Infectious Disease Flashcards
HIV
- Pathophysiology/Diagnosis
- Presentation
- Complications (including AIDS defining illnesses)
- Investigation
- Management
Pathophysiology/Diagnosis
HIV = RNA retrovirus
RF: other STIs, IVDU, unsafe blood transfusion/transplantation/piercing, needlestick injuries
Diagnosis
- HIV antibodies - most develop at 4-6/52 and 99% by 3/12 (so do 2x tests if 1st negative)
- p24 antigen (+ve from 1-4/52 post-infection)
(we do combined tests w/ both the above in the diagnose + screen. If +ve then repeat to confirm diagnosis. Testing should be at least 4/52 post-infection in asymptomatic patients + repeat at 12/52 if inital test -ve).
Presentation
Seroconversion. 3-12/52 post infection
- Sore throat, lymphadenopathy, malaise, myalgia, arthralgia, diarrhoea, macculopapular rash, mouth ulcers, rarely meningoencephalitis
Later:
Weight loss
Chronic diarrhoea:
- HIV enteritis
- crypotosporidium (protozoa + most common cause of diarrhoea in HIV. Red cysts on modified Ziehl Nielson of the stool. Managed supportively)
- CMV
- mycobacterium avium intracellulare
- giardia
Night sweats
Skin problems
Recurrent atypical infections e.g.
- TB
- mycobacterium avium intracellulare (seen when CD <50 - fever, sweats, abdo pain, diarrhoea, hepatomegaly, deranged LFTs, diagnosed w/ cultures + bone marrow examination)
- Pneumocystis jirovecci (fungal). All pateitns w/ CD3 <200 should have prophylaxis. Features: SOB, dry cough, v few chest signs. Pneumothorax common. Also hepatosplenomegaly, lymphadenopaty, choroid lesions. CXR: B/L infiltrates. Broncheolar lavage often needed for diagnosis. Managed w/ co-trimoxazole.
- Serious life threatening illnesses
Complications
AIDS if CD4 <200 OR certain opportunistic infections:
- Kaposi’s sarcoma (HHV-8, purple papules or plaques on skin or mucosa +/- ulceration. Lung involvement -> haemoptysis/pulmonary effusion. Mx: radiotherapy + resection
- Pneumocystic jirovecci
- Chronic crytosporidium
- HIV related encephalopathy
- Mycobaterium Tuberculosis
- Invasive Cervical Cancer
Investigation
Above
Management
- Antiretroviral therapy (typically at least 3 drugs)
- e.g. maraviroc, zidovudine, abacavir, nevirpaine, indinavir, raltegravir
Give the % transmission risk from needlestick injuries and the PEP for the following
- Hepatitis A
- Hepatitis B
- Hepatitis C
- HIV
Hepatitis A
-PEP: human normal immunoglobulin OR Hep A vaccine
**Hepatitis B **
- Transmission rate: 30%
- HBsAg +ve source: booster dose of vaccine (if known non-responder then HBIG and booster)
Hepatitis C
- Transmission rate: 0.5-2%
- monthly PCR - if seroconversion then interferon +/- ribavirin
HIV
- Transmission rate: 0.3%
- PEP: combination of PO antiretrovirals (tenofovir, lopinavir, ritonavir, emtricitabine) ASAP (within 1-2h but can be started up to 72h post-exposure + continue for 4/52)
- Serological testing at 12/52 following completetion of PEP
- reduces transmission by 80%
Clostridium Infection. How do the folloing present?
- Clostridium Perfringens
- Clostridium Botulinum
- Clodstridium Difficle
- Clostridium Tetani
Clostridium Perfringens –> gas gangrene + haemolysis (type 2 necrotising fascitis)
- Features: tender oedematous skin w/ haemorrhagic blebs + bullae +/- crepitus on palpitation
- IV abx + surgical debridement
C. Botulinum
- Prevents ACh release –> flaccid paralysis
- Typically seen in canned food/honey
- Antitoxin should be given asap. If severe may need mechanical ventilation. Abx not required.
