it appropriate practice to use two prescription charts when too busy to rewrite the first chart?

A

Always bad practice to expect nurses to work from two prescription charts

Avoidable clinical risk - things can be missed from the second prescription chart if it is not realised there are two

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23
Q

Which bacteria are sensitive/resistant to ceftriaxone?

A

Highly sensitive - streptococcus, staphylococcus, E. coli, neisseria, haemophilus

Sensitive - other coliforms, bacteroides, clostridium

Resistant - enterococcus, pseudomonas

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24
Q

Which antibiotic would usually be used in cellulitis?

A

Flucloxacillin - provides good cover for common causes

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25
Q

Describe the mechanism of action of antibiotic which inhibit folate synthesis

A

Inhibition of folate metabolism pathway leads to impaired nucleotide synthesis and therefore impaired DNA replication

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26
Q

Describe the toxicity of chloramphenicol

A
  • Very toxic
  • Bone marrow suppression (1 in 10,000 need BMT)
  • Aplastic anaemia
  • Optic neuritis
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27
Q

What are the important non-infectious causes of diarrhoea to consider when a patient presents with acute diarrhoea?

A
  • Acute diarrhoea can often reflect the acute presentation of a non-infectious bowel disease
    • Inflammatory bowel disease (Crohn’s disease/ulcerative colitis), bowel cancer, diverticular disease, chronic pancreatitis, HIV infection and ischaemic bowel
  • Non-gastrointestinal infection can also present with diarrhoea, can be a manifestation of sepsis syndrome (e.g. pneumococcal bacteraemia)
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28
Q

What are the common bacterial pathogens/microorganisms associated with infective endocarditis?

A

Staphylococcus aureus

Streptococci viridans

Streptococcus gallolyticus (S. bovis)

HACEK - haemophilus, aggregatibacter, cardiobacterium, eikenella, kingella

Enterococci

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29
Q

What indicates an uncomplicated UTI?

A

Lower urinary tract symptoms

Absence of sepsis or evidence of upper tract involvement (pyelonephritis)

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30
Q

How is streptococcus pneumoniae treated?

A
  • Penicillin
    • Resistance rare in UK (<1% in Scotland)
    • Beware S. Europe, Asia, N. America - travel history important
  • Allergy (ask what it does to them)
    • Macrolides (clarithromycin)
    • Tetracyclines (doxycycline)
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31
Q

List the bacterial mechanisms for antibiotic resistance

A
  1. Efflux pumps
  2. Decreased uptake
  3. Target alterations
  4. Alternative enzyme
  5. Inactivating enzymes
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32
Q

Which bacteria usually cause UTIs?

A

E. coli, other coliforms

Pseudomonas, enterococcus

Staphylococcus

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33
Q

Describe the appearance of pseudomonas bacteria

A

Rod shaped

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34
Q

What are the commonest causes of jaundice (hyperbilirubinaemia)?

A
  • Gallstones
  • Alcoholic hepatitis
    • Cholestasis with fever and leukocytosis commonly seen
    • Should always be considered in the jaundiced patient with a history of alcohol excess, especially is ratio of serum AST:ALT is greater than 2 with the values being below 500 international unit/L
  • Viral hepatitis
    • Predominantly cholestatic syndrome with marked pruritus
    • A, B, C, D, E, herpes simplex virus, Epstein-Barr virus, CMV
  • Pancreatitis
  • Non-alcoholic steatohepatitis
    • Associated with diabetes mellitus, morbid obesity
  • Primary biliary cholangitis
  • Drugs
  • Sepsis and low perfusion states
    • Bacterial sepsis very often accompanied by cholestasis by hypotension and bacterial endotoxins
    • Congestive heart failure, reduced hepatic blood flow and the delivery of bilirubin to hepatocytes, results in predominantly unconjugated hyperbilirubinaemia
  • Malignancy
    • Paraneoplastic syndromes associated with malignancy can induce a reversible form of cholestasis (Stauffer syndrome), renal cell carcinoma, malignancy lymphoproliferative diseases, gynaecologic malignancies and prostate cancer
  • Liver infiltrations - infiltrative processes such as amyloidosis, lymphoma, sarcoidosis, tuberculosis can precipitate intrahepatic cholestasis
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35
Q

List the symptoms associated with typhoid/paratyphoid fever

A
  • GI symptoms:
    • Diarrhoea vs constipation
      • 50:50
      • Diarrhoea more common in children
    • Abdominal pain - hepatosplenic discomfort
    • Rectal bleeding
    • Bowel perforation - hyperplasia Peyer’s patches
  • Other Symptoms:
    • Neurological
      • Headache (44-94%)
      • Enteric encephalopathy (not infection)
        • Altered consciousness/confusion
        • Increased mortality
        • Steroids
    • Bacteraemia
      • Metastatic infection
    • Relative bradycardia (would expect tachycardia)
    • Rose spots - bacterial emboli to skin
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36
Q

List the reservoirs for infections

A
  • Environment
  • Animals
  • Humans
    • Symptomatic/asymptomatic
    • Carriers
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37
Q

Describe the use of amoxicillin

A
  • Semi-synthetic penicillin
    • Greatly increased activity against gram negative organisms (although resistance is now common)
    • Much more orally bioavailable than natural penicillins
  • Widely used in the treatment of many infections
  • Sensitivities
    • Streptococcus, enterococcus
    • Neisseria
    • Haemophilus, clostridium
  • Resistance
    • Rest
  • Often used for respiratory tract infections caused by strep/haemophilus
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38
Q

Describe the toxicity of gentamicin

A
  • Nephrotoxicity
  • Ototoxicity
    • Hearing and balance loss
    • Oscillopsia
  • Neuromuscular blockage - usually only significant in myaesthenia gravis
  • Strict prescribing to prevent toxicity
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39
Q

List bacterial causes of traveller’s diarrhoea

A

Enterotoxigenic E. Coli

Enteroaggregative E. Coli

Campylobacter sp.

Salmonella sp.

Shigella sp.

C difficile

Vibrio sp.

Aeromonas

Plesiomonas shigelloides

Yersinia enterocolitica

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40
Q

How can antibiotics cause harm?

A
  • Disruption of bacterial flora leads to overgrowth of yeasts (thrush), overgrowth of bowel (diarrhoea)
  • Antibiotic use associated with development of C. diff colitis (in patients and those they are in contact with), future colonisation and infection with resistant organisms
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41
Q

Describe the classification of streptococci

A
  • Initially classified according to their ability to haemolyse blood agar
  • Alpha-haemolytic streptococci
    • S. pneumoniae - also called pneumococcus, common cause of pneumonia and meningitis
    • S. viridans - commonest cause of bacterial endocarditis
  • Beta-haemolytic streptococci
    • S. pyrogenes (group A strep) - can cause wound infections and local infections such as tonsillitis and pharyngitis, as well as serious systemic infections e.g. necrotising fasciitis and fulminant shock with accompanying bacteraemia secondary to infection in other sites
  • Gamma non-haemolytic streptococci
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42
Q

Describe the antibiotic regimen used in the treatment of necrotising fasciitis

A

IV flucloxacillin

IV benzylpenicillin

IV metronidazole

IV gentamicin

IV clindamycin

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43
Q

Which bacteria are sensitive/resistant to tazocin?

A

Highly sensitive - streptococcus, enterococcus, staphylococcus, E. Coli, other coliforms, neisseria, haemophilus, pseudomonas

Sensitive - bacteroides

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44
Q

How are ESBL infections treated? Why is this becoming more difficult?

A
  • Develop a new class beta-lactam antibiotic - carbapenems
  • Carbapenemase now being produced - resistance
  • Carbapenem = broad spectrum antibiotic (related to penicillin e.g. Meropenem)
  • Carbapenemase = an enzyme that breaks down a carbapenem
  • Worrying as carbapenems viewed as the last therapeutic option to treat complex infections caused by MDR bacteria
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45
Q

How are macrolides administered?

A

Excellent oral absorption - given orally even in severe infection

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46
Q

Define sepsis

A

Life threatening organ dysfunction due to a dysregulated host response to infection

Major cause of mortality

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47
Q

Describe the use of benzylpenicillin

A
  • Administered by IV route
    • Oral agent (penicillin V) but not often used
  • First choice antibiotic for serious streptococcal infection e.g. erysipelas - skin
  • Narrow spectrum agent
    • Sensitivities - streptoccocus, some neisseria, minorly clostridium
    • Resistant - others
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48
Q

What is the commonest cause of community acquire pneumonia?

A

Streptococcus pneumoniae

  • Gram positive coccus, in pairs
  • Most common cause in all groups - old, young, immunosuppressed etc.
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49
Q

What is the clinical significance of bacteroides?

A
  • Can cause infections of the peritoneal cavity e.g. after gastrointestinal surgery
  • Resistant to many antibiotics
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50
Q

What are the common causes of cellulitis?

A

Staphylococcus, streptococcus

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51
Q

How can antimicrobial stewardship be incorporated into the concept of realistic medicine?

A

Reduces variation in prescribing practice

Reduces waste - over Rx, redundancy

Reduces harm - CDI, AMR, penicillin allergy, toxicity

Allows personalisation/individualisation - risk based Rx

= optimised use and outcome

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52
Q

How is typhoid/paratyphoid fever treated?

A
  • Quinolones
    • Most effective agents - ciprofloxacin most commonly used
    • Resistance, especially if from South/Central Asia
  • Cephalosporins
    • Empiric therapy
    • Longer courses (14 days)
  • Azithromycin
    • Very good activity with increasing evidence
    • Lack of evidence in severe disease
    • Oral option
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53
Q

List the types of antibiotics which act by inhibiting protein synethsis

A
  • 50S ribosomal subunit
    • Macrolides
      • Erythromycin
      • Clarithromycin
      • Azithromycin
    • Clindamycin
    • Chloramphenicol
  • 30S ribosomal subunit
    • Aminoglycosides
      • Gentamicin
    • Doxycyclin
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54
Q

Describe the appearance of haemophilus influenzae

A

Gram negative rods

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55
Q

What types of infection do carbapenem resistant enterobacteriaceae cause?

A
  • Bacteriaemia
  • Pneumonia
  • UTI
  • Wound infections
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56
Q

Describe empirical guidance in primary care

A
  • Diagnosis usually syndromic and empirical
    • E.g. fever/pain score for bacterial throat infection
  • Near patient tests
    • CRP, GAS test, urinalysis - beware of over diagnosis
  • Culture
    • Skin - only swab infected area - limited value, reflects commensal bacteria
    • Urine culture - asymptomatic bacteriuria
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57
Q

How can the problem of AMR be reduced?

A
  1. Wash hands
  2. Get vaccinated against flu
  3. Improve diagnostic skills
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58
Q

How can C diff infection be prevented?

A

When prescribing keep antibiotics as narrow spectrum as possible

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59
Q

List the types of antimicrobial stewardship interventions used to achieve objectives, and the features of each

A
  1. Persuasive
  • Education, feedback, reminders, specialist advice, lab reporting
  • Longer term benefits through behaviour change
  1. Restrictive
  • Formulary restrictions, pre-authorisation, automatic stop, unsolicited specialist intervention
  • Short term benefits including reduction in resistance
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60
Q

Give examples of haemophilus bacteria

A

Includes H. influenzae which causes sepsis and bacterial meningitis in young child and H. Ducreyi which causes chancroid

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61
Q

Describe how an antibiotic review following empirical treatment is done in primary and secondary care

A
  • Primary care
    • Electronic prescribing of definitive course + decision support
    • ‘Safety netting’ or review to assess response
  • Secondary case - assess response, review patient
    • Clinical, micro results
    • De-escalate - simplify, switch or stop
    • Review IV daily - IVOST/stop
    • Document (3 day) review
      • Record specific duration of Rx
    • Consider specialist input and source control
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62
Q

How can pneumonia be differentiated from an exacerbation of COPD?

