Infectious Disease Flashcards
What are bacteria?
- Single celled organisms
- Some pathogenic + cause disease
- Anaerobic (don’t need O2) or aerobic (do)
What are gram positive bacteria?
- Thick peptidoglycan wall
- Stains with crystal violet stain
What are gram negative bacteria?
- No peptidoglycan cell wall
- Doesn’t stain with crystal violet stain but will with others
- Counterstain-> binds to cell membrane so turns pink/red
What are atypical bacteria?
Not stained or cultured in the normal way (eg crystal violet or other stains)
What is the anatomy of bacteria?
- Cell wall
- Outer membrane
- Nucleic acid-> DNA
- Ribosomes-> where proteins synthesised
- Folic acid-> needed for synthesising + regulating DNA
Why do bacteria need folic acid?
needed for synthesising + regulating DNA
What are examples of gram positive cocci?
Staph, strep, enterococcus
What are examples of gram positive rods?
- Corneybacteria
- Mycobacteria
- Listeria
- Bacillus
- Nocardia
What are examples of gram +ve anaerobes?
- Clostridium
- Lactobacillus
- Acintomyces
- Propionibacterium
What are examples of gram negative bacteria?
- Neisseria meningitidis
- Neisseria gonorrhoea
- H/influenzae
- E.coli
- Klebsiella
- Pseudomonas aeruginosa
What are examples of atypical bacteria?
Leigonella, psittaci, mycoplasma pneumoniae, chlamydydophilia pneumoniae, Coxiella burnetti
What is MRSA?
- Methicillin-resistant staph aureus
- Resists beta-lactams-> penicillins, cephalosporins, carbapenems,
- Colonised on skin + resp tract
How is MRSA prevented?
- Screen via nasal + groin swabs on admission for surgery/treatment
- Chlorhexidine washes + antibacterial nasal creams
How can MRSA be treated?
Doxycycline, clindamycin, vancomycin, linezolid, teicoplanin
What are ESBLs?
- Extended Spectrum Beta-Lactamase bacteria
- Resistant to beta-lactams-> produce beta-lactamase and destroy
- Often E.coli + Klebsiella
What infections do ESBLs often cause?
E.coli + Klebsiella-> UTIs + pneumonia
How can ESBL infection be treated?
Carbapenems-> eg meropenem
How do bacteriostatic antibiotics work?
Stop bacterial reproduction + growth
How do bacteriacidal antibiotics work?
Kill bacteria directly
How does penicillin work?
Inhibits cell wall synthesis + has beta-lactam ring
How do carbapenems work?
Inhibits cell wall synthesis + has beta-lactam ring
How do cephalosporins work?
Inhibits cell wall synthesis + has beta-lactam ring
How does vancomycin work?
Inhibits cell wall synthesis + doesn’t have beta-lactam ring
How does teicoplanin work?
Inhibits cell wall synthesis + doesn’t have beta-lactam ring
How does trimethoprim work?
Inhibits folic acid metabolism
How do macrolides (eg clarythromycin) work?
Inhibit protein synthesis by targetting ribosomes
How does clindamycin work?
Inhibit protein synthesis by targetting ribosomes
How do tetracyclines (eg doxycycline) work?
Inhibit protein synthesis by targetting ribosomes
How does gentamicin work?
Inhibit protein synthesis by targetting ribosomes
How does chloramphenicol work?
Inhibit protein synthesis by targetting ribosomes
How does metronidazole work?
- Is reduced to active form in anaerobic cells then inhibits nucleic acid synthesis
- Effective against anaerobes
How many people with penicillin allergy also have cephalosporin + carbapenem allergy?
Around 1%
What is the treatment pathway for a hospital patient with infection?
- Start with amoxicillin-> strep, listeria, enterococcus
- Switch to co-amoxiclav-> staph, haemophilus, E.coli
- To tazocin-> pseudomonas
- To meropenem-> ESBLs
- Add teicoplanin/vancomycin-> MRSA
- Add clarithromycin or doxycycline-> atypicals
What is the pathophysiology of sepsis?