C.Diff
- Diarrhoea +/- blood), pseudomembranous colitis, abdo pain, raised WCC, toxic megaolon
- Mx: PO vanc (or fidoxamicin if 2nd episode within 12/52). If severe: PO vanc and IV metro
C. Tetni
- Spastic paralysis
- lock jaw, facial grimacing, spasms, back + neck stiffness, dysphagia, restlessness
- Reflex spasms triggered by minor external stimuli e.g. noise, light, touch
- Normal vaccination: 2,3,4 months; 3-5 years, 13-18year (5 in total = long-term protection)
- Managing wounds:
*Clean wound * = no prophylaxis needed
*Tetnus prone wound * = puncture in contaminated environment, wound w/ FB, compound #, wound/burn w/ systemic sepsis, some animal bites
High risk tetanus: heavy contamination (soil, manure), wound/burns w/ extensive devitalised tissue, wound/burns needing surgical intervention
- Management
- If full course of tetanus w/ last dose <10y ago = no action
- If full course w/ last dose >10y OR incomplete OR unknown vaccine status = Reinforcing dose of vaccine for tetanus prone wound AND cavvine plus tetnus immunoglobulin for high-risk wound
Which vaccines are live-attenuated? When can they not be given?
Live Attenuated
MY BOOTII
- MMR
- Yellow Fever
- BCG
- Oral polio
- Oral rotavirus
- Typhoid
- Intranasal Influenza
Inactivated: rabies, hep A, influenza (IM), tetnus, diphtheria, pertussis
Live attenuated vaccines should be avoided in those who are immunocompromised e.g. on azathioprine
Typhoid and Paratyphoid
- Causative organism
- Presentation
- Investigation
- Management
Causative Organism
- Salmonella Typhi and Salmonella Paratyphi (aerobic, gram -ve rods, NOT normal gut commensals)
Presentation
- Initial systemic upset: headache, fever, artralgia
- Relative bradycardia
- Abdo pain, distension
- Constipation (N.B. altho salmonella can cause diarroea, typhi typically causes constipation)
- Rose spots: present on trunk in 40% (more common in paratyphoid)
Complications: OM (esp in sickle cell), GI bleed/perforation, meningitis, cholecystitis, chronic carriage
Investigation
- Blood or stool sample
- OR bone marrow sampling (altho this is not first line due to pain)
Management
- Prompt abx: ciprofloxacin or azithromycin
Traveller’s Diarrhoea
Common causes + their presentation
- E.coli = most common
- Watery stools, abdo cramps nausea - Campylobacter (most common bacterial infectious gastroenteritis in UK)
- Cause: campylobacteri jejuni
- Incubation: 1-6d
- Features: prodrome of headache + malaise; Bloody diarrhoea; Abdo Pain (can mimic appendicitis)
- Mx: normally self-limiting but if severe, immunocompromised or symptoms >1/52 then PO clarithromycin
- Complications: Guillain-Barre, reactive arthritis, sepsis, endocarditis, arthritis - Shigella
- Bloody diarrhoea
- vomiting + abdo pain
Other
- Cholera
Profuse watery diarrhoea, severe dehydration, weight loss, not common amongst travellers
- Staph aurerus
Short incubation, severe vomiting (less diarrhoea) - Bacilleus Cereus
Short duration vomiting within 6h, then diarrhoea after 6h, associated w/ rice - Amoebiasis
Gradual onset bloody diarrhoea, abdo pain, tenderness, can last several weeks, >7d incubation - Giardiasis (protozoa = Giardia Lamblia)
RF: foreign travel, swimming, contaminated water, MSM
Pres: can be asymptomatic. OR non-bloody diarrhoea, steatorrhoea, bloating, abdo pain, lethargy, flatulence, weight loss, malabosrption + lactose intolerance
Ix: stool microscopy for trophozoite + cysts; stool antigen detection assay
Treatment: metronidazole
Meningitis
- Pathophysiology/Causative organisms
- Presentation
- Investigation
- Management
Pathophysiology
- Neonatal -3/12 = Group B strep
- 3/12 to 6years - N.meningitidis, Strep pneumoniae, H.influenzae
- >6y = N.meningitides, Strep pneumoniae
Presentation
- Neck stiffness, photophobia, headache
