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
