Infectious diseases and STIs Flashcards

Question

leprosy - 2 types - mx

Answer 1

· Mx: rifampicin, dapsone, clofazimine Low degree of cell mediated immunity → lepromatous leprosy ('multibacillary') • extensive skin involvement • symmetrical nerve involvement High degree of cell mediated immunity → tuberculoid leprosy ('paucibacillary') - limited skin disease - asymmetric nerve involvement → hypesthesia - hair loss DETAILS · granulomatous disease · primarily affecting the peripheral nerves and skin · Cause: Mycobacterium leprae. Features • patches of hypopigmented skin - buttocks, face, and extensor surfaces of limbs • sensory loss The degree of cell mediated immunity determines the type of leprosy a patient will develop.

Answer 2

Animal bite: co-amox - Pen-allergic: doxy + metro Human bite: co-amox

Answer 3

Black painless eschar Tx with cipro NOTES Cause: bacillus anthracis (aerobic) Fts: - 2-5ds after inoculation: itchy vesicle - Rapidly progresses >> painless black eschar (cutaneous malignant pustule but no pus) - Usually not tender - Can be oedema ++ around the lesion (can > compartment syn or nec fasc) - Regional lymphadenopathy - Can cause GI bleeding

Answer 4

Cause: salmonella (aerobic gram neg rods) Features • initially systemic upset(headache/fever/arthralgia) • relative bradycardia • abdominal pain, distension • Constipation • rose spots: on the trunk in 40%, more common in paratyphoid Comps - osteomyelitis (esp sickle cell disease) - GI bleed/perforation - meningitis - cholecystitis - chronic carriage (1%, more likely if adult females) DETAILS - Salmonella group contains many members: most cause diarrhoeal diseases ○ aerobic, Gram-negative rods ○ not normally present as commensals in the gut. Typhoid: salmonella typhi Parathyroid: salmonella paratyphi (types A, B & C) - enteric fevers: systemic symptoms such as headache, fever, arthralgia. Pathophysiology • typhoid is transmitted via faecal-oral route (also contaminated food and water) Tx: cipro - But if been to asia, probs resistant: azithromycin - Severe: IV cef - 14ds 3rd week of illness bowel perf Dx: large volume blood culture

Answer 5

Inhibits release of Ach at synapses Diff to GBS as botulism descends As soon as clinical suspicion: give botulism antitoxin & supportive care NOTES Tx: botulism antitoxin and supportive care • Antitoxin only effective if given early: once toxin has bound, its actions cant be reversed ``` Ft • Fully conscious, no sensory disturbance • Flaccid paralysis • Double vision • Ataxia • Bulbar palsy ``` Clostridium botulinum • Gram +ve anaerobic bacillus • Produces botulinum toxin: irreversibly blocks release of Ach • Cause: contam food, IVDU

Answer 6

Do an LP if no signs of raised ICP In community and suspect meningococcal: IM benpen (if doesn't delay transfer to hospital) Initial abx · <3mos: IV cefotaxime + amoxicillin (or ampicillin) · 3mos-50y old: IV cefotaxmine (or ceftriaxone) · >50y old: IV cefotaxime/ceftriaxone + amoxicllin/ampicillin Know the type · Meningococcal: IV benpen or cefotaxime/ceftriaxone · Pneumococcal/haemophilus influenzae: IV cefotaxime/ceftriaxone · Listeria: IV amoxicillin/ampicillin + gentamicin Hx of immediate hypersens to penicillin/cephalosporins: use chloramphenicol. Also: IV dex (reduce risk of neuro comps - But don’t give if: septic shock, meningococcal septicaemia, immunocomp, meningitis after surgery Contacts of meningococcal meningitis - Oral cipro (1 dose)

Answer 7

Cysticercosis • Cause: Taenia solium (from pork) and Taenia saginata (from beef) • management: niclosamide Hydatid disease - Cause: dog tapeworm Echinococcus granulosus management: albendazole