- Fever
- Gen unwell
- Purpuric non-blanching rash (sepsis)
- Signs: Kernig’s (pain on passive knee extension w/ hip flexed) + Brudzinski’s (pain on neck flex w/ hips flexed)
Investigation
- LP
Bacterial:cloudy, low glucose, high protein, polymorphs
Viral: clear, normal glucose, normal/raised protein, lymphocytes
TB: slight cloud, fibrin web, low glucose, high protein, lymphocytes
(so low glucose + high protein = bacterial and lymphoctes = TB
- Blood cultures
- PCR for meningococcus
- Contraindications to LP - bulging fontanelles, papilledema, focal neurology, DIC, cerebral herniation, meningococcal sepsis/rash, siezures, GCS <12
Management
Antibiotics
Community - IM benzylpenicillin
<3m = IV amoxicillin and IV cefotaxime
>3m -50y = IV cefotaxime (or ceftriaxone)
>50y = IV cefotaxime AND amoxicillin
N.B. most causes follow the above. If meningitis caused by listeria though = IV amoxcillin and Gentamicin
Steroids
<3m = no steroids
>3m = Dexamethasone if purulent CSF, WCC >1000 + raised protein, bacteria on gram stain
- adults - consider esp if suspected pneumococcal meningitis or raised ICP (>15 = raised). Start w/ first dose of abx + no later than 12h.
(N.B. contraindicated in sepsis or immunocompromise)
Other
- Public health notification
- Abx prophylaxis for any close contacts within the last 7 days (ciprofloxacin - single dose) + offer vaccine once serotype results available
Vaccination
- Men B - 8 + 16w then again at 1 year
- Men C - at one year
- Men ACWY - 14 years old and then up to age 25 if not previously had vaccine containing Men C
Encephalitis
- Pathophysiology
- Presentation
- Investigation
- Management
Pathophysiology
- 95% = HSV-1
- Typically affects temporal + inferior lobes
Presentation
- Fever, headache, psych sx, seizures, vomiting, ataxia, aphasia
Investigation
- CXR - raised protein + lymphocytes. PCR for HSV, VZV + enteroviruses.
- MRI - temporal + inferior lobe changes (petechial haemorrhages) (altho normal in 1/3rd)
- EEG - lateraised periodic discharge at 2Hz
Management
- IV aciclovir
Describe the presentation of Measles, Mumps and Rubella. How are they managed? What is the vaccination programme?
Measles
- Prodrome: conjunctivitis, fever, irritable
- Koplik spots (typically start pre-rash)
- Rash (starts behind ears + blotchy –> spreads + becomes confluent –> then desquamation of palms/soles)
- Complications: otitis media (most common), pneumonia, encephalitis, febrile convulsions, keratoconjunctivitis, subacute sclerosing panencephalitis (v rare, years after initial illness)
- Ix = IgM antibdoies
- Mx - supportive, notificable
Mumps
- Fever, malaise, muscular pain, parotitis (uni –> bilateral)
- Complications: Mumps orchitis, hearing loss (normally transient + unilateral), meningoencephalitis, pancreatitis)
- Mx - rest, paracetamol, notifiable
Rubella 9aka German Measles)
- Prodrome: low-grade fever
- Rash (maculopapular, face then to whole body)
- Lymphadenopathy (suboccipital)
- Complications: arthritis, thrombocytopenia, encephalitis, myocarditis
- In pregnancy: higher risk in early preg, after 16/52 damage is rare. Can -> sensorineural deafness, cataracts, PDA, growth retardation, hepatosplenomegaly
- Dx - IgM antibodies (N.B. it is difficult to distinguish from parovovirus clinically so check this as well as this also carries a risk to foetus)
- Mx in preg - discuss w/ local health protection unit. Non-immune mothers should be told to stay away from anyone w/ rubella + offered vaccination in post-natal period
Vaccination
- 12-15months and 3-5years
- CI: immunosupression, other live vaccine within last 4/52, allergy to neomycin, avoid pregnancy for 1/12, any immunoglobulin therapy within past 3/12
What are the following? How do they present/how are they managed?