A

Consolidation on X-ray or from clinical signs = pneumonia

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63
Q

List the standard infection control precautions

A
  • Assess patients for infection risk and ensure they are cared for in a safe place
  • Practice good hand hygiene
    • 5 hand hygiene moments =
      • Before touching a patient
      • Before procedure
      • After a procedure or body fluid exposure risk
      • After touching a patient
      • After touching a patient’s surroundings
  • Cover nose and mouth when coughing or sneezing (catch it, bin it, kill it)
  • Wear suitable personal protective equipment
  • Keep all reusable care equipment clean and well maintained
  • Keep the care environment clean and tidy
  • Safely handle used linen
  • Safely clean up all blood and body fluid spillages
  • Safely dispose of all household and care activity waste
  • Take corrective action if injured or exposed to blood and body fluids
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64
Q

List the transmission based infection control precautions

A
  • Contact - isolation, cleaning, gloves, apron
  • Droplet - surgical mask and eye protection
  • Airborne - FFP3 masks
    • TB
    • Pandemic flu
    • Aerosol generating procedures for respiratory pathogens
    • Measles varicella zoster
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65
Q

Give examples of beta-lactamase inhibitors

A
  • Clavulanic acid - combined with amoxicillin to make co-amoxiclav (Augmentin)
  • Tazobactam - combined with piperacillin to make tazocin
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66
Q

What measures should be taken in a patient who is found to have a C. difficile infection?

A
  • The severity of the CDI should be assessed and appropriate treatment initiated i.e. a decision made as to whether to start metronidazole or vancomycin
  • Unnecessary antibiotics should be stopped
  • Any laxatives and proton pump inhibitors should be stopped
  • Standard infection control precautions need to be in place as well as isolation of the patient and appropriate hand hygiene with soap and water and not alcohol gels
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67
Q

Describe the typical pathogenesis of acute bacterial cholecystitis

A

Bacterial infection in a patient with biliary obstruction, organisms typically ascend from the duodenum when normal barrier mechanisms are disrupted, bacteria can pass through the sphincter of Oddi with a stone then acting as a nidus for colonisation/infection

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68
Q

How can a rapidly progressing/immediately life-threatening infection be identified?

A
  • Organ dysfunction = sepsis
  • Deep seated/involving vital organs (may not be sepsis)
    • Bacteraemia
    • CNS
    • Cardiovascular
    • Graft related
  • Systemic inflammatory response - fever/hypothermia, tachypnoea, tachycardia, high/low WCC
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69
Q

How does surviellance underpin antimicrobial stewardship?

A
  • Volume of antibiotic prescribing
    • Measured through pharmacy records (not per individual)
    • Stratified for antibiotic type (defined daily dose)
    • Adjusted for population size e.g. per 1000 population or per admission/occupied bed day
  • Quality of antibiotic prescribing
    • Measures prescribing in an individual against a guideline
  • Antimicrobial resistance
  • To inform guidance and monitor effect of interventions
  • Clostridium difficile
  • Other adverse events related to prescribing/interventions
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70
Q

Which bacteria are sensitive/resistant to co-amoxiclav?

A

Highly sensitive - streptococcus, enterococcus, staphylococcus, neisseria, haemophilus

Sensitive - E. coli, other coliforms, bacteroides, clostridium

Resistant - Pseudomonas

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71
Q

What are the important questions to ask when taking a history from a patient presenting with acute diarrhoea?

A
  1. Food history - can they attribute the onset of diarrhoea to a particular meal they ate, classic causes include undercooked poultry, reheated rice and frozen food that has been incompletely defrosted prior to cooking
  2. Ill contacts - many forms of gastroenteritis passes from person to person, particularly important when thinking about viral gastroenteritis where contact with others (often children) with diarrhoea and vomiting is common
  3. Travel history - ask about pre-travel vaccination and food and water precautions when travelling (use of bottled water, ice in drinks etc.), travel to exotic locations increase risk of parasitic causes of gastroenteritis and changes the spectrum of possible pathogens
  4. Past medical history - important when thinking about non-infectious aetiology, ask about medication (many drugs include diarrhoea as a side effect)
  5. Occupational history - some occupations bring people into contact with potential reservoirs of infection e.g. sewage workers, vets. Important to know if they handle food - implications for when they can return to work to prevent onward transmission of any infection
  6. Risk factors for C. diff infection - usually a hospital acquired infection, main risk factors are age >65, recent hospitalisation and recent course of antibiotics (presence of 2/3 risk factors should prompt the consideration of CDI as a cause of diarrhoea)
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72
Q

Describe the reservoir of and illness caused by rotavirus

A

Person to person

Vomiting and non-bloody diarrhoea - most often in children

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73
Q

What criteria define systemic inflammatory response syndrome?

A

2 or more of

  • Temperature >38
  • Tachycardia >90bpm
  • Tachypnoea RR>20/min
  • WBC >12
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74
Q

List antibiotics that act by targetting DNA repair and replication

A
  • Quinolones
    • Ciprofloxacin
    • Levofloxacin
  • Rifampicin
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75
Q

Which antibiotics should be prescribed, and for how long in a hospitalised COPD exacerbation with green sputum?

A
  • Doxycycline or amoxicillin
  • 5 days
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76
Q

How can the action of beta-lactamases be prevented?

A
  • Beta-lactamase inhibitors - effectively inhibit some beta-lactamases
  • Co-administered with penicillin antibiotic
  • Greatly broadens spectrum of penicillins against gram -ves and S. aureus
  • There are many beta-lactamases that are not inhibited leading to antibiotic failure
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77
Q

Describe the typical appearance of streptococci bacteria

A

Gram positive cocci, grow in chains

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78
Q

Describe the minor criteria of the Duke criteria

A
  • Fever - temperature >38
  • Vascular phenomena - arterial emboli, pulmonary infarcts, intracranial bleed, conjunctival haemorrhages, Janeway lesions
  • Predisposing heart condition (prosthetic heart valve or a valve lesion associated with significant regurgitation or turbulence of blood flow) or intravenous drug use
  • Immunologic phenomena - Osler nodes, Roth spots, rheumatoid factor, glomerulonephritis
  • Positive blood cultures but doesn’t meet major criteria or serologic evidence of active infection with organism consistent with IE
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79
Q

Describe the relationship between antibiotic use and antimicrobial resistance

A

AMR correlated with human antibiotics use - countries which use more antibiotics have higher levels of AMR

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80
Q

How is a rapidly progressing/immediately life-threatening infection dealt with in secondary care?

A
  • Urgent blood cultures then IV antimicrobial therapy within ONE hour
  • Review all anatomical systems, perform CXR and consider other imaging/laboratory investigations. Review diagnosis daily.
  • Add cover for S. aureus infection if - healthcare associated, recent hospitalisation, post-op wound/line related, IVDU/PWID
  • Add cover for MRSA infection if recent MRSA carrier or previous infection
  • Add cover for severe streptococcal infection if pharyngitis/erythroderma/hypotension
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81
Q

Describe the type 1 hypersensitivity reaction which can occur in response to beta-lactams

A
  • Relatively common allergy (0.7-4% of penicillin courses)
  • Most patients develop an urticarial rash
  • Anaphylaxis is most feared complication - gross neck swelling and airway obstruction
  • Cross reaction between classes is variable
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82
Q

Describe the appearance of E. Coli

A

Rod shaped coliform

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83
Q

How long should antibiotics be prescribed for in cellulitis, and what is this determined by?

A

7-10 days, determined by response

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84
Q

List the mechanisms of bacterial resistance in gram negative bacteria

A
  1. Loss of porins
  2. Beta-lactamases in periplasmic space
  3. Over-expression of transmembrane efflux pump
  4. Antibiotic modifying enzymes
  5. Target mutations
  6. Ribosomal mutation or modification
  7. Mutations in polysaccharide structure
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85
Q

What is the minimum total duration of antimicrobial therapy recommended for the treatment of septic arthritis?

A
  • Optimal duration remains uncertain
  • Typical duration of parenteral antibiotics is at least 14 days, followed by oral therapy for an additional 7-21 days
  • Choice of oral antibiotic regimen for completion of therapy depends on the pathogen and antibiotic susceptibility (oral agents with high bioavailability)
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86
Q

Explain the staining of gram positive and gram negative bacteria

A
  • Gram positive
    • Stain purple - take up dye and don’t release it when washed due to thick cell wall
  • Gram negative
    • Stain pink - take up dye and release it when washed due to thin cell wall
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87
Q

List the causes of enteric fever (typhoid or paratyphoid)

A
  • Salmonellae typhi
  • Salmonellae paratyphi
  • Human reservoir only (no animal reservoir)
    • Human to human
    • Contaminated food/water
  • Infectious load
    • 1000 organisms cause disease in 10-20%
    • Higher inoculum - shorter incubation period/higher attach rate
  • Most prevalent in South Central Asia - India, Pakistan, Nepal
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88
Q

Why has the use of aminoglyosides recently increased?

A
  • Improved dosing regimens
  • Restriction of other broad spectrum antibiotics e.g. cephalosporins
  • Use of gentamicin in Glasgow more than doubled
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89
Q

Describe the pathogenesis of typhoid/paratyphoid fever

A

Ingest contaminated food/water

Bacteria invade through Peyer’s patches

Infects the reticuloendothelial system - liver, spleen, lymph nodes

After a period of time become bacteraemic

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90
Q

Describe the appearance of emphysema on x-ray

A
  • Black lungs
  • Diffuse hyperinflation with flattening of diaphragm
  • Enlargement of pulmonary artery/right ventricle
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91
Q

What negative effects do mislabeling penicillin allergies have?

A

Increased Rx cost, admission length, AMR and poorer outcomes

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92
Q

What AMR mechanisms have evolved in S aureus?

A
  • Ab degradation - penicillinase
  • Target modification - PBPs (MRSA)
  • Antibiotic efflux - tetracycline R
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93
Q

How long should antibiotics be prescribed for in upper UTIs?

A

7 days

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94
Q

Describe the features of mycoplasma pneumoniae

A
  • Commonest atypical pneumonia - not classical presentation
  • Smallest free living bacterium
  • Lack of cell wall, important when considering antibiotics
  • Very difficult to grow, other ways of diagnosing
  • Most prevalent in autumn/winter
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95
Q

What are the confounding variables affecting resistance of a bacteria?

A
  • Laboratory
    • Inoculum size, growth phase, planktonic, pH, atmosphere
    • Biofilm
  • Clinical
    • Co-morbidities, pus collections, foreign bodies, site of infections
    • Biofilm (e.g. on prosthetics - difficult to treat)
    • Pharmacokinetics
    • Pharmacodynamics
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96
Q

How long should antibiotics be prescribed for in intra-abdominal sepsis and what is this determined by?

A

4 days, determined by if the source is controlled or not

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97
Q

Describe the epidemiology of malaria

A
  • 27-48% hospitalised returning travellers
  • Most common cause of fever in travellers from Sub-Saharan Africa (risk elsewhere)
  • 10% geosentinel no report of fever
    • GI - diarrhoea
    • Respiratory - dry cough
    • Headaches
  • Diagnosis initially missed in up to 59%
  • Rx 7.6 days after admission

High Risk Areas

  • Sub-Saharan Africa
  • India, Pakistan, Southeast Asia
  • Americas - Amazon basin
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98
Q

Describe the criteria in sequential organ function assessment

A

Respiratory rate >30

Confused

Low BP unresponsive to fluid challenge

= evidence of organ dysfunction

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99
Q

List viral causes of traveller’s diarrhoea

A

Norovirus

Rotavirus

Enteric adenovirus

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100
Q

Describe the reservoir of and illness caused by E. Coli 0157

A

Ruminants (beef)

Bloody diarrhoea, colic, low grade fever

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101
Q

What are the main points from history/examination which would suggest HIV infection in a patient with acute diarrhoea?

