Microbiology Flashcards

1
Q

State the components and the functions of the human microbiome

A

1000 species: bacteria, fungi and viruses

Variability of species between individuals, but a consistent range of functions at given body sites

people never exposed to antibiotics have a bigger range of distinct species making up their microbiome

Where is it?

  • on and within our bodies
  • at the interfaces between self and non self
  • at our interface with the environment
  • def of ecosystem: a system formed by the interaction of a community of organisms with its environment

Where is it not: blood lypmh etc. we talk in the lab about sterile sites:

Components:
SITE - SPECIES - PHYLUM:
GI - Bacteroides - Bacteroidetes
Urogenital (female) - Lactobacilli - Firmicutes
Skin - Proprionibacterium - Actinobacteria
Oral - Streptococci - Firmicutes
Nasal - Staphylococci - Firmicutes

May be different levels of bacteria in different areas in different people but still the same physiological functions happen there

WHAT DOES IT DO?

  • nutrition
  • metabolism
  • immune programming - almost definitely does this function - bacteria instruct immune system about pathogens
  • inflammatory modulation - speculation with this
  • innate immunity - done by out performing pathogens - grow so that bad bacteria can’t grow there instead so in this way it keeps it healthy
  • may have something to do with CNS and brain development?
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2
Q

Review the key stages in the acquisition of the human microbiome

A

Birth is Critical:
vaginal microbiota - first organisms you acquire during birth - vaginal mucous gets squeezed into mouth as it is being squeezed through - first gasp - inhales the mucous and some is swallowed

Prenatal:
Maternal diet, maternal GI and vaginal microbiota, antibiotics

Perinatal:
Mode of delivery, skin, antibiotics

Postnatal
Environment, people, feeding, antibiotics

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3
Q

what is the significance of Proteus, Providencia, and Morganella species in urine

A
  • Associated with renal calculi
  • Express urease enzyme which converts urea to ammonia
  • Ammonia alkalises the urine, causing precipitation of struvite crystals
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4
Q

what is the significance of yeast in the urine

A

Candida species from children’s urine should prompt a search for fungal balls in the bladder

These patients require surgical removal of fungal balls

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5
Q

what is a UTI

what is a lower uti and an upper uti

A

UTI: an inflammatory response of the urothelium to bacterial invasion that is usually associated with bacteriuria and pyuria.

Lower UTI: infection between the urethra and the ureterovesical junction

Upper UTI: infection above the ureterovesical junction

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6
Q

describe the pathogenesis of uti

A

Infection of the urinary tract occurs when

  1. Pathogen virulence increases

and/or

  1. Host defence mechanisms decrease - decreased urine flow

Pathogen factors in UTI:
Uropathogens survive and invade by virtue of their virulence factors
An ‘arsenal of weapons’ against the host:
- Motility mediator – flagella powers bacteria’s directional movement
- Adhesins – fimbria allow attachment to host epithelium
- Invasins – proteases break down host epithelial barrier
- Toxins – destroy host tissues and cause systemic instability
- Immune escape mediators – disguise bacteria from immune recognition
- Biofilm production – shield bacteria from immune attack - live in colonies - communities

Normal flora of the periurethral area (e.g. lactobacilli, coagulase negative Staphylococci) inhibit colonisation with uropathogens 
Factors which alter this flora:
- Systemic antibiotics 
- Prolonged hospitalisation
- Spermicides (nonoxynol-9)
- Oestrogen deficiency - pre menstruation and end of fertile period (menstruation)
- Low vaginal pH
- Low cervical IgA
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7
Q

how would you investigate urethritis

A

Urine for microbiological culture
Urine or swab for PCR detection of Chlamydia or Gonococcus
Gram stain of a purlulent discharge can reveal gonococcus (Gram negative cocci inside epithelial cells)

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8
Q

name some of the risk factors of cystitis

A
Ineffective voiding:
Bladder outflow obstruction (e.g. prostate enlargement, tumour, clots, cystocoele)
Memory impairment (Alzheimer’s disease)
Neurological deficit (Stroke, Parkinson’s disease, spinal cord injury)

Smoking:
- Causes a chemical interstitial cystitis

Diabetes mellitus
- Raised urinary glucose feeds bacterial growth

Sexual intercourse
- Delivers pathogens to urethral entry

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9
Q

describe the presentation of cystitis

A

Urinating that is:

  • Painful (dysuria)
  • Frequent (urinary frequency)
  • Urgent (urinary urgency)

Urine that is:

  • bloody (haematuria)
  • turbid
  • foul-smelling

General/nonspecific symptoms:

  • Fever
  • Confusion
  • Abdominal pain
  • these are important in young - can’t tell you what’s happening
  • ppl who have cognitive impairment - can’t tell you
  • ppl with a catheter in - can’t see urine cuz they aren’t urinating
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10
Q

describe how you would investigate cystitis

A
Urinalysis
       Nitrites, leucocytes, blood
Urine microscopy
       Pyuria, bacteriuria
Urine for organisms and sensitivities (O&S)
>100,000 organisms/ml is significant
Imaging 
Ultrasound or CT renal tracts
Indicated if recurrent or complicated cystitis for:
Anatomical abnormality 
Renal stones 
Tumours
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11
Q

describe the management of cystitis

A

Good hydration

Glycaemic control in diabetes

Antibiotic therapy:
Several oral options available:
all taken for 3 days
- Nitrofurantoin 
- Trimethoprim			
- Pivmecillinam				
- Cephalexin (useful in pregnancy)

Fosfomycin 3g single dose

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12
Q

describe prophylaxis of cystitis

A

Genital hygiene

Post-coital voiding

Avoidance of diaphragm/spermicide

Estriol vaginal cream (post-menopausal)

Insufficient evidence for:
Cranberry juice
‘Wiping front to back’
Clothing

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13
Q

describe the risk factors associated with pyelonephritis

A

Cystitis:

  • 50% of cases results in upper UTI - infection rises up
  • Ureterovesical junction can be compromised through bladder oedema

Interference with ureter peristalsis:

  • Pregnancy
  • Stones
  • Strictures
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14
Q

describe presentation of pyelonephritis

A

= Symptoms of cystitis

PLUS classical triad of:

Fevers/rigors

Flank pain

Nausea and vomiting

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15
Q

describe investigation of pyelonephritis

A

Same measures as for cystitis
(e.g. urine culture and sensitivities)

Blood cultures

Imaging
USS or CT renal tracts

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16
Q

describe management of pyelonephritis

A
  1. Resuscitation
  2. Empirical antimicrobial therapy:
    - (after cultures taken) - before you get the results
    Several options available:
    - IV Piperacillin-Tazobactam
    - IV/PO Ciprofloxacin
    - IV Gentamicin
  3. Targeted antimicrobial therapy
    - (when culture results available) - amend the empirical antibody treatment and make it more specific because you now have the results
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17
Q

what is the difference between a complicated and uncomplicated UTI

A

Uncomplicated UTI: an infection in a healthy patient with a structurally and functionally normal urinary tract.

Complicated UTI: infection associated with factors that increase the chance of acquiring bacteria and decrease the efficacy of therapy:

  • Structural or functional abnormality of the urinary tract
  • Immunocompromised host
  • Hypervirulent or resistant bacteria
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18
Q

who needs antibiotic treatment for Asymptomatic bacteriuria

A

Pregnant women:

  • x30 risk of pyelonephritis compared to non-pregnant matched patients
  • associated with premature labour and low weight babies

Patients awaiting urological surgery or procedure:

  • 60% of bacteriuric patients will have bacteraemia post-instrumentation of their renal tract
  • 10% of these will develop sepsis
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19
Q

who needs antibiotic treatment for Asymptomatic bacteriuria

A

Pregnant women:

  • x30 risk of pyelonephritis compared to non-pregnant matched patients
  • associated with premature labour and low weight babies

Patients awaiting urological surgery or procedure:

  • 60% of bacteriuric patients will have bacteraemia post-instrumentation of their renal tract
  • 10% of these will develop sepsis
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20
Q

Compare the fundamental differences between a bacterial and a viral
infection

A

Bacterial:

  • they are cells
  • adhere to host tissue
  • invasiveness - penetrate into the cells and their epithelia
  • evasion of host defences - can disguise or cloak themselves
  • toxins

viruses:
obligate intracellular parasites - need a cell for the virus to live in
- needs receptor at site of entry to the body
- dissemination - spreading
- multiplication in target organs - this can kill the cell - adds to damage virus is causing
- shedding - enter cell - multiply then leave cell