- Cat Scratch Disease
- Leptospirosis
- Listeria
- Toxoplasmosis
Cat Scratch Disease
- Bartonella henselae
- Features: hx of cat scratch, regional lymphadenopathy, headache, malaise
- Mostly self-limiting
Leptospirosis
- Bacterial infection from contact w/ rat urine
- Early: mild flu-like illness, fever, subconjunctival haemorrhage
- Later –> AKI, hepatitis, aseptic meningitis
- Ix: serology, PCR, culture (blood, CSF, urine)
- Mx: high dose benpen or doxycycline
Listeria
- Bacteria. From unpasteurised dairy products.
- Features: diarrhoea, flu-like illness, CNS (meningoencephalitis, ataxia, seizures)
- In pregnancy –> miscarriage, prem labour, stillbirth, chorioamnionitis
- Ix: cultures, CSF
- Mx: Amoxicillin. Meningitis = amoxicillin and gentamicin
Toxoplasmosis
- Toxoplasma gondii (protozoa)
- In immunocompetent = most asymptomatic. If Sx -> self-limiting (mono like illness). Serology to diagnose. No treatment.
- In HIV/immunocompromised –> Cerebral lesions+ chorioretinitis. Mx: pyrimethamine + sulphadiazine for 6/52
- Congenital toxoplasmosis –> cerebral calcification, hydrocephalus, chorioretinitis, cataracts
What are the following?
- Diphtheria
- Cutaneous Larva Migrans
- Strongyloides Stercoralis
Diptheria
- Corynebacterium Diptheriae. Eastern Europe/ Russia/ Asia.
- Pres: ‘diptheric’ grey membrane on tonsils, sore throat, bulky cervical lymphadenopathy (-> bull neck), neuritis, heart block
- Ix: throat swab
- Mx: IM penicillin and diptheria antitoxin
Cutaneous Larva Migrans
- Infection w/ dog hookworm ancyclostoma braziliense
- ->intensely itchy, ‘creeping’ serpent like rash
- Mx w/ albendazole or ivermectin
Strongyloides Stercoralis
- Human parasitic nematode worm
- –> diarrhoea, abdo pain, bloating, papulovesicular lesions where skin penetrated (soles of feet, buttock), pruritic linear urticarial rash.
- Tx: ivermectin or albendazole
Malaria
- Pathophysiology
- Presentation
- Investigation
- Prophylaxis
- Management
Pathophysiology
- Protozoa
- Plasmodium falciparum = most common + dangerous
- Other: vivax, ovale, malariae
Presentation
- Headache, fever, splenomegaly, jaundice
- Cyclical fever - spikes every 48-72h
- Complications (falciparum) -> cerebral malaria, seizures, reduced GCD, AKI, pulm oedema, DIC, haemolytic anaemia, organ failure, death
Investigation
- Thick blood films (3 samples sent over 3 days to exclude)
Prophylaxis
- In pregnancy: chloroquine (taken once a week) (contraindicated in epilepsy)
- Children - DEET (>2/12 old); dozycycline if >12yo
- Other: Malarone (take for 7d after travel; all others need to be taken for 4/52), Doxycycline, Mefloquine (talen weekly, can be CI in epilepsy)
Management
- All w/ falciparum need admitting due to risk of deterioration
- Disease w/ ID for management. Options if severe = IV artesunate or quinine. If less severe PO artemesim or cholorquine.
- Management of animal and human bites
- Rabies (features + management)
Animal and Human Bites
- Cleanse wound. puncture type wounds should not be sutured.
- If draws blood OR if doesn’t draw blood but in high risk area (hands, feet, joints, face, genitals) then give co-amox
Rabies
- RNA virus. Dogs/bat/racoon/skunk. Affects CNS.
- Pres: prodrome: headache, fever, agitation. Hydrophobia. Hypersalivation. Negri bodies seen in infected neurones
- Mx: wash wound. If pt immunised give further 2x doses. If not immunised give HRIG + full course of vaccines.
- Which bacteria are patients at risk of post-splenectomy? How is this risk managed?
- If patients are found to be MRSA +ve how is this managed?
Splenectomy
- Encapsulated bacteria: SHiN SKiS. Step Pneumoniae; H.influenzae; Neisseria meningitides, group B Strep, Klebsiella, Salmonella typhi.