A

Diarrhoea is a common manifections of HIV infection - results from infection of enterocytes with HIV

Will often be accompanied by weight loss and other HIV indicator illnesses e.g. previous shingles, oral thrush, thrombocytopaenia

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102
Q

Describe the clinical features of typhoid/paratyphoid fever

A
  • Incubation period 5-21 days
    • Shorter in older, those with reduced gastric acidity, immunocompromised and where there is a high infectious load
  • Spectrum of clinical effect
    • Fever, myalgia, headache, cough, abdominal pain, constipation, diarrhoea –> septic shock, death
  • Mortality rates <1% with antibiotics (15% pre-antibiotic era)
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103
Q

Compare resistance against clarithromycin in typical and atypical pathogens

A
  • Resistance among typical pathogens relatively common - can only be used in non-severe infections
  • Resistance among ‘atypical’ pathogens relatively rare - is included in severe infections to cover these organisms (esp. severe community acquired pneumonia)
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104
Q

What is the role of the laboratory in antimicrobial stewardship programmes?

A
  • Optimisation of lab diagnosis - sampling, testing and minimisation of ‘over diagnosis’
  • Restricted reporting of organisms to prevent over treatment
  • Restrict reporting sensitivities to reduce use of innapropriate agents
  • Co-ordination of clinical advice with guidance
  • Data on resistance and CDI
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105
Q

Give examples of gram positive rods

A
  1. Clostridia (C difficile, C tetani)
  2. Bacillus (B anthracis, B cereus)
  3. Listeria (L monocytogenes)
  4. Others - corynbacteria (C diphtheriae) and propionobacterium (P acnes)
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106
Q

Why do some countries have higher antibiotic use than others?

A

In most countries, antibiotics can be easily purchased without prescription or involvement of a health profession or veterinarian

Poor quality medical and veterinary products are widespread, and often contain low concentration of active ingredients, encouraging emergence of resistant microbes

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107
Q

Other than AMR, what harm is caused by antibiotic overuse?

A
  1. Increase in broad spectrum antibiotics (cephalosporins) correlates with rise in CDI
  2. Avoidable toxicity - 1 in 5 hospital patients suffer >1 antibiotic associated adverse event altering their clinical path
  • Vascular device complications (including >50% of SABs)
  • Prolonged hospitalisation
  1. Opportunity cost - IV antibiotics divert nursing time from patient care
  2. Unnecessary prolonged Rx - wasteful and expensive
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108
Q

Describe the use of flucloxacillin

A
  • Synthetic penicillin developed to be resistant to beta-lactamase produced by staphlycocci
  • Antibiotic highly active against
    • Staphylococcus aureus (not MRSA)
    • Streptococci
  • No activity at all against gram negative organisms
  • Can be given orally but nausea limits dose
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109
Q

List four important clinical signs/symptoms associated with acute septic arthritis

A

Joint pain

Joint swelling

Warmth

Restricted movement

Seen in approx. 80% patients with septic arthritis

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110
Q

Describe types of Neisseria bacteria

A
  • N. meningitidis - causes bacterial meningitis and septicaemia
  • N. gonorrhoeae - causes gonorrhoea
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111
Q

In which environments is legionella pneumophila often transmitted?

A
  • Free living organism
  • Infects amoebae, found in things that aerosolise water
    • Jacuzzis
    • Hotel showers
    • Air conditioning
    • Hospitals
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112
Q

Describe the types of necrotising fasciitis and the causative organisms

A

4 classes of necrotising fasciitis

  • Type 1 - synergistic infection with anaerobes (e.g. bacteroides, peptostreptococcus) and aerobes (streptococci, enterobacteriaciae), more common in elderly diabetic patients - very broad antibiotic cover required
  • Type 2 - infection with group A streptococci (S pyrogenes or occasionally S aureus), mediated by toxin production
  • Type 3 - vibrio vulnificus, after trauma in sea water
  • Type 4 - fungal
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113
Q

Describe the structure and mechanism of action of beta-lactams

A
  • All beta-lactams have same structural feature - beta lactam motif, analogue of branching structure of peptidoglycan
  • Present analogue of peptidoglycan to enzymes which cause peptidoglycan crosslinking needed for bacterial cell wall
  • Inhibits crosslinking of cell wall peptidoglycan
  • Causes lysis of bacteria - bacteriocidal
  • Very fast acting
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114
Q

How does bacterial gastroenteritis usually differ in onset from food poisoning caused by ingestion of toxins or viruses?

A

Food poisoning caused by ingestion of toxins or viruses tend to have an abrupt onset of symptoms within hours of ingestion

Bacterial gastroenteritis tends to take longer to develop although can occur abruptly if a high amount of bacteria are ingested

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115
Q

How can potential hosts be protected from infection?

A

Vaccination

Prophylaxis

Nutrition

Treatment of immuno-suppressive

Protective isolation

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116
Q

Describe the mechanism of action of bactericidal antibiotics

A
  • Achieve sterilisation of the infected site by directly killing bacteria
  • Lysis of bacteria can lead to release of toxins and inflammatory material
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117
Q

What is the main issue with vancomycin in clinical use?

A

Under-dosing - cleared too fast in those with normal kidney function

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118
Q

List the examples of viral haemorrhagic fever

A
  • Lassa - most common, spread by rats found in grain barns in rural West Africa
  • Ebola/Marburg - probably same virus, spread by giant fruit bats
    • Now have drugs to treat
  • Congo-Crimean haemorrhagic fever - spread by tics
  • South American haemorrhagic fevers - rare
  • Rift valley fever
  • Dengue haemorrhagic fever - mosquitoes
  • Yellow fever
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119
Q

How should a catheter associated UTI be treated?

A
  • Remove catheter
  • Rx if symptoms/sepsis
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120
Q

Describe the lifecycle of the malarial parasite

A
  1. Sexual cycle completed within the gut of a female anopheles mosquito
  2. Sporozoites to saliva of mosquito
  3. Mosquito bites, parasite detects body heat and is released in the mosquitoes salvia, also contains a local anaesthetic to allow feeding without host awareness - sporozoites inoculated into human host
  4. Preerythrotic stage in liver - schizonts
  5. Schizonts rupture and parasite is liberated from the liver into the bloodstream
  6. Incorporated into RBC, matures
  • Immature trophozoite (ring stage)
  • Mature trophozoite
  • Schizont
  • Ruptured schizont - spread

Or become gametocytes –> infect other mosquitoes

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121
Q

Describe the mechanism of action of metronidazole

A
  • Enters by passive diffusion and produces free radicals
  • Effective against most anaerobic bacteria - not actinomyces
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122
Q

List the common antibiotic combination therapies

A

Amoxicillin + clavulanic acid = Augmentin

Piperacillin + taxobactam = Tazocin

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123
Q

How does human behaviour impact antibiotic prescription? How should this be challenged?

A
  • GPs feel under pressure to prescribe antibiotics - will prescribe when unsure if bacterial or viral infection, when they don’t deem it medically necessary or just to appease patients
  • Misconceptions - withholding antibiotics is always harmful or ‘wrong’
  • Expectations and experience drive antibiotic seeking behaviour - doctors can reinforce behaviour by prescribing antibiotics when not necessary
  • Evidence evolves - behaviour needs to also, keep up to date
  • Prescribing is multifaceted - hierarchy is bad, value all the team
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124
Q

What signs would strongly suggest a bacterial infection, prompting the prescription of an antibiotic?

A
  • Symptoms/signs of infection
    • Fever, sweats, rigors, shivers and shakes
  • Localising symptoms/signs
    • Dysuria and frequency
    • Dyspnoea, cough + green/brown sputum, crepitiations
    • Erythema, heat, swelling
    • Sore throat with exudate and adenopathy
  • Record indication for antibiotic
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125
Q

How is vancomycin administered?

A
  • Not absorbed from GI tract so almost always given IV
  • Oral route only used for treatment of C. diff
  • Long half-life so loading doses usually given
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126
Q

How is mycoplasma pneumoniae diagnosed?

A

Difficult to culture - not done

Serology

PCR (sputum/throat swab/viral gargle)

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127
Q

Describe the action of clindamycin

A
  • Similar in many was to macrolides
    • Same mechanism of action
    • Excellent oral absorption
    • Principle action against gram +ves
  • Some key differences
    • No action against aerobic gram -ves or atypicals
    • Excellent activity against anaerobes
  • Highly effective at stopping exotoxin production
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128
Q

How is an antimicrobial stewardship leadership team organised?

A
  • Leadership - dedicated team with expertise in infection management, prescribing surveillance and quality improvement
    • Infection specialists, clinical pharmacist
    • Multi-disciplinary clinical network and committee
    • Management engagement and IPC coordination
    • Clinical governance and patient safety
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129
Q

Give examples of barriers to and qualities which promote antimicrobial stewardship

A

Knowledge

Experience

Prescribing culture

Hierarchy

Team work/perception of roles and responsibilities

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130
Q

What pattern can be seen in antibiotic deployment and observation of antibiotic resistance?

A

Every time a new antibiotic is discovered resistance develops

Fewer antibiotics being discovered so resistance becomes a problem

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131
Q

Describe the reservoir of and illness caused by giardiasis

A

Contaminated food and water

Loose stool often associated with bloating and excess wind

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132
Q

Which disease-causing organisms are included in the clostridium species?

A

Causative agents of botulism and tetanus e.g. C. difficile

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133
Q

How can the heart and appendages be easily viewed in the diagnosis of endocarditis?

A
  • Heart and appendages easily viewed by an echo
    • Transthoracic echo is a non-invasive procedure that define both the structure and the function of the heart, not as sensitive as transoesophageal echo, which is more invasive (patients need to be sedated)
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134
Q

Define antibiotic spectrum

A
  • Range of bacterial species treated effectively by the antibiotic
  • Can vary widely even within the same antibiotic class e.g. Penicillins have no overlap in spectrum
  • Important to distinguish between lack of activity and resistance
    • Lack of activity - intrinsically the antibiotic won’t have any effect due to the nature of the bacterium
    • Resistance - bacterium has acquired an often genetic factor which prevents the antibiotic having an effect
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135
Q

What is the advantage of cephalosporins over penicillins?

A

Less susceptible to beta-lactamases

Good activity against gram -ves and gram +ves

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136
Q

Describe the appearance of staphylococci bacteria

A

Gram positive coccus, grow in irregular grape-like clusters

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137
Q

What are the most common causes of gastroenteritis in patients with no past medical history, no regular medication and no travel history?

A

Campylobacter sp.

Salmonella sp.

E. Coli 0157

Norovirus

Rotavirus

Giardiasis

Enterohaemorrhagic E. Coli

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138
Q

Give examples of gram negative rods

A
  1. E coli
  2. Klebsiella (K pneumoniae)
  3. Pseudomonas (P aeuroginosa)
  4. Others - proteus, serratia, salmonella, shigella etc.
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139
Q

When is doxycycline commonly used?

A

Soft tissue infections, respiratory tract infections (if allergic to amoxicillin)

Travel associated atypicals, anti-malarials

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140
Q

Give an example of how conjugation gives a bacterium resistance

A

Example of Conjugation and Beta Lactamases:

  • AMR mechanism = antibiotic degradation
  • Beta-lactamases in Enterobacteriaceae
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141
Q

List the causes of conjugated hyperbilirubinaemia

A
  • Biliary obstruction (extrahepatic cholestasis)
    • Both conjugated and unconjugated bilirubin accumulate in serum
  • Intrahepatic cholestasis
  • Hepatocellular injury
142
Q

Where are clostridium bacteria usually found?

A

Lower reproductive tract of women

143
Q

What would the immediate management plan for necrotising fasciitis be?