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21
Q

define serotype

A

Classification of organisms according to antigenic properties

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22
Q

describe how the gram stain works

A

needed because bacterial cells are transparent

  • first stain is crystal violet and iodine
  • these bind to peptidoglycans on the cell wall
  • acetone washes away this stain from gram negative but doesn’t wash it away in gram positive
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23
Q

describe how the gram stain works

A

needed because bacterial cells are transparent

  • first stain is crystal violet and iodine
  • these bind to peptidoglycans on the cell wall
  • acetone washes away this stain from gram negative but doesn’t wash it away in gram positive (because gram positive have thicker peptidoglycan walls and negative have their cell membrane washed away by acetone)
  • neutral red is a counter stain
  • applied second
  • gram positive stays purple because it already has the violet/iodine stain
  • gram negative takes up the counter stain and show up pink-red
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24
Q

when classifying bacteria what is the difference between cocci and rods

A
cocci = ball like
rods = longer thinner

these are then gram negative or positive

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25
name some gram positive cocci and rods name some gram negative cocci and rods
lecture 2 slide 7 on notability
26
what does a classification of obligate anaerobe mean
has to live in anaerobic conditions
27
what does a classification of obligate aerobe mean
has to live in aerobic conditions
28
what does a classification of facultative anaerobe mean
will grow in presence or absence of oxygen slight preference to low oxygen environments most medically important bacteria in this category highlights how adaptive they are
29
name 5 methods to categorise bacteria
Staining characteristics - gram stain Growth characteristics- Aerobic/ Anaerobic Haemolysis on blood agar Metabolic activity- Coagulase/ Catalase/ Oxidase Antigenic features - ‘Serotyping’ Nucleic acid molecules - ‘Genotyping’
30
where might some gram positive cocci clusters be found in the body
Skin, nasal, desquamated squames- dust
31
where might you find B-haemolytic Streptococci: (Lancefield group A, B, G) Streptococcus oralis Streptococcus pneumoniae
Mouth, upper respiratory tract
32
where might you find Enterococcus faecalis
GI Tract
33
where might you find Clostridium tetani Clostridium difficile Clostridium perfringens
Soil. Anaerobic, spore forming, bacteria
34
where might you find Listeria monocytogenes Bacillus species
Food
35
where might you find Proprionibacterium acnes
skinf
36
where might you find Lactobacillus acidophilus
Food, female GU tract
37
where might you find Neisseria meningitidis
Upper respiratory tract
38
where might you find Neisseria gonorrhoeae
Genito- Urinary tract
39
where might you find Haemophilus influenzae
Respiratory tract
40
where might you find Escherichia coli Klebsiella pneumoniae Proteus mirabilis Salmonella enteritidis Bacteroides fragilis
Gastro-intestinal tract: mammalian
41
where might you find Pseudomonas aeruginosa
Aquatic environments
42
where might you find Campylobacter jejuni
Gastro-intestinal tract: Avian
43
where might you find Mycobacterium tuberculosis
TB. ‘acid and alcohol fast bacilli’: Respiratory tract
44
where might you find Legionella Pneumophila Chlamydia Trachomatis Mycoplasma pneumoniae
Cell wall deficient bacteria: - Legionella: aquatic and respiratory tract - Chlamydia: respiratory and GU tract - Mycoplasma: respiratory tract
45
where might you find Treponema pallidum
Syphillis. Spirochaete (spiral bacteria) GU tract
46
name some DNA viruses, RNA viruses and reverse transcribing viruses
see lecture 2 slide 24 notability
47
Evaluate the use of white cell count and differential, C-Reactive Protein and Temperature to detect and monitor infection
CRP one of many acute phase proteins: made by the liver and believed to modulate inflammation and tissue repair These markers can help confirm or refute a diagnosis of infection, but cannot be definitive. They may just indicate Inflammation temp can indicate inflammation can indicate infection possibly but not always as temp can vary naturally or could be something other than infection such as cancer connective tissue disease or drug reaction
