ID Flashcards
Primary TB
Organism multiples at pleural surface = Ghon focus
Macrophages take TB to LNs, which with lesion is known as Ghon complex
Fibrosis of Ghon complex –> calcified nodule (Ranke complex)
Usually asymptomatic
Rarely in immunocompromised pts progresses to primary progressive TB
Primary progressive:
resembles acute infxn with mid and lower zone consolidation, effusions and bihi lymphad
Lymphohaematogenous spread → milliary TB (diffuse seeding of TB in lung) and extra-pulmonary
Latent and secondary TB
Latent TB:
Infected but no clinical or x-ray signs of active TB, pt is non-infectious
weakened host resistance leads to reactivation
Secondary TB:
reactivation from weakened immune system or reinfxn
typically develops in upper lobes and have cavitation with caseating granulomas
Extrapulmonary TB features
CNS –> meningism with papilloedema and CN palsy (Rx = RIPE 2 months–>RI 10 mo +/- dexamethasone)
GU –> sterile pyuria and symptoms of UTI
LN –>Firm, painless lesions (scrofula) that eventually ulcerate with a granular base with no sign of infxn
skin –> lupus vulgaris (apple-jelly nodules)
adrenals –> addison’s
Ix for TB
Latent TB: tuberculin skin test; if +ve then interferon gamma release assay (IGRA)
NB tuberculin skin test can give false -ve with HIV, sarcoid and lymphoma
Active TB: CXR showing upper lobe caviting lesions –> take 3 sputum samples (or BAL) and use Lowenstein-Jensen culture + Ziehl Neelsen stain
RIPE SE
R: orange urine (+hepatitis)
I: peripheral neuropathy (+hepatitis)
P: hepatitis (C/I: gout, porphyria)
E: optic neuritis
Other mycobacterium
Leprosy / Hansen’s disease
Mycobacterium avium-intracellulare - complicates HIV infxn with wide dissemination in lungs and hepatomegaly
M. ulcerans - Buruli ulcer from initial nodule in Australia
M. marinum - Fish tank granuloma
Leprosy
Tuberculoid
Less severe
TH1-mediated control of bacteria → paucibacillary Anaesthetic hypopigmented macules
Rx = 6 months Rif monthly and clofazamine daily
Lepromatous Weak TH1/2 → multibacillary Skin nodules Nerve damage (esp. ulnar and peroneal) Rx = 2 years Rif monthly clofazamine + dapsone daily
Reyes syndrome
rash, vomiting, ↑LFTs in children recovering from influenza and linked to them being given aspirin
Rx for influenza
Bed rest and paracetamol
If severe:
Mx in ITU
Cipro and co-amoxiclav: prevent Staph and Strep
High risk patients:
Oseltamivir if >1yr with symptoms of <48hr. Can also be use as prophylactic
Zanamivir if >5yrs with symptoms <48h
Trivalent vaccine for: >65yrs DM, COPD, heart, renal, liver failure Immunosuppression: splenectomy, steroids Medical staff
HIV effects
Osteoporosis
Dementia
Neuropathy
Nephropathy
AIDS-related complex (ARC) = AIDS prodrome with FLAWS + minor opportunistic infxns e.g: Oral candida Oral hairy leukoplakia (EBV) Recurrent HSV Seborrhoeic dermatitis
HIV Ix:
ELISA: detect serum (or salivary) anti-HIV Abs
Western Blot: for confirmation
If recent exposure, may be window period; usually 1-3wks but can be 3-6mo
PCR: can detect HIV virions in the window period
Rapid Antibody Tests: false positives are a problem and results should be confirmed by Western Blot
Once HIV confirmed:
CD4 count (<350 is indication for Rx)
viral load
Perform Mantoux test and serology for toxo, CMV, HBV, HCV, syphilis
HAART indications and regimes
Indications CD4 ≤350 AIDS-defining illness Pregnancy HIVAN (associated nephropathy) Co-infected with HBV when Rx is indicated for HBV
Regimens
1 NNRTI + 2 NRTIs
NNRTI = Efavirenz
NRTI = emtricitabine + tenofovir (Truvada)
Atripla = efavirenz + emtricitabine + tenofovir
PI + 2 NRTIs
PI = lopinavir (+ low dose ritonavir = Kaletra)
NB PEP = truvada + Kaletra, continue at least 28 days
Major AIDS illnesses
4Cs 2Ps 2Ts KLM:
Candidiasis: oesophageal or pulmonary
Cryptococcal meningitis - halo on india ink CSF stain
Cryptosporidiosis - chronic diarrhoea
CMV retinitis - pizza sign on fundoscopy
Kapsosi sarcoma - HHV8
Lymphoma: Burkitt’s, 1O brain
MAC - disseminated lung infxn
PCP - bilat perihilar interstitial shadowing with dry cough and exertional dyspnoea
PML
Toxo - ring-shaped contrast enhancing lesion with encephalitis
TB - may have false -ve in tests; also absence of characteristic granuloma (as no immune response). Increasing CD4 paradoxically worsens TB symptoms
Progressive multifocal leukoencephalopathy
Demyelinating inflammation of brain white matter
caused by JC virus.