Answer 8

Cause: gram-negative bacterium Burkholderia pseudomallei Treatment: • Initial intensive therapy: IV ceftazidime, imipenem, or meropenem for 10–14 days • Then eradication therapy: oral TMP/SMX (plus doxycycline) for 3–6 months • Adjunct therapy: abscess drainage. Risk factors: • DM (the strongest risk factor) • Chronic renal, liver, or lung disease (e.g., cystic fibrosis) • Immunocompromised states (e.g., malignancy, long-term glucocorticoid use) • Occupational exposure: agricultural work Sign and symptoms: • Incubation period: 1-21 days ( mean around 9 days) • Sym cases can be acute, chronic (> 2 months), or reactivations of latent infection. • Clinical features depend on the infected organ: Acute pulmonary infection (most common): wide range of presentations (mild to severe) • - Localized infection: skin ulcer, nodule, or abscess. • - Visceral abscesses: esp in prostate, spleen, kidney, and liver. • - Disseminated infection: ∼ 55% of cases; 20% mortality rate. Manifests with fever and septic shock. Diagnosis: • Culture: the mainstay of diagnosis. Gram stain of sputum or abscess pus • Imaging: Chest radiography: may show signs of acute pneumonia

Answer 9

Rash, headache + 1 or more eschars & history of foreign travel • Weil-felix reaction +ve • Tx: tetracyclines (doxycycline etc) Except Q fever: pneumonia with no rash (coxiella burnetti) • -ve weil-felix reaction NOTES = gram –ve obligate intracellular parasites - Usually rash, headache and fever ``` Rocky mountain spotted fever • Rickettsia ricketsii • Tick • Headache + fever • Rash starts on wrists/ankles > centrally (maculopap > vasculitic) • Endemic to east coast of US ``` Endemic typhus • R typhi • Flea • Rash starts central > peripheral Epidemic typhys • R prowazekii • Human body louse Ehrlichliosis: ehrlichia, tick.

Answer 10

P24 antigen: positive from 1wk to 3-4wk after infection HIV Ab: most dev at 4-6wk, 99% by 3months • Most common and accurate. Screening ELISA and confirmatory western blot

Answer 11

Serological tests can be divided into: • cardiolipin tests (not treponeme specific) • treponemal-specific antibody tests Cardiolipin tests • syphilis infection > production of non-specific antibodies that react to cardiolipin • EG VDRL (Venereal Disease Research Laboratory) & RPR (rapid plasma reagin) • insensitive in late syphilis • becomes negative after treatment Treponemal specific antibody tests • example: TPHA (Treponema pallidum HaemAgglutination test) • remains positive after treatment Therefore, following treatment for syphilis: • VDRL becomes negative • TPHA remains positive ``` Causes of false positive cardiolipin tests (positive VDRL, negative EIA/TPPA): - pregnancy - SLE, anti-phospholipid syndrome - TB - leprosy - malaria - HIV Other treponemal infections (yaws, pinta) ```

Answer 12

Painful: herpes much more common than chancroid Painless: syphilis much more common than LGV NOTES Genital herpes: multiple painful ulcers Syphilis primary chancre: a painless ulcer Chancroid: painful ulcer w sharply defined, ragged, undermined border + unilat painful LN enlargement LGV: small painless pustule > ulcer. Then painful inguinal LN. then proctocolitis Other causes of genital ulcers - Behcet's disease - carcinoma granuloma inguinale: Klebsiella granulomatis

Answer 13

entamoeba histolytica

Answer 14

1ST line immune response to aspergillus: macrophages Tx voriconazole CT: halo sign If suspect aspergilloma from CXR, next test: serology for aspergillus precipitins NOTES = mycetoma (mass like fungal ball) - Often in existing cavity in lung (TB, cancer, CF) Usually asym But can have cough, haemoptysis Ix - CXR: round opacity, crescent sign - High titres of aspergillus precipitins

Answer 15

Mechanism: interferes w DNA synth by inhibiting dihydrofolate reductase - So can interact w methotrexate (also inh DHR) Adverse effects • myelosuppression • transient rise in creatinine Use in pregnancy - Teratogenic risk in first trimester (folate antagonist) - Manufacturers advise avoid during pregnancy DETAILS More on Cr trimethoprim competitively inh the tubular secretion of creatinine - >> in a temporary increase which reverses upon stopping the drug - It blocks the ENaC channel in the distal nephron > hyperkalaemic distal RTA (type 4)

Answer 16

Tx: doxycycline or macrolide Ass w erythema multiforme, cold AI haemolytic anaemia Notes important to recognise atypical pneumonia: may not respond to penicillins or cephalosporins due to it lacking a peptidoglycan cell wall. Features • prolonged and gradual onset • flu-like sym then dry cough • CXR: bilateral consolidation Complications • cold agglutins (IgM): haemolytic anaemia, thrombocytopenia • erythema multiforme, erythema nodosum • meningoencephalitis, GBS and other immune-mediated neurological diseases • bullous myringitis: painful vesicles on the tympanic membrane • pericarditis/myocarditis • GI: hepatitis, pancreatitis • renal: acute glomerulonephritis Investigations - diagnosis is generally by Mycoplasma serology - positive cold agglutination test