A
  • Immediate action must be taken
  • Patient requires an urgent surgical/plastics/orthopaedics review for wide debridement of all the infected tissue
  • Tissue from theatre should be sent to microbiology urgently for gram stain and culture
  • IV antibiotics important at this stage, unlikely to work whilst the necrotic tissue is present - avascular and full of organisms
    • Very broad cover needed, common combination is IV flucloxacillin (for gram -ves), IV benzylpenicillin (for streptococci), IV gentamicin (for gram negatives), IV metronidazole (for anaerobes) and PO/IV clindamycin (for anaerobes/reduction in toxin production)
    • If he was penicillin allergic/MRSA positive, vancomycin should be used
  • Discuss with microbiology or ID for advice
  • Hypotensive - require IV fluids rapidly, and catheterisation for monitoring of urine output
  • Should contact ITU, will have to go there post-op, and the anaesthetist will be able to give advice (may require inotropic support and a central line for access and monitoring CVP)
  • IV immunoglobulin could be considered, but there is a risk of anaphylaxis and the evidence base is lacking
144
Q

Describe the appearance of clostridium bacteria

A

Obligate anaerobes producing endospores, rod shaped

145
Q

Describe antibiotic treatment in biliary sepsis

A
  • Enteric flora - particularly gram -ve bacilli such as E.coli, Klebsiella spp. and enterobacter spp., gram positive bacteria such as enterococci and anaerobes such as bacteroides and clostridia
  • Appropriate empiric combinations may include:
    • Gentamicin, amoxicillin and metronidazole (issues with aminoglycosides and renal toxicity esp. in elderly)
    • Gentamicin and co-amoxiclav (issues w/ C diff and co-amoxiclav)
    • Piperacillin-tazobactam and gentamicin (broader gram -ve cover, covers anaerobes and most enterococci)
    • Ceftriaxone/cefotaxime and metronidazole (C. diff, lack of enterococcal cover)
    • Carbapenem (meropenem/imipenem) where history of infections with more resistant organisms e.g. ESBL producing coliforms - especially in those with recurrent biliary sepsis, prior biliary tract surgical procedures and with biliary-intestinal anastomoses
  • Treatment should not only be ‘supportive’ with appropriate antimicrobial therapy but must include investigation to identify possible obstruction of the biliary tree with subsequent decompression/drainage if required
146
Q

What is antimicrobial resistance?

A

Antimicrobial resistance occurs when microorganisms such as bacteria, viruses, fungi and parasites change in ways that render the medications used to cure the infections they cause ineffective

Global problem - treatment options limited, global consumption up, overuse and misuse leads to harm

147
Q

What are the features of empirical antibiotic guidelines?

A
  • Appropriate for target population
    • Primary vs secondary care, specialist vs generalist
    • National vs local adaptation
  • Key components
    • Decision support - when to avoid/use antibiotics (and how)
    • Appropriate investigations to support management
    • Takes into account epidemiology of infection including AMR
    • Population and individual risk of C. diff
    • Availability/cost
  • Specifics of antimicrobial prescribing
    • Choice, dose, route of admin, duration, severity assess, TDM
148
Q

Describe the reservoir of and illness caused by enterohaemorrhagic E. Coli

A

Contaminated food and water

Loose stool, nausea and colic in travellers (traveller’s diarrhoea)

149
Q

Describe the reservoir of and illness caused by campylobacter sp.

A

Poultry

Loose stool and nausea, colic, sometimes bloody stool

150
Q

How prevalent are healthcare acquired infections?

A

7-10% of every 100 hospitalised patients, 7 in high-income and 10 in low and middle-income countries, will acquire at least one healthcare-associated infection. 1/4 of these will be antibiotic resistant.

151
Q

What causes re-emergence of old diseases/appearance of new diseases/antibiotic resistance?

A

Multifactoral:

  • New patterns of travel (air) and trade (especially food)
  • Developments in agricultural practices/animal husbandry
  • Sexual behaviour
  • Medical interventions/developments in medical technology
  • Increases populations at extremes of age
  • Over/unnecessary use of antibiotics
  • The breakdown of economic, social and political systems
152
Q

How is Dengue fever transmitted?

A

Aedes mosquito - most common mosquito borne virus

153
Q

Describe the action of gentamicin

A
  • Reversibly binds to 30S ribosome
    • Bacteriostatic action
    • Results in prolonged post-antibiotic effect
  • Poorly understoof action on the cell membrane
    • Bactericidal action
    • Prominent at high concentrations
    • Results in rapid killing early in dosing interval
154
Q

How long should antibiotics be prescribed for in community/hospital acquired pneumonia (mild-severe)

A

5 days

155
Q

How is legionella pneumophila treated?

A
  • Intracellular - can’t use beta lactams (penicillins/cephalosporins)
  • Macrolides (clarithromycin)
  • Quinolones (ciprofloxacin)
  • Tetracyclines (doxycyline)
156
Q

What surgical prophylaxis should be given to an MRSA colonised patient in an emergency situation?

A

A glycopeptide e.g. vancomycin or teicoplanin

157
Q

Describe the methods of antibiotic therapy

A
  • Guided therapy - depends on identifying cause of infection and selecting agent based on sensitivity testing
  • Empirical therapy - best (educated) guess therapy based on clinical/epidemiology acumen, used when therapy cannot wait for culture (or if it is not practical to take a culture)
  • Prophylactic therapy - preventing infection before it begins
158
Q

How should traveller’s diarrhoea be managed?

A
  • Fluid replacement
  • Antibiotics (reduce duration by 24hrs) - not usually indicated, in developing countires spreading antibiotic resistance through antibiotic waste into open sewage systems
    • Quinolones
    • Azithromycin
  • Antimotility agents - caution
    • Diarrhoea is a physiologyical mechanism to get the organism out of the gut, antimotility agents reduce this
    • Can be used for symptomatic relief if needed
  • Investigations for other causes if long duration
159
Q

What initial radiology investigations should be performed in all patients with suspected acute cholangitis/biliary sepsis?

A
  • Transabdominal ultrasound or abdominal CT scan, to look for common bile duct dilatation/stones
  • USS has a high specificity for detection of stones but lower sensitivity for detecting bile duct dilatation
  • CT has high sensitivity in detection of bile duct dilatation and can identify biliary stenosis but has a lower sensitivity for bile duct stones
160
Q

How is malaria treated?

A
  • Artemether compounds e.g. Riamet
  • Quinine and Doxycycline
    • Quinine has bad side effects - nausea, headache
161
Q

Describe the appearance of enterococci bacteria

A

Gram positive coccus, often occur in pairs or short chains

162
Q

Which bacteria are sensitive/resistant to ciprofloxacin?

A

Highly sensitive - E. coli and other coliforms, neisseria, haemophilus, pseudomonas

Sensitive - staphylococcus, streptococcus

Resistant - enterococcus, clostridium, bacteroides

Atypicals also sensitive - legionella, mycoplasma, coxiella, chlamydia, chlamydophia

163
Q

Describe the toxicity of metronidazole

A
  • Causes unpleasant reaction with alcohol
    • Antabuse - inhibits alcohol metabolic pathway, acetaldehyde builds up
  • Peripheral neuropathy with long term use
164
Q

Give examples of second line agents for short course tuberculosis therapy

A

Quinolones and aminoglycosides

165
Q

Define resistance

A
  • Defined from a biological perspective - national variations in breakpoints
    • Resistance definitions usually based on in-vitro quantitative testing bacterial suspensions to antibacterial agents
    • Based on minimum inhibitory concentration
    • Breakpoint - concentration of antibiotic which defines whether a species is sensitive or resistant
  • Defined from a clinical perspective
    • Clinical resistance - when infection is highly unlikely to respond even to maximum doses of antibiotics (EUCAST)
166
Q

Describe the action of quinolones

A
  • Broad spectrum, bactericidal antibiotics
  • Ciprofloxacin - good against gram -ves, weaker against gram +ves, commonly used in UTIs/abdominal infection
  • Levofloxacin - sacrifices some gram -ve activity for stronger gram +ve action - respiratory tract infections
  • Active against many ‘atypical’ pathogens including legionella
167
Q

How should an uncomplicated UTI (cystitis) be treated? Why?

A
  • 30% of cystitis is culture negative
  • Majority of infection is self-limiting
  • NSAIDs may be as effective as Abx in symptom control
  • Consider delayed Abx
  • If prescribing Abx - trimethoprim or nitrofurantoin
168
Q

List the beta-lactamases which effect beta-lactam antibiotics

A
  • Penicillins inactivated by penicillinase
  • Penicillinase resistant antibiotics inactivated by beta-lactamase
  • Cephalosporins inactivated by extended spectrum beta-lactamase - secreted by enterobacteriaceae
    • Generations of cephalosporins designed to be resistant to beta-lactamases
169
Q

Compared the structure of gram negative and gram positive bacteria

A
  • Gram positive
    • Cell membrane
    • Peptidoglycan cell wall - very thick, more structured
  • Gram negative
    • Cell membrane
    • Peptidoglycan cell wall - thin
    • Outer membrane
    • Periplasm
170
Q

Describe the features of Dengue haemorrhagic fever

A
  • <1% infections
    • Spectrum of illness, breakbone –> haemorrhagic
  • Definition
    • Increased vascular permeability
    • Thrombocytopaenia
    • Fever
    • Bleeding
      • Bleeding through mucous membranes - haemoptysis, haematemesis
  • Less likely in travellers
  • People infected with multiple types of Dengue fever one after the other - immune system can’t cope –> Dengue haemorrhagic fever
171
Q

How should pneumonia be managed?

A

A - Airway (conscious level?)

B - Breathing (oxygen, ITU)

C - Circulation (shock? - fluids?)

Antibiotics - IV or Oral? Admission to hospital?

  • CURB65 - mortality increases with score 2+
  • Sepsis - qSOFA score
  • Hypoxia?
172
Q

Give an example of how transformation gives a bacterium resistance

A

Example of transformation and penicillin R:

  • AMR mechanism = target modification
  • Example - change penicillin binding proteins, leads to penicillin resistance in pneumococci
  • Penicillin binding proteins are part of peptidoglycan bridge - target for antibiotics
  • Bacteria change shape of penicillin binding proteins - beta-lactams can’t bind, resistance develops
173
Q

How is aztreonam administered?

A

Only given IV - no oral absorption

174
Q

What measures can be used when not prescribing an antibiotic?

A
  • Mainly applicable in primary care
  • Reassurance/explanation
    • Printed information
  • Symptomatic measures: fluids, analgesia
  • Delay script
  • Review date/opportunity - ‘safety netting’
175
Q

How are quinolones administered?

A

Excellent oral bioavailability - can use oral dosing even in severe infection

176
Q

How is typhoid/paratyphoid fever diagnosed?

A
  • Travel history
    • Area visited
    • Food and drink
    • Pre-travel vaccination/advice
      • Vaccine only 75% effective
  • Blood culture
    • 60-80% positive
    • Don’t wait till they have a fever
  • Stool culture
    • 30% positive
  • Serology
    • Poor sensitivity/specificity - don’t use
177
Q

What are the benefits of antimicrobial stewardship in Scotland?

A

Associated with:

  • Reduction in broad spectrum antibiotics
  • Reduction in total antibiotics use in primary care
  • Reduction in C. diff
  • Reduction in MRSA
  • Reduction in GNB mortality
  • Reduction in AMR in gram negative bacteraemia
178
Q

When should IVOST be considered?

A

Clinical improvement + oral route available + uncomplicated infection –> IVOST

179
Q

Describe the management of a patient with acute gastroenteritis

A
  1. Rehydration
  • Most important aspect of management
  • Most complications result from dehydration
  • Depending on clinical condition and ability to take oral fluids may need to be done using IV fluids
  1. Antibiotics
  • Not indicated in bacterial causes of gastroenteritis
  • Patients with significant co-morbidity or prolonged symptoms - can shorten duration of diarrhoea
  • Usually use quinolones (e.g. ciprofloxacin), needs to be justified because of the risk of C. diff infection
  1. Infection control
  • Most causes transmissible from person to person, important that patients are instructed to be careful about hand washing
  • Identify if patient is food handler as restrictions may apply to when they can safely return to this
180
Q

What needs to be considered when a patient with acute gastroenteritis begins to improve clinically?

A
  • Decisions regarding discharge depend on clinical condition
  • Patient should be advised regarding good hand hygiene to prevent spread to other persons within the house
  • Antibiotics still not routinely recommended and may prolong carriage of the organism
  • Public health will be notified by the laboratory of the positive result and an environmental health officer will contact the patient to discuss risk factors for the infection
  • Should not return to work if handling food until symptom free for 48hrs
181
Q

How do bacteria acquire resistance genes?