- Pathogen recognised by macrophages, lymphocytes + mast cells
- Release cytokines etc-> activate other systems + make endothelial BV lining more permeable
- Fluid into extracellular space-> oedema + less IV volume-> space between blood + tissues-> less O2 to tissues
- NO release-> vasodilation
- Coagulation activation-> fibrin circulating-> less tissue perfusion + platelets consumed to form clots-> DIC (thrombocytopaenia + haemorrhages)
- Hypoperfusion-> raised lactate (anaerobic resp)
- Disregulated immune response
What is sepsis?
Disregulated immune response to infection causing systemic inflammation
What is septic shock?
- Systolic BP <90 after fluid resus
- Lactate >4mmol/L (hypoperfused tissues)
- Circulatory, cell + maetabolic abnormalities
How is septic shock managed?
IV fluids, ICU, inotropes (noradrenaline- stimulate CV system)
What are the features of severe sepsis?
Hypoxia, oliguria, AKI, thrombocytopaenia, coagulation dysfunction, lactate >2mmol/L
What are the risk factors for developing sepsis?
- Age <1 or >75
- Chronic conditions
- Chemo, steroids, immunosuppressants
- Recent burns
- Pregnant or pregnant in last 6 weeks
- trauma or surgery in last 6 weeks
- Catheters + central lines
- IVDU
What infections commonly cause sepsis?
Pneumonia, UTI, abdominal, skin/soft tissue
What are the signs of sepsis?
- Tachypnoea often first
- Picked up on NEWS score
- Infection, non-blanching rash, reduced UO, mottled skin, cyanosis
- New onset AF
- Obs might be normal in neutropaenic or immunosuppressed patients
At what NEWS score should you be worried about sepsis?
Definitely 5+ but depends on patient
What are the red flag features of being at high risk for sepsis?
If 1+ should suspect…
- New onset or altered mental state
- Systolic BP <90 or >40 change
- HR >130
- RR >25
- SpO2 92% on oxygen
- Lactate >2
- AKI
- Recent chemo
- No PU in 18 hours
- Non blanching rash
- Mottled skin
What are the amber flag features of being at risk for sepsis?
Investigate + review within 1 hour if 2+ are present…
- Mental status concerns
- Systolic BP 91-100
- HR 91-130
- RR 21-24
- Immunosuppressed or recent trauma/surgery
- Acute deterioration of functional ability
When might lactate be falsely elevated?
Alcoholics, liver disease, adrenaline nebs
How is sepsis investigated?
- Bloods-> FBCs, U+Es, LFTs, CRP, clotting
- Blood culture
- Blood gas-> lactate
- Locate source-> urine dip + culture, CXR, CT abdomen, LP
How is sepsis managed?
- Sepsis 6 (BUFALO)-> blood culture, urine output, fluids, antibiotics (broad spec), lactate, oxygen
- IV crystalloids-> stat boluses but call critical care if oedema or 2L+ given
- Local guidelines for antibiotics-> co-amoxiclav in South Yorkshire
What is neutropaenic sepsis and what features might suggest it?
- Neutrophils <1 x 10^9/L
- Temperature 38+
What can cause neutropaenic sepsis?
- Chemo
- Clozapine
- Immunusuppressants eg methotrexate or infliximab
- -Carbimazole
- Quinine
How is neutropaenic sepsis treated?
Tazocin (piperallicin + tazobactam)
What are common causes of chest infections?
- Viral most common
- Strep pneumoniae (50%)
- H.influenzae (20%)
- Moraxella catarrhalis-> COPD
- P.aeruginosa-> CF, bronchiectasis
- S.aureus-> CF
- Atypicals eg leigonella
What antibiotics are usually used in chest infections?
- Amoxicillin
- Erythromycin
- Clarithromycin
- Doxycycline
What bacteria/pathogens usually cause UTIs?
- E.coli
- Klebsiella
- Enterococcus
- P.aeruginosa
- Candida albicans
What often causes bacteria/pathogens to enter the urethra and cause UTIs?
- Faeces-> intestinal bacteria
- Incontinence or hygiene issues
- Urinary catheters
How do lower UTIs present?
- Dysuria, frequency, urgency, incontinence
- Suprapubic pain/discomfort
- Cloudy/smelly urine
- Haematuria
- Confusion
How does pyelonephritis present?