- Vaccines (preferrably give 2/52 pre-op if elective or have to wait at least 2/52 post-op if emergency): pneumococcal, HiB, meningococcal, annual influenza
- Prophylactic abx: Phenoxymethylpenicillin
MRSA
- All inpatients tested. Nasal + Skin swabs.
- If carrier: mupriocin nasal cream (TDS)+ chlorhexidine bodyy wash OD for 5d
- If active infection: vancomycin, teicoplaning, linezolid
Lyme Disease
- Pathophysiology
- Presentation
- Investigation
- Management
Pathophysiology
- Tick Bite. Borrelia Burgdorferi.
Presentation
Early (within 30d)
- Erythema migrans (bulls eye rash at site of bite)
- Systemic: headache, lethargy, fever, arthralgia
Late (after 30d)
- Cardio: heart block, peri/myocarditis
- Neuro: facial nerve palsy, radiculopathy, meningitis
Investigation
-clinical diagnosis if erythema migrans present
- ELISA/serology if not. Do within 4/52 of sx onset AND repeast in 4-6/52 if intiial test -ve bu still suspected.
Management
- remove tick w/ tweezers + wash the area
- If early Lyme –> doxycycline
- Late Lyme -> ceftriaxone
Which antibiotics are used in the following infections?
- COPD
- CAP
- Atypical pneumonia
- HAP
- UTI
- Acute pyelonephritis
- Acute prostatitis
- Impetigo
- Cellulitis
- Eryspelas
- Animal/Human bite
- Mastitis
- Strep A throat
- Sinusitis
- Otitis Media
- Otitis Externa
- Peridontal abscess
- Gingivitis
- Gonorrhoea
- Chlamydia
- PID
- Syphilis
- BV
- C.diff
- Campylobacter enteritis
- Salmonella (non typhoid)
- Shigellosis
- COPD = amoxicillin, tetracycline or clarithromycin
- CAP = amoxicillin
- Atypical pneumoniae = Clarithromycin
- HAP = within 5d of admission = co-amox. After 5d = tazocin
- UTI = nitro or trim (nitro, cefalexin or amoxicillin in preg)
- Pyelonephritis - Broad sepc cephalosporin or quinolone
- Prostatitis - quinolone, trimethoprim
- Impetigo - topical hydrogen peroxide (or PO fluclox if widespread)
- Cellulitis - fluclox (or co-amox if near eyes/nose)
- Erysipelas (fluclox)
- Bite = co-amox
- Mastitis = co-amox
- Strep A throat: phenoxymethylpenicillin
- Sinusitis: phenoxymethylpenicillin
- Otitis media: amoxcillin
- Otitis externa: fluclox
- Peridontal: amoxicillin
- Gingivitis: metronidazole
- Gonorrhoea: IM ceftriaxone
- Chlamydia: doxy or azithromycin
- PID: oflaxacin + metro OR IM cef + doxy + metro
- Syphilis: benpen or doxy
- BV: metro
- C. Diff: po vanc (or PO fidaxomicin or IV metro + PO vanc)
- Campylobacter: clarithromycin
- Salmonella: cipro
- Shigellosis: cipro
Discitis + Epidural Abscess
- Pathophysiology
- Presentation
- Investigation
- Management
Pathophysiology
- Most = staph aureus (normally haem spread from other source)
- Can also be: viral, TB, aseptic
Presentation
- Back pain
- Fever, rigors, sepsis
- Neuro: changing lower limb neuro = Epidural abscess has developed
Investigation
- Whole spine MRI (can be skip lesions)
- Blood cultures - to guide abx
- ? source - TOE, CXR, urine culture, dental x-rays
- Bloods + HIV, HepB/C + pre-op blood tests
Management
- Abx depends on source/causative organism
- If spinal epidural abscess develops patient wil need long-term course off abx +/- surgical evacuation
What might the following patterns of fever suggest?