A
  • Intrinsic resistance
    • Normally chromosome encoded - part natural makeup of bacteria
    • Resistance gene in plasmid - easily transferrable
  • Extrinsic resistance - transduction, transformation, conjugation
    • Transduction = DNA packaged in a bacteriophage infects the recipient bacterium and becomes incorporated into the recipient DNA
    • Transformation = transfer of genetic material takes place from donor to recipient bacterium through the liquid medium, bacterium takes up extracellular donor DNA
    • Conjugation - transfer of genetic material from one cell to another through direct contact or bridge-like connect
182
Q

Describe the types of mosquitoes and diseases they carry

A
  • Aedes mosquito
    • Yellow fever, Dengue fever
    • Have their bum on the ground when feeding
    • Day biter, will also occasionally bite in the evening
  • Anopheline mosquito
    • Malaria
    • Have their bum in the air when feeding
    • Tend to feed nocturnally
  • Lay eggs in water, mosquito borne illnesses higher risk around water
183
Q

What are the systemic complications associated with infective endocarditis?

A
  • Septic emboli - infarction of kidneys, spleen and other organs, pulmonary emboli in patients with concomitant right-sided endocarditis
  • Cardiac complications (up to 50%) - valvular insufficiency, heart failure
  • Neurological complications (up to 40%) - embolic stroke, intracerebral haemorrhage, brain abscess
  • Metastatic infection - osteomyelitis, septic arthritis, splenic or psoas abscess
  • Systemic immune reaction e.g. glomerulonephritis
184
Q

Describe the major criteria of the Duke criteria

A
  • Positive blood cultures
    • Typical microorganisms consistent with IE from two separate blood cultures (staph aureus, strep viridans, staph gallolyticus, HACEK, enterococci) taken >12 hours apart
      • HACEK - haemophilus, aggregatibacter, cardiobacterium, eikenella, kingella
    • Persistently positive blood cultures - if from organisms which are more commonly skin contaminants, 3 or a majority of >4 separate blood cultures (with first and last drawn at least one hour apart)
    • Single positive blood cultures for coxiella burnetii or phase I IgG antibody titer >1:800
  • Evidence of endocardial involvement
    • Echocardiography positive for IE, vegetation (oscillating intracardiac mass on a valve or on supporting structures, in the path of regurgitant jets or on implanted material, in the absence of an alternative anatomic explanation)
    • Abscess
    • New partial dehiscence of prosthetic valve
    • New valvular regurfiation (increase or change in prexisting murmur is not sufficient)
185
Q

Describe charcot’s triad

A

Describes the clinical presentation of acute cholecystitis:

  • Fever
  • Abdominal pain
  • Jaundice

Approximately only 50-70% of patients have all three findings

186
Q

Define antimicrobial/antibiotic stewardship

A
  • Systemic approach to safe and effective use of antibiotics - optimising outcome, minimising harm and preserving future therapies = taking care of antibiotics
  • Antimicrobial stewardship achieved through
    • Monitoring/surveillance
    • Guidelines/protocols
    • Specific restrictions (reporting/Abx)
    • Specific interventions
    • Multidisciplinary working
187
Q

What is the most common bacterial cause of septic arthritis in an adult?

A
  • Staphylococcus aureus most common
  • Less common - streptococci (strep. Pneumoniae)
  • Septic arthritis due to gram negative bacilli typically occurs in older adults, in patients with underlying immunosuppression, or intravenous drug users, or as complication of trauma
188
Q

List the most common bacteria isolated in acute cholecystitis/biliary sepsis

A
  • Gram negative organisms
    • E coli (50%)
    • Klebsiella species (20%)
    • Enterobacter species (10%)
  • Gram positive organisms
    • Enterococcus (approx. 10-20%)
  • Anaerobes, such as bacteroides and clostridia species are typically presented and involved in polymicrobial infection, but their frequency is likely to be underestimated by standard culture techniques
189
Q

What criteria is used to diagnose infective endocarditis?

A

Modified Duke criteria

190
Q

Where are Neisseria usually found?

A

Colonies mucosal surfaces

191
Q

What is the main issue with the antibiotics used in tuberculosis therapy?

A

Hepatoxicity - rare but can be serious

192
Q

List the important predisposing risk factors for infective endocarditis

A
  • Age >60 years
    • More likely to develop degenerative valve disease and require valve replacement, both are associated with increased risk of IE
  • Male
  • Intravenous drug use
    • Risk associated with bloodstream seeding with skin flora, oral flora and/or organisms contaminating the drug or materials used for injection
    • Some illicit drugs may induce valvular endothelial damage, predisposing to infection
  • Poor dentition or dental infection/procedures
  • Structural heart disease/valvular heart disease/congenital heart disease
193
Q

What is the major adverse effect of clindamycin?

A
  • Excellent activity against anaerobes means clindamycin particularly effective at disrupting colonic flora
  • Became notorious for causing C. difficile - now understood that all antibiotics can cause CDI
194
Q

Describe the action of macrolides

A

Good spectrum against gram +ves and respiratory gram -ves

Also active against atypicals - legionella, mycoplasma, chlamydia etc.

195
Q

List the possible portals of entry of infections

A
  • Respiratory tract
  • Mucous membranes
  • Skin - non-intact
  • Mouth (faecal-oral route)
196
Q

Who needs to be informed if a patient dies as a result of C. diff infection?

A
  • The procurator fiscal should be informed as the patient has died as a direct result of a Hospital Acquired Infection (HAI)
  • It is good practice to inform the patient’s GP that the patient has died
  • The infection control team should also be made aware that the patient has died as a result of CDI - may already know
  • If the patient has been severely mismanaged and has died as a direct consequence of an avoidable HAI, the medical director should be informed as there may be issues regarding the competence of the doctors who were looking after the patient which need urgently addressed
197
Q

Describe the standard short course therapy for tuberculosis

A
  • Isoniazid
    • Bactericidal to fast growing mycobacteria
    • Causes hepatotoxicity, peripheral neuropathy, B3 deficiency prevented with pyridoxine
  • Rifampicin
    • Bactericidal against slowly replicating organisms in necrotic foci
    • Liver, bone marrow and renal toxicity - relatively uncommon
  • Pyrazinamide
    • Bactericidal, even against slow growing mycobacteria intracellularly
    • Principle toxicity is hepatic, also causes arthralgia
  • Ethambutol
    • Bacteriostatic against slow growing mycobacteria
    • Principle toxicity is optic neuritis, watch for loss of colour vision
198
Q

How is the Duke criteria used to diagnose infective endocarditis?

A

Diagnosis of infective endocarditis:

  • 2 major criteria
  • 1 major and 3 minor
  • 5 minor

Possible IE - 1 major + 1 minor or 3 minor

199
Q

In a patient showing signs of severe sepsis, what are the top priorities for immediate treatment?

A
  • Must establish IV access, commence fluid resuscitation and start appropriate antibiotics all within the next hour
  • Other investigations such as routine blood tests, blood cultures and a joint aspirate are very important in diagnosis
  • Need to resuscitate patient and initiate effective antibiotic treatment
  • High risk of dying if delay and septic shock is a medical emergency
200
Q

How does the structure of gram positive/negative bacteria affect their susceptibility to antibiotics?

A
  • Gram positive - thick peptidoglycan wall
    • Can protect self from outside hazards
    • Can’t control what comes into contact with cell wall
  • Gram negative - thin peptidoglycan wall, outer membrane and periplasm
    • More control over what accesses the cell wall - better at developing resistance mechanisms
201
Q

List the strategies to prevent healthcare associated infection

A

Isolation

Screening

Cohorting

Standard and transmission based precautions

Surveillance

Antimicrobial stewardship

202
Q

What clinical history suggests necrotising fasciitis?

A

Disproportionate pain initially

NSAID use

Mild preceding trauma

SIRS/sepsis

Rapid progress over several hours

Dusky discolouration

203
Q

Why is flucloxacillin not an appropriate empirical agent in suspected MRSA infection?

A

Flucloxacillin has no activity against MRSA

204
Q

What does the evidence suggest about the ideal length of an antibiotic course?

A

Shorter antibiotic course better, once clinically better from acute bacterial infection don’t need to finish long course, shorter therapy associated with less harm

205
Q

Describe the drug interactions of rifampicin

A
  • Potent CYP450 enzyme inducer
  • Most drugs that undergo hepatic metabolism affected
  • Important to look up interactions when starting
206
Q

Describe the clinical presentation of legionella pneumophila

A

Atypical

Non-specific - fever, malaise, myalgia

Consolidation on examination/imaging

207
Q

What antibiotics should generally be used for non-severe infections (community or hospital)?

A
  • Use narrow spectrum agents
  • Lower respiratory tract - amoxicillin or doxycycline
  • Lower UTI - trimethoprim or nitrofurantoin
  • Mild cellulitis - flucloxacillin or doxycycline
208
Q

How is Dengue fever managed?

A

Symptomatic management only

209
Q

List the steps in antibiotic prescribing

A

Is an antibiotic required?

If yes -

Which antibiotic?

Administer IV or oral?

Dose/interval (check renal function)

Adjunctive measures? E.g. surgery for source control

Duration and IVOST (IV-oral antibiotic switch therapy)?

Review

Is an antibiotic required?

210
Q

How can type 1 and type 4 penicillin hypersensitivity be distinguished?

A

Immediate (<1 hour) = type 1

Delayed (blistering rash and systemic illness) - type IV

211
Q

Describe cross reactivity between antibiotics in beta-lactam allergies

A
  • Patients allergic to a penicillin will usually be allergic to other penicillins
  • Cross reactivity with other antibiotic classes is much lower
    • Some patients with penicillin allergy may be safely managed with other beta-lactams
    • Particularly important if patient presents with life-threatening infection (esp. meningitis)
212
Q

Why is the development of new antibiotics so challenging?

A
  • New antibiotics need to combat resistance
  • New antibiotics are reserved to guard against resistance
  • It can take in excess of 10 years from discovery to launch, estimated cost $1 billion to bring a new drug to market
  • Therefore:
    • Company develops a new agent
    • Use is restricted - antibiotic ‘put on shelf’
    • Company gains minimal income and discontinues antibiotic discovery and development
    • Fewer new antibiotics developed
    • Problem worsens
213
Q

What antibiotic therapy is appropriate for treating intra-abdominal sepsis?

A

Combination of amoxicillin, gentamicin and metronidazole

214
Q

What are the common clinical signs and symptoms of infective endocarditis?

A
  • Fever in up to 90%, associated with chills, anorexia and weight loss
  • Malaise, myalgias, arthralgias, night sweats
  • Dyspnoea
  • Cardiac murmurs (in approx. 85%)
  • Splenomegaly
  • Cutaneous manifestations - petechiae
  • Splinter haemorrhages

Relatively uncommon clinical manifestations highly suggestive of IE include:

  • Janeway lesions - nontender erythematous macules on the palms and soles of feet
  • Osler nodes - tender subcutaneous nodules on pads of fingers and toes, thenar and hypothenar eminences
  • Roth spots - exudative, oedematous haemorrhagic retinal lesions
215
Q

Which bacteria are sensitive/resistant to gentamicin?

A

Highly sensitive - E. coli and other coliforms, pseudomonas

Sensitive - staphylococcus

Minimally sensitive - streptococcus, haemophilus, neisseria

Resistant - enterococcus, clostridium, bacteroides

216
Q

Describe the reservoir of and illness caused by Norovirus

A

Person to person, nosocomial (hospital acquired)

Nausea and vomiting with loose stool

217
Q

List infectious diseases which cause significant mortality globally

A
  • Lower respiratory infections
  • HIV
  • Diarrhoeal diseases
  • TB
  • Malaria
  • Measles
  • Hepatitis B
218
Q

List the signs and symptoms of Scarlet fever

A
  • Symptoms
    • Sore throat
    • Headache
    • Neck pain
    • Fever
  • Signs
    • Erythrodermic rash
    • Red back of throat
    • Strawberry tongue with prominent papillae
    • Tachycardic
    • Hypotensive
    • High respiratory rate
219
Q

When is clindamycin used?