- Fever, unwell, vomiting, loss of appetite
- Loin, suprapubic, back pain-> uni or bilateral
- Haematuria
- Renal angle tenderness
What are nitrites?
- Nitrates are a waste product of urine
- Are broken down by gram negative bacteria into nitrites
- Indicator of UTI
What does a urine dip result of +ve for nitrites and WBCs indicate?
Diagnostic of UTI
What does a urine dip result of +ve for nitrites only indicate?
Diagnostic of UTI
What does a urine dip result of +ve for WBCs only indicate?
Not UTI unless clinical evidence
Why might RBCs be present in urine?
UTI, nephritis, cancers
When is it important to include MSU (midstream urine sample for culture) in investigations for UTI?
Complicated UTI-> pregnancy, UTIs, atypical symptoms, when not improved with antibiotics
How is UTI managed (simple, in women)?
3 days of trimethoprim or nitrofurantoin or amoxicillin
How is UTI managed (men, pregnancy or catheter-associated)?
7 days of trimethoprim or nitrofurantoin or amoxicillin
How is UTI managed (immunosuppressed, abnormal anatomy, kidney issues)?
5-10 days of trimethoprim or nitrofurantoin or amoxicillin
When should nitrofurantoin be avoided?
eGFR <45
What risks do UTIs pose in pregnancy?
Pyelonephritis, PrOM, pre-term labour risks
How is UTI in pregnancy managed?
- 7 days antibiotics even if asymptomatic
- Nitrofurantoin-> NOT in 3rd trimester (haemolytic anaemia of newborn risk)
- Trimethoprim-> not in 1st trimester (anti-folate and neural tube defect risks)
When and why should trimethoprim be avoided in pregnancy?
in 1st trimester (anti-folate and neural tube defect risks)
When and why should nitrofurantoin be avoided in pregnancy?
in 3rd trimester (haemolytic anaemia of newborn risk)
How is pyelonephritis managed?
- 7-10 days of cefalexin, co-amoxiclav, trimethoprim or ciprofloxacin
- Investigate renal abscess or stones if doesn’t respond
What are the side effects of ciprofloxacin?
Tendon damage + lowers seizure threshold
How is chronic pyelonephritis investigated?
DMSA scan-> scarring/damage areas not taken up so obvious where
What bacteria causes cellulitis?
- Staph aureus
- Group A strep eg s.pyogenes
- Group C strep
- MRSA
What causes cellulitis?
- Infection of skin + soft tissue
- Skin trauma, eczema, fungal nail infection, ulcers-> point of entry where skin breaks
- Often staph aureus or group A strep
How does cellulitis present
Erythema, warm, tense, thickened, oedematous, bullae (fluid-filled blisters)
What causes impetigo?
Group A strep or staph aureus
What is the Eron classification for cellulitis?
Assesses severity…
- Class 1-> no systemic toxicity/comorbidity
- 2-> systemic toxicity/comorbs
- 3-> Significant systemic
- 4-> sepsis, life-threatening
What antibiotics are usually used in cellulitis?
- Flucloxacillin
- Clarithromycin
- Clindamycin
- Co-amoxiclav
What usually causes tonsillitis?
- Virus
- Group A strep eg s.pyogenes
What are ENT infections commonly caused by?
- Virus
- Group A strep eg s.pyogenes
- H.influenzae
- M.catarrhalis
- S.aureus
What are the Centor criteria for tonsillitis?
1 point for…
- Fever 38+
- Tonsillar exudates
- No cough
- Tender anterior cervical LNs
3+-> should give antibiotics
What is the feverPAIN score for tonsillitis?
- Fever
- Purulent tonsils
- Absence of cough/coryza
- Inflammation
- New symptoms (<3 days)
Consider delayed antibiotics if score 2/3 and consider immediate if 4+
What antibiotic is usually used in tonsillitis?
Penicillin V (phenoxymethylpenicillin) for 10 days
What are the symptoms of otitis media?
- Ear pain
- Bulging red tympanic membrane
- Discharge if perforates
How is otitis media managed?
- Usually resolves in 3-7 days by self
- Amoxicillin
- If doesn’t resolve in 2 days-> co-amoxiclav
How is sinusitis managed?