- Continuous (remains high)
- Intermittent (spikes of temp, later returning to normal)
- Pel Ebstein Fever(cyclic fevers that rise and fall every few weeks)
- Daily Spikes
- Twice Daily Spikes
Continuous = viral pneumonia
Intermittent
- Quotidian (bouts of fever occuring within each 24h) - plasmodium knowlesi
- Tertian (every 2 days) - plasmodium vivax + ovale
- Quartan (every 3d) - plasmodium malariae
- Other: TB, sepsis, Lyme disease, EBV
Pel-Ebstein - Hodgkin’s lymphoma
Daily Spikes
- Abscess, TB, schisosomiasis
Twice Daily Spikes
- Leischmaniasis
Features of the following resp pathogens
- Resp Syncytial Virus
- Parainfluenza Virus
- Rhinovirus
- Influenza Virus
- Strep Pneumoniae
- H. Influenzae
- Staph aureus
- Mycoplasma pneuoniae
- Legionella pneumophilia
- Pneumoystic jiroveci
- Mycobacterium tuberculosis
- Resp syncytial virus - bronchiolitis
- Parainfluenza virus - croup
- Rhinovirus - Common cold
- Influenza Virus - Flu
- Strep pneumoniae - CAP
- H. Influenzae - CAP. Most common cause bronchiectasis/COCP exac. Causes Acute epiglottitis
- Staph aureus - pneumoniae, esp following influenza
- Mycoplasma pneumoniae - Flu like symptoms preceding dry cough. Complications: haemolytic anaemia, erythema multiforme
- Legionella pneumophilia - Air conditioning. Dry cough. Lymphopenia, deranged LFTs, hyponatraemia
- Pneumocystic jiroveci - pneumonia in HIV patients. Few chest signs. Exertional SOB/desat
- Mycobacterium tuberculosis -cough, night sweats, haemoptysis, upper lobe cavitation
Infectious Mononucleosis
- Pathophysiology
- Presentation
- Investigation
- Management
Pathophysiology (aka glandular fever)
- EBV (aka Human Herpes Virus 4)
- mostly young adults
Presentation
- Triad: sore throat, pyrexia, lymphadenopathy
- Palatal petechiae
- Malaise, anorexia, headache
- Splenomegaly (can -> rupture)
- Hepatitis + transient ALT rise
- Lymphocytosis (w/ 10% atypical lymphocytes)
- Haemolytic anaemia due to cold agglutins
- Maculopapular, pruritic rash in 99% who take amoxicillin
- Typically resolves in 2-4/52
Investigation
- Monospot test (in 2nd week of illness)
Management
- Supportive
- Rest, analgesia
- Avoid contact sport for 4/52
How is chickenpox exposure in high-risk groups managed?
The following should have post-exposure prophylaxis:
- Significant exposure to chickenpox
- A clinical condition increasing the risk of severe varicella (immunosupressed, neonates + pregnant women)
- No antibodies (test all patients, but don’t let this delay giving PEP past 7d post initial contact)
If above criteria fulfilled:
- VGIG
BCG vaccine - who is given it? What are contraindications? possible side effects?
BCG Vaccine
Indications:
- Neonate (0-12/12), parents or grandparents born somewhere w/ incidence >40/100,000
- above applies to older kids too BUT if >6yo need tuberculin skin test first
- Prev unvaccinated contacts w/ cases of resp TB
- Healthcare workers, elderly care home + prison workers + those working w/ the homeless
Vaccine = live attenuated (can give at same time as other live vaccines but if not given simultaneously then must be 4/52 gap between the doses)
Contraindications: Prev BCG vacc or infect, HIV, pregnancy, +ve skin test
Side effect: lupus vulgaris (as opposed to scrofuloderma which occurs due to skin involvement from adjacent underlying lesion)
What kind of vaccine is influenza? Who is given it? What are possible side effects?
Vaccine Type
- IM = not live
- Intranasal = live (cant give if immunosupressed)
Contraindications for nasal one: immunocompromise, age <2y, current febrile illness or blocked nose, current wheeze, egg allergy, preg/breastfeeding, child taking aspirin
(in IM CI is egg allergy)
Who gets it
- 1st dose 2-3yrs then annually
- >65yo
- Those >6/12 w/ any of the following:
- Chronic resp disease; Chronic heart disease, CKD, Liver disease, neuro disease, DM, immunosupression, asplenia/splenic dysfunction, pregnant women, BMI >40
- Health/social workers, residents in long-stay care homes, carers of elderly/disabled