A

Added to patients with gram +ve toxin mediated disease e.g. toxic shock syndrome, necrotising fascitis

Soft tissue infections - drug use/surgical wounds

220
Q

Where are enterococci usually found?

A

Usually present in the bowel and gut

221
Q

Define sepsis

A
  • Life-threatening organ dysfunction which occurs as a result of a dysregulated host response to an infection
    • Quantified by an increase in the sequential organ failure assessment (SOFA) score of >2 for the organ in question
    • Or quick SOFA = confusion or hypotension or tachypnoea
222
Q

In which infections is aztreonam the antibiotic of choice?

A

Used in gram -ve respiratory tract infections e.g. bronchiectasis caused by pseudomonas

223
Q

List the adverse effects of clarithromycin

A
  • Diarrhoea and vomiting
  • QT prolongation - sudden death
  • Hearing loss with long term use
224
Q

How should the antibiotics used to treat pneumonia be prescribed?

A
  • Use Empirical Antibiotic Therapy Guidelines
  • More severe - broader cover, macrolide and beta-lactam
  • If mild probably pneumococcal, better to use narrower spectrum
225
Q

How long should antibiotics be prescribed for bone-joint infection and what is this determined by?

A

>42 days, source control

226
Q

List the typical and atypical causative organisms of bacterial pneumonia

A

Typical -

  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Moraxella catharralis
    • Usually occurs in those with disturbed lung architecture e.g. COPD

Atypical -

  • Mycoplasma pneumoniae
  • Legionella pneumoniae
  • Chlamydophila pneumoniae
  • Chlamydophila psittaci
    • From parrots, very rare
227
Q

Give an example of how transduction gives a bacterium resistance

A
  • Tetracycline R and transduction
  • AMR mechanism = drug efflux
  • Phage gene transfer - genes for efflux pumps transferred to E. coli and salmonella, gives resistance against tetracycline R
228
Q

Describe the use of carbapenems

A
  • Ultra-broad spectrum beta-lactam antibiotics developed during search for beta-lactamase inhibitors
  • Excellent spectrum of activity against gram +ve and -ves
  • No activity against MRSA
  • Resistant to beta-lactamases
    • New beta-lactamases are emerging which lyse carbapenems
229
Q

List the possible mechanisms of action of antibiotic agents

A
  1. Bactericidal
  2. Bacteriostatic
230
Q

How do you determine the source of bacteraemia in positive blood culture results?

A
  • May get clues from history, findings on examination and type of organism isolated
  • May need further investigations
  • If treat with short-term antibiotics it may resolve temporarily, but then recur if the source has not been identified and treated
231
Q

List the indications for IV antibiotic therapy

A
  • Sepsis syndrome, SIRs or rapidly progressing infection
  • Special conditions
    • Infective endocarditis
    • CNS infection
    • Bacteraemia (S. aureus)
    • Osteomyelitis (initially)
  • Mod-severe skin and soft tissue infection
  • Infection and oral route compromised
  • No oral formulation of antibiotic available
232
Q

List the main classes of infection causing bacteria

A
  • Gram negative
    • E. coli
    • Other coliforms
    • Neisseria
    • Haemophilus
    • Pseudomonas
  • Gram positive
    • Streptococcus
    • Enterococcus
    • Staphylococcus
  • Anaerobes - gram positive and negative
    • Clostridium
    • Bacteroides
233
Q

Describe the toxicity and therapeutic problems associated with quinolones

A

Toxicity:

  • GI toxicity
  • QT prolongation
  • Tendonitis - high dose/prolonged therapy esp.
    • Worry about Achilles tendon rupture

Other therapeutic problems:

  • Resistance emerging on therapy/tendon damage
  • C. diff infection (esp. in North America)
234
Q

How long should antibiotics be prescribed for in infective endocarditis and what is this determined by?

A

>42 days, determined by complexity

235
Q

Which beta-lactams are safe in penicillin allergy?

A

Aztreonam (monobactam) has no cross reactivity to penicillin so can be given to those with penicillin allergy (except anaphylaxis)

236
Q

What are the main points from history/examination which would suggest diverticular disease in a patient with acute diarrhoea?

A

Often older patients with a history of alternating constipation and diarrhoea

Diverticulae can become impacted with faeces leading to localised infection, so called ‘diverticulitis’

237
Q

List the uses of antibiotics

A
  • Treat infections
  • Used in majority of surgical procedures
    • Implant surgery (orthopaedic, vascular etc.)
    • Cancer surgery
    • Cardiac, neurosurgery
  • Cancer chemotherapy
  • Immunotherapy
  • Organ transplant
238
Q

What investigations should be done in suspected pneumonia?

A
  • Blood tests
    • FBC
    • U&Es
    • ABGs/oxygen sats
  • Microbiology
    • Blood cultures
    • Sputum culture
    • Throat swab
    • Urine legionella antigen
  • Investigations
    • Chest X-ray
    • ECG
239
Q

List the aspects of bacteria that can be targetted by antibiotics

A
  1. Cell wall peptidoglycan (approx 50% of antibiotics)
  2. Metabolism - anti-metabolites interfere with metabolic processes in bacteria
  3. Ribosome - critical for bacteria protein production
  4. DNA - esp. replication and repair
240
Q

How are CREs transmitted?

A
  • Routes for patients
    • Direct contact through carriage of CRE on hands of HCWs
    • Indirectly via contaminated environmental surfaces or shared equipment
241
Q

List conditions that give rise to the carriage of resistant bacteria

A
  • Poor hygiene and sanitation
  • Overuse of antibiotics in livestock and fish farming
  • Over-prescription of antibiotics
  • Poor infection control in healthcare settings
  • Absence of new antibiotics being discovered
  • Antibiotic waste polluting rivers
242
Q

What three key investigations are recommended to diagnose septic arthritis?

A

Blood cultures

Imaging - X-ray, CT

Joint aspirate - for microscopy and culture

243
Q

Describe the epidemiology of bacterial pneumonia

A

5-11 per 1000 population

Highest in very young and elderly

22-42% patients admitted to hospital

Mortality of 8-14% (30% in ITU)

244
Q

How long should antibiotics be prescribed for in staph aureus bacteraemia and what is this determined by?

A

>14 days, determined by source control

245
Q

What are the main points from history/examination which would suggest bowel cancer in a patient with acute diarrhoea?

A

Often older persons with altered bowel habit

Weight loss may be prominent

246
Q

Which bacteria are sensitive/resistant to vancomycin?

A

Highly sensitive - staphylococcus, enterococcus, streptococcus, clostridium

Resistant - E. coli, other coliforms, neisseria, haemophilus, pseudomonas, bacteroides

247
Q

Give examples of highly prevalent minor infections which significantly impact healthcare in the UK

A
  • UTIs
  • Respiratory tract infections
  • Skin infections
  • Infectious intestinal disease
  • Healthcare associated infection e.g. MRSA/C. diff
248
Q

Describe the differences in generations of cephalosporins

A

1st, 2nd, 3rd, 4th and MRSA active

Gram negative spectrum increases with each generation, some loss of gram positive activity

Recent introduction of MRSA active cephalosporins

249
Q

List the causes of unconjugated hyperbilirubinaemia

A
  • Overproduction of bilirubinDyserythropoiesis e.g. Sickle cell disease
    • Incorporation of haemoglobin into erythrocytes is defective, leading to degradation of a large fraction of unincorporated haemoglobin
  • Reduced bilirubin uptake
  • Impaired bilirubin conjugation
250
Q

Where is E. Coli usually found?

A

Usually found in the lower intestine

251
Q

Which bacteria are sensitive/resistant to Levofloxacin?

A

Highly sensitive - streptococcus, staphylococcus

Sensitive - E. coli and other coliforms, neisseria, haemophilus, pseudomonas

Resistant - clostridium, bacteroides, enterococcus

Atypicals also sensitive - legionella, mycoplasma, coxiella, chlamydia, chlamydophia

252
Q

What should be included in a history taken from a returning traveller?

A
  • What pre-travel advise did you receive (if any)?
    • Vaccines
    • Prescribed medications - did they actually take them?
      • E.g. anti-malarials
  • Where did you go?
    • Country/countries visited
    • Urban/rural stay within countries
  • How did you travel?
    • Planes, boats, public transport etc.
  • How long did you travel for?
    • Longer stay more likely to be exposed to local pathogens
    • Some illnesses present soon after travel
  • What did you do?
    • Activities in water? - Schistosomiasis
  • Sexual history
  • Co-morbidities
    • Might have missed medication while travelling, chronic illnesses can de-stabilise
253
Q

Which antibiotics should be used in a rapidly progressing/immediately life-threatening infection where the source is unknown?

A
  • IV amoxicillin 2g 6hrly
      • IV gentamicin (max 3-4 days)
  • If S. aureus suspected add IV flucloxacillin 2g 6 hrly
  • If MRSA suspected or true penicillin/beta-lactam allergy - IV vancomycin + IV gentamicin
  • If severe streptococcal infection suspected add IV clindamycin 600mg 6 hrly
  • Duration - review with response/micro results at 72 hours
254
Q

What is the antibiotic of choice in a patient who is severely unwell with a UTI?

A
  • Amoxicillin and gentamicin
  • No issue of resistance with gentamicin and going into hospital anyway so can be administered IV
  • Amoxicillin - could be another infection rather than a UTI if very unwell and elderly
255
Q

Describe the potential adverse effects of beta-lactams

A
  • GI toxicity
    • Nausea and vomiting
    • Diarrhoea
    • Cholestasis
  • Infection
    • Candidiasis - oral, vulvovaginal
    • Clostridium difficile infection
    • Selection of resistant bacteria
  • Hypersensitivity
    • Type 1 - urticaria, anaphylaxis
    • Type 4 - mild to severe dermatology
    • Interstitial nephritis
  • Miscellaneous rare reactions
    • Seizure
    • Haemolysis
    • Leucopenia
256
Q

List the modes of transmission of infection

A
  • Direct
    • Direct contact
    • Droplet spread
  • Indirect
    • Airborne
    • Vehicle borne (food water fomites)
    • Vector borne (mechanical or biologic)
257
Q

What is the differential diagnosis of an erythematous swollen leg which is tender to touch, with systemic symptoms of infection?

A

Cellulitis

Necrotising fasciitis

Trauma - haematoma (systemic symptoms make this less likely)

Myositis

Osteomyelitis

DVT (unlikely in active young patient)

Abscess - IVDU?

Erythema nodosum - nodules, underlying autoimmune disease, TB, EBV etc.

258
Q

What are the main points from history/examination which would suggest sepsis in a patient with acute diarrhoea?

A

Results from shunting of blood away from splanchnic circulation

Be aware of the presence of SIRS criteria and look for other sources of infection (pneumonia, strep throat, meningitis, cellulitis)

259
Q

Why is tuberculosis difficult to treat? How is this overcome?

A
  • Slow growing, high bacterial burden, limited acess of drugs to granuloma (no vascular supply)
  • Solution - prolonged courses of therapy (usually 6 months), combination therapy to prevent resistance and kill growing/resting organisms
260
Q

What are the main points from history/examination which would suggest chronic pancreatitis in a patient with acute diarrhoea?

A

Often results from previous epidsodes of acute pancreatitis

Alcohol history important

261
Q

When are carbapenems used?

A

When worried about resistance - lots of antibiotic related harm

262
Q

Describe the mechanism of action of vancomycin

A

Inhibits cell wall formation in gram +ve only (no gram -ve action - too big to get through outer membrane)

Not dependent on penicillin binding proteins so effective against resistant organisms

Resistance in clinical isolates v rare

263
Q

How are bacteria broadly classified?