- Usually resolves in 2-3 weeks without treatment
- No antibiotics within <10 days
- No improvement-> 2 weeks high dose steroid nasal spray
- Still none-> penicillin V for 5 days, co-amoxiclav switch if none after 2 days
What bacteria usually cause intra-abdominal infections?
- Anaerobes-> bacteriodes, clostridium
- E.coli
- Klebsiella
- Enterococcus
- Strep
What bacteria is co-amoxiclav effective and not effective against?
Yes-> Gram +ve, gram -ve and anaerobic
No-> pseudomonas, atypical
What bacteria is ciprofloxacin (and other quinolones) effective and not effective against?
Yes-> gram +ve, gram -ve, atypicals
No-> anaerobes
What bacteria is metronidazole effective and not effective against?
Yes-> anaerobic
No-> aerobic
What bacteria is gentamicin effective and not effective against?
Yes-> gram -ve, some gram +ve (eg staph)
What bacteria is vancomycin effective and not effective against?
Yes-> gram +ve, MRSA, gram -ve (when + gentamicin), anaerobes (+ metronidazole)
What bacteria are cephalosporins effective and not effective against?
Yes-> gram +ve and gram -ve (broad spec)
No-> anaerobes
Risk of C.diff
What antibiotics are commonly associated with C.diff?
Cephalosporins
What bacteria is tazocin effective and not effective against?
Yes-> gram +ve, gram -ve, anaerobic, usually when unresponsive to other antibiotics
No-> atypical or MRSA
What bacteria is meropenem effective and not effective against?
Yes-> gram +ve, gram -ve, anaerobic, usually when unresponsive to other antibiotics
No-> atypical or MRSA
When does spontaneous bacterial peritonitis occur?
Liver failure
What is used to treat spontaneous bacterial peritonitis?
- Tazocin 1st line
- Cefotaxime
- Levofloxacin + metronidazole
What bacteria usually cause septic arthritis?
- S.aureus
- N.gonorrhoea-> gonococcal, when sexually active
- Group A strep
- H.influenza
- E.coli
What commonly causes septic arthritis?
Hip/knee replacement-> higher risk in revision surgery
What is the presentation of septic arthritis?
- Single joint-> often knee
- Hot, swollen, painful, limited ROM, systemic
What are the differentials for septic arthritis?
- Gout-> negatively birefringent urate crystals
- Pseudogout-> calcium pyrophosphate crystals, positive birefringent
- Reactive arthritis-> conjunctivitis or urethritis etc
- Haemoarthrosis
How is septic arthritis managed?
- Hot joint policy-> who admitted and which antibiotics
- Aspirate-> gram stain, crystal microscopy, culture & sensitivity
- Empirical IV antibiotics-> flucloxacillin + rifampicin 1st line
What is the influenza virus?
- RNA virus with 3 types-> A, B, C
- A type has H+N subtypes-> H1N1 (swine flu) etc
Who is eligible for free influenza vaccines?
65+, kids, pregnant, HC workers, chronic conditions (asthma, COPD, HF, DM)
How does influenza present?
Fever, coryzal symptoms. lethargy, fatigue, anorexia, loss of appetite, muscle aches, joint aches, headache, dry cough, sore throat
How is influenza diagnosed?
- Viral nasal or throat swabs for PCR
- Give public health data to monitor cases
How is influenza managed?
- Self care if low risk
- High risk-> oral oseltamivir for 5 days or inhaled zanamivir for 5 days
- PEP for high risk-> within 48 hours of close contact
What are the potential complications of influenza?
Otitis media, sinusitis, bronchitis, viral pneumonia, worsening of chronic conditions, febrile convulsions, encephalitis
What is gatroenteritis?
Inflammation of stomach + intestines causing nausea, vomiting and diarrhoea
What pathogens commonly cause gastroenteritis?
- Viruses-> rotavirus, norovirus, adenovirus
- Bacteria-> E.coli, campylobacter jejuni, Shigella, salmonella, bacillus cerus etc
- Parasites-> Giardiasis
How is E.coli gastroenteritis spread?
- Faeces, water, unwashed salad
- Normal intestinal bacteria + some strains cause GE
What is the pathophysiology of E.coli gastroenteritis?