48
what does transmissibility mean
ability to be transmitted
49
what is meant by incubation period
the time between exposure to a pathogen and when symptoms are first apparent. Typically the period taken by the multiplying organism to reach a threshold necessary to produce symptoms in the host
50
what is meant by infectious period
period infected person can transmit infection to susceptible host
51
what does transmissibility mean
ability to be transmitted | how contagious it is
52
what are the cardinal signs of inflammation
``` Rubor - redness Calor - heat Tumour - swelling Dolor - pain functio laesa - loss of function ```
53
define sepsis
‘Sepsis is characterised by a life-threatening organ dysfunction due to a dysregulated host response to infection’
54
what is the difference between sensitivity and specificity in diagnostic tests
seNsitive test has v low false Negative rate sPecific test has a low false Positive rate
55
what are positive and negative predictive values in diagnostic tests
* Positive Predictive Value: the probability that the person with a positive test result has the disease - want this to be high then you'll have a lot of confidence * Negative Predictive Value: the probability that the person with a negative test result does not have the disease - want this to be high as well
56
what is the difference between direct and indirect tests
Direct- detect an organism, or a part of an organism - E.g: • Microscopy- view directly using light or electron microscopy, (generally following Gram staining) • Culture- the growing of an organism in a controlled environment • Toxin detection- identify a pre-formed toxin associated with a specific organism • Antigen detection- using immunological methods to identify a antigen specific to an organism • Nucleic acid amplification test (NAAT)- detect nucleic acid sequence specific to an organism Indirect- detects an element of the hosts specific, adaptive immune response to an organism. - eg looking for the antibodies raised against the organism - referred to as serology or serological tests
57
describe how a direct toxin detection or direct antigen detection test work using enzyme immunoassay (EIA)
see microbiology 4 - diagnosing infection - slide 10 A specific antibody is bound to the test bed (‘solid phase surface’ in step 1). Then the patient sample is added (step 2). If the antigen is present in the patients faeces it binds to the antibody. We then add a second antibody which binds to the antigen in the sample. This second antibody has an enzyme label attached to it (‘e’)- step 3. Then some chromogenic (colour generating) substance is added- if the enzyme ‘e’ is present there will be a colour change. This can be detected by a machine reader, or in the example about a little cassette is used which can read by eye.
58
Describe Upper Respiratory Tract (URT) infections with examples
- above larynx = upper respiratory tract infection - below larynx = lower respiratory tract infection examples: colds / sinusitis / otitis media / mumps / pharyngitis / epiglottitis ``` Common cold: > e.g: - rhinoviruses - coronaviruses - adenoviruses ``` - mucosal irritation - sneezing and coughing - symptoms - this can help spread the disease often trigger LRTI
59
describe Acute Epiglotitis
* Young children * Medical emergency! * Respiratory obstruction * Intubation and antibiotics required * Blood culture often positive Used to be common but Hib vaccine has largely eliminated this condition cause: - Haemophilus influenzae capsular type B
60
describe sinusitis
URTI * All ages * Facial pain * Localised tenderness * Fever Viruses: - Streptococcus pneumoniae - Haemophilus influenzae
61
describe Acute Epiglotitis
URTI * Young children * Medical emergency! * Respiratory obstruction * Intubation and antibiotics required * Blood culture often positive Used to be common but Hib vaccine has largely eliminated this condition cause: - Haemophilus influenzae capsular type B
62
describe mumps
URTI - Parotitis - swelling of parotid salivary gland - Respiratory spread - No specific treatment - Vaccine preventable (MMR) but seems to be less effective in recent years Diagnosis: - RT-PCR for mumps RNA in saliva, (or buccal swab) or urine
63
describe Infectious mononucleosis (IM)