A

Gram negative or gram positive - different staining, structure and behaviour

264
Q

Describe the process by which AMR develops

A
  1. Patient acquires infection
  2. Antibiotics given to treat infection
  3. Infection causing organism wiped out, other organisms affected
  4. Resistant organisms emerge and overgrow
  5. Resistant organisms transferred via skin/stool to environment
265
Q

Give examples of new infectious diseases which have appeared in recent times

A

HIV, Ebola, Zika virus, Candida auris, Middle Eastern Respiratory Syndrome

266
Q

How long is the incubation period in Dengue fever?

A

Incubation 5-14 days

267
Q

Describe the clinical features of malaria

A
  • Clinical features
    • Fever, malaise, headache, myalgia, diarrhoea etc. (often flu-like symptoms)
    • Anaemia
    • Jaundice
    • Renal impairment
  • Severe malaria
    • Parasitaemia >2% (percentage of red cells with parasites)
    • Cerebral malaria
    • Severe anaemia
    • Renal failure
    • Shock
    • DIC
    • Acidosis
    • Pulmonary oedema
268
Q

What are the main points from history/examination which would suggest ischaemic bowel in a patient with acute diarrhoea?

A

Often older patients with a history of vascular disease or atrial fibrillation

Presents with diarrhoea, abdominal pain is prominent symptom

269
Q

Which bacteria are sensitive/resistant to clarithromycin?

A

Highly sensitive - streptococcus, staphylococcus

Senstivie - neisseria, haemophilus

Minimally sensitive - enterococcus

Resistant - clostridium, bacteroides, pseudomonas, E. coli and other coliforms

Atypicals also sensitive - legionella, mycoplasma, coxiella, chlamydia, chlamydophila

270
Q

List the regions defined by geosentinel surveillance

A

Central America

Caribbean

South America

Sub-Saharan Africa

Southeast Asia

South Central Asia

Other developing regions

271
Q

Where are staphylococci bacteria usually found?

A

Skin and mucous membranes

272
Q

How is guided antibiotic therapy used clinically?

A
  • Use antibiotic which has limited action to the bacteria causing infection (narrow spectrum)
  • If possible limit penetration to site of infection
  • Achieve clinical cure with as little impact on colonisation and resistance as possible
273
Q

Which drugs do macrolides interact with?

A
  • Clarithromycin - over 400 drug interactions
    • Cytochrome P450 inhibitor - causes drug interactions
  • Simvastatin - if prescribed with clarithromycin simvastatin levels exponentially rise
    • Avoid co-prescription
    • Temporarily stop simvastatin
  • Atorvastatin
  • Warfarin
274
Q

How is rifampicin usually used?

A
  • As part of combination therapy for Tuberculosis
  • In addition to another antibiotic in serious gram positive infection (esp. staph aureus)
275
Q

Describe the clinical presentation of viral haemorrhagic fever

A
  1. Exposure
  2. Up to 21 days later - non-specific febrile illness
  3. Haemorrhagic manifestions
  4. Sepsis syndrome/shock (secondary bacterial infection through loss of mucous membranes)
  5. Death
276
Q

How can antibiotic resistance be combatted without the use of new antibiotics?

A

Taking a multidrug approach by combining different antibiotic compounds with each other, or by using a combination of antibiotics with non-antibiotics

277
Q

Describe the mechanism of action of bacteriostatic antibiotics

A
  • Suppresses growth but doesn’t directly sterilise infected site
  • Requires additional factors to clear bacteria - immune mediated killing
    • Immune system can usually easily mop up the bacteria - only a problem in areas with little immune penetration (e.g. heart valves) or in very immunocompromised individuals
278
Q

How is mycoplasma pneumoniae treated?

A
  • No cell wall, can’t use beta lactams (penicillins/cephalosporins)
  • Have to use antibiotics which have different targets
    • Macrolides (clarithromycin) - ribosome
    • Tetracyclines (doxycycline) - ribosome
    • Quinolones (ciprofloxacin) - DNA
279
Q

What are ESBLs?

A
  • Extended spectrum beta lactamases - enzymes produced by enterobacteriaceae such as E. coli and Klebsiella (usually found in the gut) which makes them resistant to antibiotics e.g. Penicillins, Cephalosporins, Carbapenems, Fluoroquinolones and Aminoglycosides
  • Increasing incident of ESBLs globally
    • E.g. New Dehli metallo-beta-lactamase 1 (NDM-1) producing enterobacteriaceae
    • Spread from Asia to UK via air travel
280
Q

Which bacteria are sensitive/resistant to meropenem?

A

Highly sensitive - staphylococcus (not MRSA), E. coli, other coliforms, neisseria, haemophilus, pseudomonas, bacteroides, clostridium, streptococcus

Sensitive - enterococcus

281
Q

Describe the types of haemophilus influenzae

A
  1. Typeable - B (vaccinated against)
  2. Non-typeable
  • Colonisation of upper respiratory tract - can cause ENT infections, conjunctivitis, sinusitis, pneumonia
  • Abrupt onset
    • Cough
    • Fever
    • Pleuritic chest pain
  • Dull percussion
  • Coarse crepitations
  • Increased vocal resonance
282
Q

Describe the pathogenesis of infective endocarditis

A
  • Infective endocarditis = infection of the endocardial surface of the heart valves
    • Can involve previously normal valves, a valve damaged as a result of prior endocarditis, rheumatic heart disease or a degenerative process or a prosthetic valve
    • Fibrin and platelets attach to the surface of damaged heart valves producing a sterile thrombotic endocarditis
    • Certain bacteria can adhere to these lesions on the valvular surface and initiate an inflammatory response that leads to further fibrin deposition, thus leading to maturation of the lesions - these masses of fibrin and bacteria = vegetations
283
Q

What combination can be used which includes trimethoprim?

A

Co-trimoxazole:

  • Combination antibiotic with sulphamethoxazole
  • Significant additional toxicity
    • Bone marrow suppression
    • Stevens Johnson syndrome
  • Relatively few advantages
    • Used in certain uncommon infections by specialists
    • Pneumocystitis jjrovecii pneumonia (usually occurs in HIV)
284
Q

Explain AMR and one health

A
  • Dissemination of antibiotics and antibiotic resistance occurs within agriculture, community, hospital, waste water treatment and associated environments
  • Interconnection between human healthcare, animals, agriculture etc.
285
Q

How does traveller’s diarrhoea typically clinically present?

A
  • Often day 4-14 travel
  • Self limiting
    • 1 to 5 days
    • 8 to 15% last >1 week
  • Symptoms (ETEC)
    • Anorexia, malaise and abdominal cramps
    • Watery diarrhoea (no blood)
    • Fever nausea and vomiting
  • Unusual symptoms in travellers diarrhoea - tenesmus, rushing to toilet, blood in stool, lots of pain
    • More likely to indicate salmonella/shigella etc.
286
Q

Should a patient with suspected endocarditis be started on antibiotic therapy?

A
  • Depends on clinical assessment of how acutely ill the patient is - if not acutely unwell antibiotics are not indicated
  • Starting antibiotics too early will sterilise all future blood cultures - will need to treat empirically without positive cultures
  • Usually best to wait and identify a causative organism before starting antibiotic treatment
  • Make sure patient is monitored in case condition deteriorates
287
Q

How is a rapidly progressing/immediately life-threatening infection dealt with in primary care?

A

Rapid admission to hospital, consider pre-hospital Rx

288
Q

How does the number of reported penicillin allergies vary from the actual number of people with a penicillin allergy?

A
  • Reported allergy to beta-lactams very common - around 1:10 patients report penicillin allergy
  • Often reported hypersensitivity syndrome is non-allergic
    • GI symptoms
    • Therapeutic failure
  • Often reason for reported allergy is unclear
289
Q

When did ESBLs first emerge?

A
  • ESBL called CTX-M detected in early 1990s
  • Appeared simultaneously in Europe (Germany) and South America (Argentina)
  • CTX-M - cefotaximase-Munich
  • 4 month Munich child with Otitis media 1990
290
Q

Describe the development of C diff infection

A
  • Antibiotics cause reduced gut microbial species and diversity
  • Ingestion of C. diff spores from the environment - can be difficult to eradicate from hospitals
  • C diff spores germinate - dysbiosis of the gut microbiome
  • Development of C diff infection - severe diarrhoea, abdominal pain, nausea and fever, inflammation and cell death (can progress to pseudomembraneous collitis)
  • Has developed resistance to common antibiotic classes
291
Q

Describe the pathogenesis of septic arthritis

A
  • Develops as a result of haematogenous seeding or direct inoculation of bacteria into the joint
  • Most commonly via haematogenous seeding, the synovial membrane has no limiting basement membrane, allowing organisms to enter the joint space
    • Most commonly causes by organisms able to adhere to the synovial tissue e.g. staphylococcus aureus
  • Direct inoculation via trauma, arthroscopy or other surgery, intra-articular injection
292
Q

List the features of a systemic inflammatory response

A
  • 2 or more of
    • Heart rate >90bpm
    • Temp >38 or >36
    • Respiratory rate >20 per minute
    • WCC >12 or <4
293
Q

Which antibiotics are associated with causing the majority of C diff infections?

A

4Cs:

  • Clindamycin
  • Co-amoxiclav
  • Cephalosporins
  • Ciprofloxacin

All antibiotics can cause C diff - even those that treat it

294
Q

What are the main points from history/examination which would suggest inflammatory bowel disease in a patient with acute diarrhoea?

A

Often younger patient with bloody diarrhoea

Will often give a history of an irritable bowel, may have weight loss

295
Q

What investigation is important in MRSA bacteraemia?

A

Risk of endocarditis - need echo and ECG

ECG - assess the PR interval, may be prolonged if valvular abscess present

296
Q

List the clinical features of Dengue fever

A
  • ‘Breakbone’ fever
    • Headache
    • Fever
    • Retro-orbital pain
    • Arthralgia/myalgia
    • Rash - sunburn-like
    • Cough
    • Sore throat
    • Nausea
    • Diarrhoea
  • Laboratory
    • Leucopenia
    • Thrombocytopenia
    • Transaminitis
297
Q

Define minimum inhibitory concentration

A
  • Minimum dose of antibiotic required to inhibit growth of bacteria
    • E-strip with low to high concentration of antibiotics
    • Solution of bacteria onto agar plate - growth where not inhibited by antibiotics
    • Number on scale = MIC
298
Q

How long should antibiotics be prescribed for in lower UTIs?

A
  • Females - 3 days
  • Males - 7 days
299
Q

List the important beta-lactam antibiotics

A
  • Penicillins e.g.
    • Benzylpenicillin
    • Flucloxacillin
    • Amoxicillin
  • Cephalosporins e.g.
    • Ceftriaxone
  • Carbapenems e.g.
    • Meropenem
  • Monobactams - Aztreonam
300
Q

Describe the treatment of an uncomplicated UTI

A
  • Treatment only needs to sterilise urine - no need for systemic activity
  • Low risk infection so can often wait for culture results
  • Antibiotics - trimethoprim or nitrofuratoin
  • Trimethoprim
    • Currently 1st line for most causes
    • Avoid in 1st trimester of pregnancy - weak anti-folate action
    • Penetrates well into prostate so good for men
    • Lots of resistance
  • Nitrofuratoin
    • Excellent broad spectrum of activity
    • Concentrated in urine so no effect on other tissues
    • Failure to concentrate in urine in renal failure - avoid
    • Relatively non-toxic in short courses
      • Pulmonary fibrosis with long term use
    • Used in pregnant women
301
Q

Describe the treatment of haemophilus influenzae

A
  • Amoxicillin
  • Risk of beta lactamase - 1 in 3 have penicillin resistance
    • Co-amoxiclav
    • Macrolides (clarithromycin)
    • Tetracyclines (doxycycline)
302
Q

What is the first line treatment of an uncomplicated UTI?

A
  • Trimethoprim
  • Not amoxicillin - not active in causative organisms
  • Not ciprofloxacin - too much harm
  • Not gentamicin - too toxic, must be given IV (not useful in primary care)
303
Q

What factors contribute to the spread of infection?