E.coli 0157-> produces Shiga toxin
How does E.coli gastroenteritis present?
- Abdominal cramps, bloody diarrhoea, vomiting
- Risk of HUS-> destroys RBCs
How is E.coli gastroenteritis managed?
- Conservative
- Avoid antibiotics-> increased HUS risk
What is campylobacter jejuni?
- Gram negative curved/spiral bacteria
- Commonly causes traveller’s diarrhoea and bacterial gastroenteritis
How does campylobacter jejuni gastroenteritis spread?
Raw poultry, untreated water, unpasteurised milk
How does campylobacter jejuni gastroenteritis present?
- Abdominal cramps, diarrhoea, bloody stools, vomiting, fever
- Incubates for 2-5 days
- Resolves in 3-6 days
When are antibiotics used in campylobacter jejuni gastroenteritis?
- When organism isolated
- When severe or risk factors (HIV etc)
- Azithromycin or ciprofloxacin used
What is the pathophysiology of shigella gastroenteritis?
- Produces Shiga toxin-> can cause HUS
- Spread via faeces, swimming pools, food
How does shigella gastroenteritis present?
- Bloody diarrhoea, abdominal cramps, fever
- Incubates 1-2 days
- Resolves in 1 week
How is shigella gastroenteritis managed?
- Conservative
- Severe-> azithromycin or ciprofloxacin
How is salmonella spread?
Raw eggs, poultry, food contaminated with faeces
How does salmonella present?
- Watery diarrhoea, mucus, blood, abdominal pain, vomiting
- Incubation 12 hours-3 days
- Symptoms resolve in 1 week
How is salmonella managed?
Only give antibiotics when severe + guide by stool culture
What is bacillus cereus infection?
- Gram positive rod
- Spread through inadequately cooked food-> often rice
- Cerulide toxin produced-> watery diarrhoea in intestines
How does bacillus cereus gastroenteritis present?
- Abdominal cramping and vomiting-> wIthin 5 hours of ingestion
- Watery diarrhoea-> 8 hours after
- Resolves in 24 hours
What is yersinia enterocolitica infection?
- Gram negative bacillus
- Spread through contamination with urine/faeces or eating uncooked pork
How does yersinia enterocolitica infection present?
- Young kids
- Watery/bloody diarrhoea, abdominal pain, fever, lymphadenopathy
- Incubation-> 4-7 days
- Can last 3+ weeks
- Mesenteric lymphadenitis-> right sided abdo pain
How is staph aureus gastroenteritis spread?
- Dairy, eggs, meat
- Enterotoxins-> small intestine inflammation
How does staph aureus gastroenteritis present?
- Diarrhoea, vomiting, abdominal cramps, fever
- Within hours of digestion
- Lasts 12-24 hours
What is giardiasis?
- Gastroenteritis due to giardia lamblia parasite
- Lives in animals’ intestines-> release cysts in stools-> contaminate food + water-> infect host
- Faecal-oral
How does giardiasis present?
Chronic diarrhoea, no symptoms
How is giardiasis managed?
- Stool microscopy
- Metronizadole
How is gastroenteritis managed (generally)?
- Isolate + infection control
- Samples-> MC&S
- Fluid challenge, rehydration (dioralyte), IV fluids
- Stay off work/school for 48 hours until symptoms resolved
- Antidiarrheal in some types (eg loperamide)
- Antiemetics
- Antibiotics when high risk
How long should people stay off work/school when they have gastroenteritis?
48 hours after symptoms resolve
What complications can gastroenteritis have?
Lactose intolerance, IBS, reactive arthritis, GBS
What bacteria usually cause meningitis?
- Neisseria meningitidis (meningococcus)
- Group B strep-> neonates (from vagina during birth)
What is meningococcal septicaemia?
- Meningococcus in bloodstream
- Causes DIC-> non-blanching rash
How does meningitis present?
- fever, neck stiffness, vomiting, headache, photophobia, LOC, seizures
- non-blanching rash-> meningococcal septicaemia
- Neonates-> hypotonia, poor feeding, lethargy, hypothermia, bulging fontanelle
What is the criteria for getting a lumbar puncture in suspected meningitis?