URTI Epstein Barr Virus- Herpes family – Transmitted in saliva- infects B lymphocytes – Teenagers and young adults get IM – Babies get asymptomatic infection Fever, sore throat, lymphadenopathy Splenomegally, lethargy, hepatitis Symptoms immunologically mediated Blood white cell changes test: Monospot serology test Or EBV IgM Complications rare – eg encephalitis, nearly always with complete recovery No specific treatment
64
describe Streptococcus pyogenes
URTI • Pharyngitis- manifests as sore throat & fever – Peritonsillar abscess ('quinsy') - scarlet fever – Rheumatic fever. – Rheumatic heart disease – Acute glomerulonephritis. DIAGNOSIS – (1) Throat Culture (2) ASOT (Anti-streptolysin O titre)(serology) Treatment – Penicillin (Erythromycin)
65
describe Diphtheria
URTI Corynebacterium diphtheriae - Gram positive bacillus * Pharyngeal diphtheria. – pseudomembrane * toxin can cause fatal heart failure and a polyneuritis * Toxin is phage coded Disease of the past here but still prevalent in other areas of the world. - Effective vaccine. - Treatment – antitoxin (antibody) + Penicillin or Erythromycin
66
describe Laryngitis and tracheitis
Inbetween upper and lower RTI * Common & lots of causes * One example is Croup - Inbetween upper and lower RTI * Croup = laryngotracheobronchitis causing inspiratory stridor due to laryngeal narrowing – young children Caused by Parainfluenza viruses 1&2 Diagnosis: - PCR - But mostly clinical diagnosis treatment: - Paracetamol & fluids - Corticosteroids if severe - Adrenaline if hospitalised
67
describe Bordetella pertussis (whooping cough)
LRTI gram negative coccobacillus Catarrhal illness then paroxysms of coughs. – Followed by a 'whoop' sound due to inspiratory gasp of air. – Can go on for weeks – “100 day cough” – Most severe in young babies Lobar or segmental collapse of the lungs can occur * Spread from person to person by air-borne droplets. - quite infectious * Attach to respiratory epithelium. treatment: - macrolide - (also prophylaxis for contacts can be given) - Immunisation – acellular vaccine.- seen re-emergence lately though
68
describe acute bronchitis
LRTI inflammation of mucous membranes in the bronchial tubes Viral = Non-productive cough Bacterial = Productive cough often viral virus can trigger a subsequent bacterial infection Acute exacerbation of chronic bronchitis - COPD (Chronic obstructive pulmonary disease)
69
describe bronchiolitis
LRTI • RSV (Respiratory Syncitial Virus) is the main agent • <2 years of age- narrow bronchioles. • Wheezy presentation – Cough, wheeze, low O2,raised resp rate, cyanosis, consolidation • => interstitial pneumonia.
70
describe RSV (Respiratory Syncitial Virus)
* Transmitted by large droplets and by hands. * October – February * About 1 in every 100 infants with RSV bronchiolitis or pneumonia requires admission to hospital. * Severe in children with heart and lung problems – these are given prophylatic paluvizumab each winter * Paluvizumab is a monoclonal antibody specific to RSV * Treatment – ribavirin if severe / life threatening
71
describe typical pneumonia
• Classical scenario is lobar pneumonia due to Streptococcus pneumoniae: – Lobar pneumonia- clinical and radiological – Positive blood cultures – Productive cough- Rust coloured sputum • Gram stain – polymorphs and gram positive diplococci • Culture – pneumococcus • Pneumococcal Urinary antigen
72
describe atypical pneumonia
– “atypical agents” • E.G. Mycoplasma pneumoniae, • Chlamydophila pneumoniae, Chlamydophilia psittaci, Legionella pneumophila, Coxiella burnetii (Q fever) Mycoplasma pneumoniae – “atypical symptoms” • Extrapulmonary symptoms • Little or no sputum – Dry cough • No evidence of lobar consolodation
73
describe TB
Mycobacterium tuberculosis * Primary infection often asymptomatic * Dormancy and reactivation * Diagnosis: - Zeihl Neelson stain on sputum- Quick - not very sensitive - Culture – Slow – weeks – special media - PCR Treatment: - 3 drug combination to prevent resistance - resistance is increasing and is problematic - Prolonged course – months.
74
name some bacteria that cause intoxication and then some that cause infection
Intoxication: Bacillus cereus Staphylococcus aureus Clostridium perfringens Clostridium botulinum ``` Infection: Salmonella Shigella Escherichia coli Vibrio cholerae Campylobacter Clostridium difficile Listeria monocytogenes ```
75
describe salmonella and how it causes infection