Presentation Weakness Paralysis Visual loss Cognitive decline
Ix: JC viral PCR
Rx: HAART + mefloquine may halt progression
Toxoplasmosis Rx + prophylaxis:
ring-shaped contrast enhancing lesions
Rx: pyrimethamine + sulfadiazine + folate
Prophylaxis: Co-trimoxazole if CD4 <100 = lifelong 2ndary prophylaxis
Kaposi’s sarcoma Rx
HAART
Radiotherapy or chemotherapy
PCP Rx + prophylaxis:
Rx
High-dose co-trimoxazole IV
Or, pentamidine IVI
Prednisolone if severe hypoxaemia
Prophylaxis
Co-trimoxazole if CD4 <200 or after 1st attack
Cryptococcal meningitis Rx:
Amphotericin B + flucytosine for 2wks then fluconazole for for 6mo / until CD4 >200
CMV retinitis Rx
IV ganciclovir or eye implant of intravitreous ganciclovir
Owl’s eye inclusions seen
Herpes Encephalitis
90% HSV-1, 10% HSV-2 Features: Flu-like prodrome Headache focal neuro e.g. fits, odd behaviour ↓GCS Haemorrhagic necrosis of temporal lobes Rx: IV aciclovir
Mollaret’s Meningitis
HSV-2 mostly
Benign recurrent aseptic meningitis
Rx = IV aciclovir
Herpes Gladiatorum
Rugby players, wrestlers
Features:
Painful vesicular rash, lymphadenopathy, fever
Rx = PO aciclovir
Herpetic Whitlow
Healthcare workers, children
Features:
Painful red finger
Rx = topical aciclovir
Elseberg syndrome
genital herpes leading to sacral radiculomyelitis = urinary retention + sacral sensory loss
Herpetic keratitis
Unilat/bilat conjunctivitis + pre-auricular LNs
May cause a corneal ulcer = dendritic ulcer
Ramsay hunt syndrome
ear herpes zoster, facial palsy, ↓ taste, ↓ hearing
Varicella zoster Dx
Tzanck cells seen from scrapings
EBV Ix
+ve heterophile Ab - either paul bunnell or monospot test
Atypical lymphocytes seen
Burkitt’s lymphoma Ix
Starry-sky appearance CD10, BCL6
t(8;14)
Post-transplant lymphoproliferative disorder
EBV associated lymphoma post solid organ transplant
Rx: rituximab
Oral hairy leukoplakia
Painless shaggy white plaque along lateral tongue border in HIV +ve pts
Rx = aciclovir
Hep B Ix
HBsAg +ve = current infection (+ve >6mo = chronic disease)
HBeAg +ve = high infectivity
Anti-HBc IgM = recent infection
Anti-HBc IgG = past infection
Anti-HBs = cleared infection or vaccinated
HBV PCR: monitoring response to Rx
NB chronic infxn in 5%; can get cryoglobulinaemina
Hep B Rx
Chronic disease: PEGinterferon α2b
Hep C Rx
Indications
Chronic haepatitis
↑ ALT
Fibrosis
Rx = PEGinterferon α2b + ribavirin. ↓ efficacy if: Genotype 1, 4, 5 or 6 ↑ VL Older Black Male
Hep D Ix
anti-HDV Ab
Campyelobacter jejuni
Unpasterised milk or animal feces
Features:
Bloody diarrohoea, fever
Guillain-Barre (ascending paralysis)
Reactive arthritis
Rx: cipro
Listeria
Soft cheese / pates
Features: Watery diarrhoea, cramps, flu-like Pneumonia Meningoencephalitis Miscarriage
Rx: ampicillin
C. botulinum
Canned food:
Kids = honey
students = beans
Features: Afebrile Descending symmetric flaccid paralysis No sensory signs Autonomic: dry mouth, fixed dilated pupils
Rx = antitoxin, benpen + metro
C. perfringes
Reheated meat
Features:
watery diarrhoea + cramps
Rx = benpen + metro
Norovirus
commonest causes in adults
Fever, diarrhoea, projectile vomiting
Rotavirus
commonest cause in children
secretory diarrhoea and vomiting
Typhoid Rx
Cefotaxime or cipro
Yersinia entero
Abdo pain, diarrhoea, fever
Mesenteric adenitis
Reactive arthritis, pharyngitis, pericarditis Erythema Nodosum
Rx = cipro
Entamaeoba histolytica
MSM or travellers
Features Dysentery, wind, tenesmus Wt. loss if chronic Liver abscess - RUQ pain, swinging fever, sweats - Mass in R lobe Flask shaped ulcer on histology - Micro = motile trophozoite with 4 nuclei
Rx = metro or tinidazole if abscess or severe
Giardia Rx
Tinidazole
Jarisch-Herxheimer Reaction
hours after 1st pen dose for syphillis get fever, tachy and vasodilation
Rx = steroids
LGV
Chlamydia L1,2,3
Primary stage:
- painless genital ulcer, heals fast
- balanitis, proctitis, cervicitis
Inguinal Syndrome:
- Painful inguinal buboes
- Fever, malaise
→ genital elephantiasis
Anogenitorectal syndrome:
- Proctocolitis
→ Rectal strictures
→ Abscesses and fistulae
Rx = azithromycin/doxy
Gonorrhoea Rx
IM ceftriaxone + azithromycin for chlam
Granuloma inguinale
Painless beefy-red ulcer from klebsiella
Shows donovan bodies on giemsa stain
Rx = erythromycin
Chancroid
H. ducreyi
Painful ulcer progressing to inguinal buboes
Rx: azithromycin
Argyll-Robertson pupil
accomodates but doesn’t react to light
Tabes dorsalis
Degeneration of sensory neurones, esp. legs
Ataxia and +ve Romberg’s
Areflexia
Plantars ↑↑
Charcot’s joints (occurs in DM as well)
Syphillis Ix
Cardiolipin Ab on VDRL or RPR (not specific)
Treponeme specific Ab via THPA and FTA (remains +ve after Rx)
Treponemes can be seen by dark ground microscopy
Leptospirosis (Weil’s disease)
Infected rat urine
Presentation:
High fever, headache, myalgia / myositis, cough, chest pain ± haemoptysis
± hepatitis with jaundice
± meningitis
Rx = doxycycline
Brucellosis
Unpasteurised milk/cheese
Undulant fever (PUO) which peaks PM and normal AM
Ix: pancytopenia with positive rose bengal test and anti-O-polysaccharide Ag
Rx: doxy + Rifam + gent
Cat scratch disease
Tender regional LN
Rx = azithromycin
Rabies
Bullet-shaped RNA virus and negri bodies
Rx
Immunised = diploid vaccine
Unimmunised = vaccine + rabies Ig
Toxoplasmosis Rx
Pyrimethamine + sulfadiazine
Septrin prohylaxis in HIV
Anthrax features
Spread by infected carcasses or hides
Features
Ulcer with BLACK centre and rim of oedema
Anthrax Ix and Rx
Gram +ve spore forming rod
Rx = cipro + clindamycina
Antimalarial SE
Chloroquine: retinopathy
Fansidar: SJS, ↑LFTs, blood dyscrasias
Primaquine: haemolysis if G6PD deficient
Malarone: abdo pain, nausea, headache
Mefloquine: dysphoria, neuropsychiatric signs
Uncomplicated Ovale, Vivax and Malariae Mx
Chloroquine and primaquine
Uncomplicated falciparum Mx
Artemether-lumefantrine (riamet)
OR
Quinine + Doxy
Severe Falciparum Mx
Need ITU Mx
IV antimalarials
Falciparum Complications
Cerebral malaria: confusion, coma, fits Lactic acidosis → Kussmaul respiration Hypoglycaemia Acute renal failure: 2O to ATN ARDS
Malaria Ix
Serial thick and thin blood films Parasitaemia level FBC: anaemia, thrombocytopenia Clotting: DIC Glucose ABG: lactic acidosis U+E: renal failure Urinalysis: haemoglobionuria
African Trypanosomiasis
Sleeping sickness
Tsetse fly
T. gambiense: West Africa
T. rhodesiense: East Africa
- More severe than gambiense
Posterior cervical nodes (Winterbottom’s sign)
Sleeping sickness occurs months after original infxn
American Trypanosomiasis
Chagas Disease
Reduviids fly: T. cruzi - Erythematous nodule, fever, LN, HSM - Swelling of eyelid (Romana’s Sign) - Cardiac disease
Leishmaniasis
Sandflies:
Cutaneous (Major, tropica)
Mucocutaneous (Braziliensis)
Visceral / Kala Azar (Donovani)
Kala Azar
L Donovani
Features:
- Dry, warty hyperpigmented skin lesions (dark face and hands)
- Prolonged fever
- Massive splenomegaly, LNs, abdo pain
Visualisation of Leishman-Donovan bodies on Ix and pancytopenia
Mucocutaneous leish
Ulcer in mucous mems of mouth and nose
Cutaneous leish
skin ulcer @ bite → depigmented scar
Widespread nodules (fail to ulcerate)
Filariasis
Wuchereria bancrofti
Elephantiasis
Ix:
Eosinophilia
Microfilariae in the blood
Dengue Fever Ix
Tourniquet test
Serology
can exclude if fever starts >2wks after leaving endemic area
Schistosomiasis
Itchy papular rash at site of penetration - Swimmer’s Itch
Schistosomiasis Mansoni
- abdo pain D&V
- later hepatic fibrosis and portal HTN
- HSM
Schistosomiasis Haematobium
- frequency, dysuria, haematuria
- may → hydronephrosis and renal failure
- ↑ risk of bladder SCC
Tetanus Rx
Mx on ITU: may need intubation
Human tetanus Ig
Metronidazole, benpen
Actinomycosis Rx
ampicillin for 30d, then pen V for 100d
From subcut infxn (esp on jaw)