- <1 month with fever
- 1-3 months with fever + unwell
- <1 year with unexplained fever + features of serious illness
What is Kernig’s test and what does it show?
- Patient on back + flex 1 hip and knee to 90 degrees
- Straighten knee + keep hip flexed 90 degrees
- Stretch meninges
- Spinal pain/resistance-> meningitis
How is meningitis managed initially in the community?
Urgent stat IM/IV benzylpenicillin-> different dose for different ages
How is meningitis managed in hospital?
- Blood culture + LP before antibiotics unless acutely unwell
- Local policy
- <3 months-> cefotaxime + amoxicillin
- > 3 months-> ceftriaxone
- Vancomycin-> when risk of pneumococcal (eg travel)
- Steroids-> dexamethasone for 4 days in >3 months to prevent hearing + neuro damage
- Inform PHE
What antibiotics are used in meningitis?
- In community-> Urgent stat IM/IV benzylpenicillin
- Local policy
- <3 months-> cefotaxime + amoxicillin
- > 3 months-> ceftriaxone
- Vancomycin-> when risk of pneumococcal (eg travel)
Why are steroids used in meningitis management?
prevent hearing + neuro damage
When and what is used for PEP in meningitis?
- Single dose ciprofloxacin
- Within 24 hours of pt diagnosis
- Risk when prolonged contact within 7 days of illness onset
- No symptoms after 7 days-> unlikely to have
How is viral meningitis managed?
- CSF sample + viral PCR from LP
- Acyclovir if HSV
What causes viral meningitis?
HSV, enterovirus, VZV
How is LP performed in meningitis?
- Into L3/4-> cord ends at L1/2
- Send-> bacterial culture, viral PCR, cell count, protein, glucose
- Blood glucose-> compare CSF
How does bacterial meningitis show on an LP?
- Cloudy
- High protein
- Low glucose
- High WCCS + neutrophils
- Positive culture
How does viral meningitis show on an LP?
- Clear
- Mildly raised or normal protein
- Normal glucose
- High WCC + lymphocytes
- Negative culture
What are some complications of meningitis?
Hearing loss, seizures, epilepsy, cognitive impairment, LD, memory loss, focal neuro (limb weakness + spasticity)
What is tuberculosis caused by?
Mycobacterium tuberculosis-> acid fast bacilli (unable to gram stain as resistant)
How is mycobacterium tuberculosis stained?
Zeihl-Neelsen stain-> red on blue background
Who is tuberculosis more prevalent in?
- Non-UK born patients
- Immunocompromised
- Close contacts from high prevalence areas
- Homeless
- Drug users
- Alcoholics
What is the disease course of tuberculosis?
- Spread by inhaling saliva droplets
- Into lymphatics + blood-> granulomas
- Active-> can kill + clear
- Latent-> encapsulated + progress stopped
- Secondary-> reactivation of latent
- Miliary-> immune system can’t control so disseminates
- Extrapulmonary-> LNs, pleura, CNS, pericardium, GI, GU, bones, skin
Why is tuberculosis hard to treat?
- Slowly divides
- High oxygen demand
- Hard to culture
- Can become latent
How does the BCG vaccine work?
- Live-attenuated
- Intradermal
- Need negative Mantoux test + immunosuppression tests before-> due to live vaccine risks
Who gets the BCG vaccine?
- Neonates in high risk areas or relatives from
- FH
- Unvaccinated with close contacts
- HC workers
How does tuberculosis present?
- Chronic + gradually worsening
- Cough, haemoptysis, LNopathy
- Lethargy, fevers, night sweats, weight loss, erythema nodosum
- Spinal pain-> Pott’s disease of the spine
How is tuberculosis investigated?
- Ziehl-Neeslen stain
- Mantoux test
- Interferon-gamma release assays (IGRAs)-> when +ve Mantoux test
- CXR-> primary, reactivated and miliary have different signs
- Sputum culture-> eg from bronchoscopy
- Blood cultures
- LN aspiration/biopsy
- Nucleic acid amplification test-> when high risk
How does the Mantoux test work?