gram negative rods from family of Enterobacteriaceae over 2000 different serotypes not a normal inhabitant of the gut 2 main syndromes: >ENTEROCOLITIS: - a zoonosis - acquired from a non human animal - lots of different serotypes - eg S. typhimurium & S. enteritidis - transmitted to humans via contaminated food - Incubation Period 6h-2d - Symptoms: nausea, vomiting, abd. cramps, and non-bloody diarrhoea - Duration 2-7d - Diagnosis: Culture on selective media or PCR - Treatment - fluid and electrolyte replacement, only antibiotics if immunocompromised >ENTERIC FEVERS: - human infections - host is humans - eg Salmonella typhi and Salmonella paratyphi - human to human transmission - Incubation Period 10 to 14 days - much longer than enterocolitis - Symptoms: fever with headache, myalgias, malaise can be severe sepsis - Duration = 1 week followed by diarrhoea - Diagnosis: Culture on selective media
76
describe shigella and how it causes infection
Gram –ve rods- enterobacteriacea bacillary dysentery human pathogen spread by feral-oral route v small infectious dose - so therefore v infectious - four species - S. dysenteriae; the most serious - Most cases in UK caused by S. sonnei - Primarily a pediatric disease (& causes outbreaks in childcare facilities) - Short IP- diarrhea is watery initially, but later contains mucus & blood & pus- abdominal cramps & fever - Antibiotics should only be given for severe shigella diarrhoea – susceptibility testing important - variability in terms of what antibiotics shigella are sensitive to
77
describe Escherichia coli and how it causes infection
- Gram –ve rods - enterobacteraceae - some strains are normal gut flora others cause infections - Six distinct groups of E. coli with different pathogenetic mechanisms some invasive, others toxigenic - ETEC enterotoxigenic E.coli (cause traveller’s diarrhoea) - EPEC enteropathogenic E.coli (cause diarrhoea in babies ) - EHEC enterohaemorrhagic E.coli Haemolytic uraemic syndrome - Associated with eating undercooked, ground beef & raw milk or contact with animals - Cause bloody diarrhoea with abdominal cramps but no fever (HC) - can cause complication of HUS (Haemolytic Uremic syndrome) - Specific tests to identify strains of pathogenic E. coli - can be difficult - Antibacterial therapy- not indicated
78
describe cholera
- acute infection - caused bu comma-shaped gram negative bacterium V. cholerae serotype 01 - symptoms due to enterotoxin - Toxin causes fluid loss & painless, profuse, watery diarrhea * Can cause death by dehydration and electrolyte imbalance if untreated * Treatment: fluid replacement critical - Infection acquired from contaminated water supplies
79
describe campylobacter and how it causes infection
Curved or S-shaped Gram negative rods The most common cause of food-associated diarrhoea in UK Most human illness is caused by one species, C jejuni come from non human animals Campylobacter enteritis: - duration of symptoms 1 week - fever - abdominal pain - blood in faeces - rare complication: Guillain- Barre syndrome
80
describe Clostridium difficile and how it causes infection
Gram +ve anaerobic rods- spore forming Component of normal gut flora ; flourish under selective pressure of antibiotics (broad-spectrum) person to person spread common cause of hospital acquired infectious diarrhoea this is a cause of Antibiotic-associated diarrhea - produces an enterotoxin and cytotoxin - can cause Pseudo-membraneous colitis- can be rapidly fatal - Diagnosis : detection of toxin in faeces - Treatment: > Stop antibiotics > Oral metronidazole or vancomycin ..or oral fidaxomicin ``` BNF treatment: • First line: - Oral metronidazole 10–14 days • If recurrent or non responding: - oral vancomycin 10–14 days • For infection not responding to vancomycin, or for life-threatening infection, or in patients with ileus: - oral vancomycin + iv metronidazole • Difficult situations: - Oral fidaxomicin – expensive - Faecal matter transplant ```
81
what are the two main viruses associated with viral diarrhoea
Rotaviruses & Norovirus
82
what are the main symptoms of viral diarrhoea
watery diarrhea and vomiting.
83
describe rotavirus
``` • Mainly diarrhoea • <2 years of age • Severe presentation –dehydration common, major killer in 3rd world • Incubation 1-2 days • Duration ~ 4 days - diagnosis: – Viral particles can be seen by electron microscopy – Detection of viral RNA / antigen ```
84
describe norovirus