A
  • Infectious agent
  • Reservoirs
  • Portal of exit
  • Means of transmission
  • Portal of entry
  • Susceptible host
304
Q

How can the likelihood of a positive blood culture result being a contaminant be determined?

A
  • Contaminants picked up from skin, more likely if there was inadequate skin preparation before taking the culture
  • Coagulase-negative staphylococci are the most common contaminant, not significant in the absence of any long lines e.g. venous pressure line or prosthetic devices e.g. heart valves - good at attaching themselves to foreign bodies and causing infection
  • Contaminants usually found in one bottle of a blood culture pair - if all 3 sets of blood cultures are positive the culture is highly likely to be significant
305
Q

How are viral haemorrhagic fevers treated?

A
  • Supportive
  • Corrective coagulopathy/anaemia
  • Ribavirin - anti-viral
306
Q

Describe the typical clinical presentation of mycoplasma pneumoniae

A
  • Can be non-specific (atypical)
    • Myalgia, arthralgia - presents with flu-like symptoms
  • On examination/CXR find consolidation
  • Can get more generalised manifestations (not just respiratory)
    • Haemolysis (cold agglutinins)
    • Guillain-Barre
    • Erythema multiforme
    • Cardiac - conduction problems e.g. heart block
    • Arthritis
307
Q

What are the sources of ESBL resistance?

A
  • Environmental Kluyvera spp.
  • Spread of resistance genes into E. Coli, klebsiella and enterobacter
  • Spread to/from - household members and pets, animals and via food/travel
    • Risk of spread when travelling dependent on travel destination, length of stay, visiting friends and relatives and type of food (ice cream and pastries)
308
Q

Give an example of gram negative cocci and describe their apearance

A

Neisseria species - kidney bean shaped

309
Q

Describe the typical dosing schedule of gentamicin

A
  • Once daily dosing
    • Give high initial dose to take advantage of rapid killing
    • Leave long dosing interval (24-48hrs) to minimise toxicity - less opportunity to accumulate
  • Measure trough level to ensure drug not accumulating
  • Give for 3 days only
310
Q

Describe the action and toxicity of tetracyclines

A
  • Similar spectrum of activity to macrolides
  • Also active against atypical organisms
  • Relatively non-toxic
  • Avoid in children and pregnant women
    • Bone abnormalities
    • Tooth discolouration
311
Q

Describe the toxicity of trimethoprim

A
  • Usually more toxic in more co-morbid patients
  • Elevation of serum creatinine
    • Does not reflect fall in GFR
    • Related to action on proximal tubules
  • Elevation of serum K+
    • Problematic in patients which chronic renal impairment
  • Rash and GI disturbance relatively uncommon
312
Q

What are the consequences of malaria infection?

A
  • Red blood cells aggregate, microcirculation clogged
  • Renal failure, lactic acidosis (hypoxia), cerebral malaria, pulmonary oedema
  • Don’t become unwell until red cells are parasitised
313
Q

Give examples of antibiotics which act by inhibiting folate synthesis

A

Trimethoprim

Metronidazole

314
Q

What would be the appropriate initial treatment for suspected cellulitis?

A
  • Antibiotics - IV flucloxacillin and benzylpenicillin
  • Analgesia - NSAIDs have been associated with necrotising fasciitis and should be witheld, co-codamol is appropriate
  • Area of erythema should be marked and closely monitored overnight
315
Q

How is empirical antibiotic therapy used clinically?

A
  • Use antibiotic which has extensive action against any bacteria which might be causing infection (broad spectrum)
  • Need to penetrate broadly throughout body
  • Accept that impact on colonisation and resistance may be greater
316
Q

What property allows bacteria to evolve quickly to changing environments?

A

Very short generation times - 20-30 minutes

317
Q

Why are ESBLs a problem?

A

Resistant to most antibiotics - few left able to treat them

318
Q

List the risk factors for bacterial pneumonia

A

Alcoholism

Smoking - destroys host defence

Immunosuppression e.g. cancer, HIV

Airways disease - asthma, COPD

Flu infection

319
Q

What is the classical presentation of streptococcus pneumoniae?

A
  • Abrupt onset
    • Cough
    • Fever
    • Pleuritic chest pain (inflamed lung rubbing on pleura)
  • Dull percussion
  • Coarse crepitations
  • Increased vocal resonance
  • Basal consolidation on X-ray
320
Q

What are beta-lactamases?

A
  • Enzymes that lyse and inactivate beta-lactam drugs
  • Commonly secreted by gram -ves and S. aureus
  • Confer high level resistance to antibiotic - total antibiotic failure likely to result
321
Q

In what environment is exposure to viral haemorrhagic illness most likely?

A

Rural > urban

322
Q

Which infections is ceftriaxone usually used to treat?

A

CNS infections caused by strep, neisseria and haemophilus bacteria

323
Q

Which antibiotics are not considered safe in pregnancy?

A
  • Tetracyclines - bone/tooth abnormalities
  • Trimethoprim - neural tube defects (1st trimester)
  • Nitrofurantoin - haemolytic anaemia (3rd trimester)
  • Aminoglycosides - ototoxicity (2nd/3rd trimester)
  • Quinolones - bone/joint abnormalities
324
Q

How is legionella pneumophila diagnosed?

A

Culture

Serology

Urinary antigen test

325
Q

Why is antimicrobial resistance so challenging to overcome?

A
  • AMR is ancient >30,000 years old
  • Microbiome
    • 100 trillion microbes
    • 10 xs number of human cells
    • Infinite opportunities for AMR
326
Q

What surgical management should be used in acute cholecystitis?

A

ECRP - endoscopic retrograde cholangio-pancreatography

327
Q

Describe the pharmacology of beta-lactams

A
  • Most are poorly absorbed from the GI tract - must be given IV
    • Amoxicillin, flucloxacillin are effective orally - vomiting limits dose
  • Usually excreted unchanged in urine, some also via bile
  • Half life varies
    • Benzylpenicillin = 1 hour
    • Ceftriaxone = 8 hours
  • Usually effectively distributed to sites of infection - can penetrate joints, meninges etc.
328
Q

Describe the reservoir of and illness caused by salmonella sp.

A

Poultry

Loose stool and nausea, colic

329
Q

When is metronidazole commonly used?

A

Often added to therapy in intra-abdominal infections, esp abscess

330
Q

List parasitic causes of traveller’s diarrhoea

A

Giardia

Cryptosporidium

Cyclospora

Microsporidia

Isospora

Entamoeba histolytica

331
Q

Which bacteria are sensitive/resistant to clindamycin?

A

Highly sensitive - bacteroides, clostridium, streptococcus, staphylococcus

Resistant - enterococcus, E. coli and other coliforms, neisseria, haemophilus, pseudomonas

332
Q

What should be included in a history from a patient with suspected pneumonia?

A
  • Symptoms:
    • Fever
    • Cough/sputum
    • Chest pain
    • Insidious/abrupt onset
    • Non-respiratory symptoms
  • Past medical history
    • Underlying lung disease
    • Immunosuppression
  • Epidemiology
    • Ill contacts
    • Travel
    • Water exposure
333
Q

How long should antibiotics be prescribed for in bacterial meningitis and what is this determined by?

A

7-21 days, determined by the causative organism

334
Q

What is the likely source of bacteraemia in acute cholecystitis?

A

Intra-abdominal/biliary source

335
Q

Give examples of infectious agents and their portals of exit

A
  • TB - respiratory tract
  • Salmonella - faeces
  • Norovirus - vomit
  • Blood borne viruses - cuts and injuries
  • Enterovirus - conjunctival secretions
336
Q

Describe the toxicity of vancomysin

A
  • Nephrotoxicity - more likely with higer doses
  • Red-man syndrome if injected too rapidly - anaphylactoid reaction, very rare now infusion rates slow
  • Ototoxicity - rare
  • Therapeutic drug monitoring undertaken - narrow therapeutic range, aim higher in severe illness
337
Q

Describe the type IV hypersensitivity reaction which can occur in response to beta-lactams

A

Stephen Johnson’s syndrome - widespread rash, mucosal ulceration of mouth and genitals

338
Q

What are the most common illnesses in returning travellers?

A
  • 34% diarrhoea
  • 23% non-specific fever
  • 19.5% dermatological - mostly sunburn, some parasites
  • Respiratory - mostly influenza
  • Neurologic - encephalopathy
  • GU, STI
339
Q

Which bacteria are sensitive/resistant to aztreonam?

A

Highly sensitive - E. coli, neisseria, haemophilus, pseudomonas

Sensitive - other coliforms

Resistant - staphylococcus, enterococcus, streptococcus, clostridium, bacteroides

No gram +ve activity

340
Q

How is a positive blood culture result be interpreted and acted on?

A

There are three questions to consider when you get a positive blood culture result:

  1. Is the isolate a contaminant from skin?
  2. If it is not a contaminant, what is the source of the bacteraemia?
  3. What antibiotic(s) would be most appropriate according to the source?
341
Q

In what common situations should an antibiotic not be prescribed?

A
  • Community > hospital
    • Viral + self-limiting bacteria respiratory tract infections
    • Otitis media, sinusitis, lower respiratory tract infections, COPD, upper respiratory tract infections, diarrhoea
    • Evidence shows antibiotic no better than placebo in LRTI in primary care
  • Asymptomatic bacteruria, uncomplicated cystitis
  • In-growing toe nails
  • Leg ulcers without cellulitis
  • Varicose eczema (mistaken for cellulitis)
  • Systemic inflammatory response due to cancer, ischaemia, inflammation
342
Q

Give an example of intrinsic resistance of a bacteria

A

Vancomycin is inactive against Gram negative bacteria (cell wall structure not suitable target)

343
Q

What are the modern uses of chloramphenicol?

A
  • Topical therapy for eyes e.g. bacterial conjunctivitis
  • Bacterial meningitis with beta-lactam allergy
344
Q

Where are streptococci species normally found?

A

Usually found on the skin or in the respiratory tract

345
Q

Describe methods of malaria prevention

A
  1. Bite prevention
  2. Chemoprophylaxis
  • Mefloquine
    • Once weekly - good if long treatment/in children
    • Psychiatric side effects - vivid dreams –> psychosis/severe anxiety
  • Doxycycline
    • Antibiotic
    • Daily
    • Photosensitisation - sunburn
    • Thrush, dyspepsia
  • Malarone
    • Minimal side effects - GI upset, mouth ulcers
    • Much more expensive - £28/week
346
Q

How is the clinical severity of pneumonia determined?

A

Severe pneumonia =

  • CURB65 Score >2 -

C - confusion

U - urea >7

R - respiratory rate >30

B - BP, diastolic <60 or systolic <90

65 - age over 65 years

OR

  • Multilobar consolidation on CXR and/or hypoxia on room air

Sepsis - qSOFA

  • Systolic BP <100mmHg
  • Altered mental status
  • Respiratory rate >22 breaths/min
347
Q

What antibiotics would be used to treat an MRSA wound infection?

A

IV vancomycin +/- oral rifampicin, fusidic acid, doxycycline or trimethoprim or oral linezolid or IV daptomycin or IV tigecycline

348
Q

What is usually the first observation to decompensate when a patient is severely ill?

A

Respiratory rate usually decompensates first

In young healthy patients heart rate and BP are usually maintained until they are very unwell

349
Q

Define broad spectrum antibiotics and give an example

A
  • Antibiotics that are active against a wide range of bacteria
  • Treat most causes of infection but also have a substantial effect on colonising bacteria
  • E.g. Meropenem
    • Active against almost all gram positive and negative species
    • Resistance is rare except for MRSA
350
Q

Define narrow spectrum antibiotics and given an example

A
  • Antibiotics that are active against a limited range of bacteria
  • Useful only where the cause of the infection is well defined
  • Have a much more limited effect on colonising bacteria
  • E.g. Benzylpenicillin
    • Highly active against streptococci
    • Most other disease causing bacteria are resistant
351
Q

How many deaths globally are attributable to infectious diseases?

A

20% - 10 million deaths/year

Medicine Year 3 (15 decks)

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