- Inject intradermally
- Bleb under skin
- Back in 72 hours
- +ve if >5mm
What CXR findings might be present in tuberculosis?
- Primary-> patchy consolidation, effusions, hilar LNopathy
- Reactivated-> patchy/nodular consolidation, cavitation
- Milary-> ‘millet seeds’
How is active tuberculosis managed?
- Rifampicin-> 6 months
- Isoniazid-> 6 months
- Pyrazinamide-> 2 months
- Ethambutol-> 2 months
- Also notify PHE, isolate for 2 weeks, test for HIV etc
What are the side effects of the tuberculosis drugs?
- Rifampicin-> red/orange urine/tears, hepatotoxicity
- Isoniazid-> peripheral neuropathy, hepatotoxicity
- Pyrazinamide-> hyperuricaemia, gout, hepatotoxicity
- Ethambutol-> colour blind + reduce acuity
What is the pathyphysiology of Human Immunodeficiency Virus?
- HIV-> RNA retrovirus, types 1 (most) + 2
- Enters + destroys CD4 T-helper cells
- Transmitted by sex, vertical (mum to baby), mucous membranes + open wounds (eg needles)
How does Human Immunodeficiency Virus progress?
- Seroconversion illness-> flu like, within a few weeks of infection
- Asymptomatic
- Progresses-> immunocompromised + AIDS-defining illnesses
How does screening for Human Immunodeficiency Virus worK?
- Antibody test, HIV antigen (P24), PCR (HIV RNA + viral load)
- Everyone in hospital or with RFs in community
- Need consent
- Antibodies can be -ve for 3 months after exposure-> repeat
How is Human Immunodeficiency Virus monitored?
- Viral load-> copies per ml of bleed, 50-100/ml counts as undetectable
- CD4 count-> 500-1200cells/mm3 normal, <200 is AIDS
What are AIDS-defining illnesses?
- Kaposi’s sarcoma
- CMV
- Pneumocystis jivorecii pneumonia
- Candidiasis of oesophagus/bronchi
- Lymphomas
- TB
How is Human Immunodeficiency Virus managed?
- Antiretrovirals-> 2 nucleotide reverse transcriptase inhibitors (NRTIs) + 1 other agent
- Eg-> tenofovir + emtricitabine + protease inhibitor
- Aims-> normal CD4 + undetectable viral load
- Tailored on bloods but all get treatment-Other-> co-trimoxazole (PCP prevention), cervical smears (HPV risk), vaccines (eg annual flu)
- Newborn with HIV +ve mum-> ART for 4 weeks after birth
- Contraception-> condoms + dams, risks with unprotected even with undetectable load
- Can conceive-> IVF, sperm washing etc
What is PEP for Human Immunodeficiency Virus?
- Use in <72 hours of exposure
- ART combo-> tenofovir + emtricitabine + reltegravir for 28 days
- Test 3 months after
What causes malaria?
- Plasmodium-> protozoan parasites eg falciparum, vivax, ovale
- Female anopheles mosquito-> bite
- Spores injected when bite human-> mature in liver to merozoites-> infect RBCs in blood-> reproduce in 48 hours-> RBCs rupture + release merozoites to blood-> haemolytic anaemia + high spiking fevers every 48 hours
- Can be dormant for years in vivax + ovale
How does malaria present?
- Incubation 1-4 weeks
- Fever, sweats, malaise, myalgia, headache, vomiting
- Pallor, hepatosplenomegaly, jaundice
How is malaria diagnosed?
- Blood film-> parasites
- 3 samples over 3 days-> 48 hour cycle of release
How is malaria managed?
- Admission in falciparum-> can deteriorate
- Doxycycline, quinine, riamet, malarone
- IV if severe-> quinine, artesunate
What are the complications of falciparum malaria?
Cerebral malaria, seizures, LOC, AKI, pulmonary oedema, DIC, severe haemolytic anaemia, multi-organ failure
What is used for malaria prophylaxis?
- High risk locations-> on BNF
- Sprays + nets
- Doxycycline-> 2 days before, during, 4 weeks after-> beware on sunlight
- Malarone or mefloquine
What antibiotics are associated with the development of Clostridium difficile infection?
Clindamycin, ciprofloxacin, cephalosporins