• Mostly vomiting, (‘Winter vomiting disease’) • All ages • Outbreaks in community, institutions, hospitals & Food associated outbreaks • Incubation 1-2 days • Duration 2 days - diagnosis: PCR
85
what are the symptoms of meningitis
* Fever * Stiff neck * Photophobia * Headache * Vomiting * Irritable * Drowsy
86
what are the causes of bacterial viral and fungal meningitis
``` Bacteria: - Neisseria meningitidis - Haemophilus influenzae type b - Streptococcus pneumoniae (NHS to remember) ``` Viral: - enteroviruses (most common) & others Fungal: - e.g Cryptococcus neoformans
87
describe Neisseria meningitidis aka meningococcus
* Commonest and severe * Children (<5y) and young adults (15-20y) - rash • Capsule types A B & C and others Y & W – Vaccines for ACWY – Most UK cases now B – new vaccine has been introduced Present with: - Haemorragic rash - Purpura - Non blanching on tumbler test * Onset is sudden- hemorrhagic skin rash is a key clinical observation * Person to person via respiratory droplets
88
describe Pnemococcal meningitis
caused by Streptococcus pneumoniae aka pneumococcus more common in: – Older age /Post head trauma / Related to sinus etc – Splenectomy • Prevention: vaccines
89
describe Haemophilus meningitis
caused by Haemophilus influenzae (capsule type B) – Children 1-5 years of age – Rare now since the HIB vaccine Prevention: • prophylaxis for close contacts • Hib vaccine (UK childhood immunization schedule)
90
what causes TB meningitis
M. tuberculosis
91
describe neonatal meningitis
* Causes : Group B haemolytic streptococci (GBS) -10-30% of pregnant women colonized- (normal inhabitants of female genital tract) * Also E. coli & L. monocytogenes * Early or later onset disease. <1wk or >1wk age * Permanent neurological sequelae- cerebral or cranial nerve palsy, mental retardation, hydrocephalus * Clinical diagnosis -no specific signs-difficult to diagnose * Blind' antibiotic treatment
92
describe fungal meningitis
• C. neoformans encapsulated yeasts • Associated with meningitis in patients with depressed cell-mediated immunity (AIDS) • Slow onset • Diagnosis: India-ink-stained preparations of CSF- antigen detection • Treatment: antifungal drugs
93
what are the general principals for bacterial meningitis
- antibiotics - give first does before urgent transfer to hospital - if meningococcal disease - benzyl penicillin IV or IM - if you don't know the cause of the bacterial meningitis - cefotaxime or ceftriaxone
94
what is encephalitis, what is the main cause and how is it treated what are the main symptoms
* Inflamation of the brain substance * -Key cause herpes simplex (HSV-1) – temporal lobe brain * Treat with aciclovir – early – high dose – IV – Stroke like signs and memory loss – Behavioural changes – Reduced consciousness – Seizures
95
what are prions
``` strange infectious agents • Tiny – much smaller than viruses • No nucleic acid! • resistance to heat, disinfection and UV radiation • Very long incubation period • No immune response ```
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describe transmissible Spongiform | encephalopathies
- transmitted by folding event - protein randomly folds to wrong shape - this wrong shape one causes other normal proteins to now change to the wrong shape version (autocatalytic) - can have a genetic predisposition to it - infectious from person to person ``` presentation: • Dementia • Ataxia • Other features • Progressive & fatal - brain full of holes - no actual inflammation ``` examples Is CJD Creutzfeldt-Jakob disease
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define bacteruria
Bacteriuria: the presence of bacteria in the urine
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define pyuria
Pyuria: the presence of white blood cells in the urine
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Name the common bacterial causes of community-acquired and nosocomial UTI
1 = Escherichia coli (70-95% of community acquired UTI) - Escherichia coli with a P-fimbriae attach to urological epithelium Allows them to ascend the renal tract to cause pyelonephritis (kidney infection) Gram negative organisms: Members of the Enterobacteriacae: - Klebsiella spp.  - Enterobacter spp.  - Proteus spp.  - Morganella spp.  and others Pseudomonas aeruginosa Important Gram positive organisms: Staphylococcus saprophyticus Streptococcus agalactiae (Group B Streptococcus) Enterococcus faecalis/faecium