Answer 17

- NRTIs: end in 'ine' - Pis: end in 'vir' NNRTIs: nevirapine, efavirenz

Answer 18

Characteristic features of measles include - a prodromal illness with fever, cough and conjunctivitis. - Koplik spots, characteristic lesions of the oral mucosa, may appear during the prodromal phase before the rash. ○ However, while Koplik spots are specific to measles, they are not always present which can make the clinical diagnosis more difficult. - The rash then starts behind the ears or on the face and spreads to the chest. Measles can cause severe complications in pregnancy as it is a state of immunocompromise - complications such as pneumonia are more common. - Public Health England recommends taking a thorough vaccination history at booking. - Post-exposure prophylaxis with human normal immunoglobulin is recommended for susceptible pregnant women who have been exposed to measles. Rubella Similar rash No or much milder prodrome Less high fever

Answer 19

katayama fever - acute schiso

Answer 20

C.botulinum: flaccid paralysis | C.tetani: spastic paralysis

Answer 21

PC: severe tonsillitis + neck swelling Comps: myocarditis, rhythm abnormalities (esp heart block) NOTES Cause: gram positive, Corynebacterium diphtheriae - produces exotoxin - Transmitted via resp droplets Diphtheria toxin > diphtheric membrane on tonsils (caused by necrotic mucosal cells) - Systemic distribution can > necrosis of myocardial, neural and renal tissue Possible presentations • recent visitors to Eastern Europe/Russia/Asia • sore throat w 'diphtheric membrane' - grey, pseudomembrane on the posterior pharyngeal wall • bulky cervical lymphadenopathy ('bull neck') • neuritis e.g. cranial nerves • heart block - ass w poor prognosis Ix: culture of throat swab: uses tellurite agar or Loeffler's media Management • intramuscular penicillin • diphtheria antitoxin

Answer 22

PCP: tx co-trimoxazole, add in steroids if hypoxic (eg pO2 <9) Key bits - Pneumothorax is a common comp - CD4 <200 = should have prophylaxis - Extrapulmonary manifestations are rare but incl: hepatosplenomeg, lymphadenopathy & choroid lesions - Def dx = BAL w silver stain Notes - Fts: SOB, dry cough, fever, v few chest signs - CXR usually bilat interstitial infiltrates but can get lobar consol or be normal - Sputum often negative - Often need BAL to see PCP (silver stain) - Need IV pentamidine in severe cases; or can give aerolised pentamidine (less effective and risk of pneumothorax) Details - Pneumocystic jiroveci = unicellular eukaryote - Co-trimoxazole = trimethoprim + sulfamethoxazole

Answer 23

supportive tx | may need nitazoxanide if immunosuppressed

Answer 24

If immunosuppressed and exposed to chickenpox: check for varicella Abs - If negative (or can't test): give VZ Ig NOTES Criteria to benefit from prophylaxis 1. Sig exposure to chickenpox or herpes zoster 2. Immunosuppressed (steroids longterm, methotrexate, other immunosup; neonates; pregnant) 3. No antibodies to varicella (NB shouldn't delay getting Ig past 7ds of initial contact)

Answer 25

- Binds with ergosterol forming a transmembrane channel that leads to monovalent ion (K+, Na+, H+ and Cl) leakage > cell death - SE: Nephrotoxicity, flu-like symptoms, hypokalaemia, hypomagnaseamia, hepatic failure Used for systemic fungal infections

Answer 26

Reversal of sleep wake cycle + behavioural changes = trypanosomiasis (african sleeping sickness

Answer 27

) NOTES African trypanosomiasis (sleeping sickness) Gambiense in west africa Rhodesiense east africa - more acute course Both spread by tsetse fly Fts 1. Painless SC nodule at site of infection (trypanosoma chancre) 2. Intermittent fever 3. Enlarged LNs (post cervical) 4. Later: CNS involved (somnolence, headache, mood change, meningoenceph) Early: IV pentamidine or suramin Late or cns: IV melarsoprol

Answer 28

``` American trypanosomiasis (chagas' disease) Trypanosoma cruzi ``` Acute - Most asym - But can see erythematous nodule at site of infection + periorbital oedema Chronic - Heart: myocarditis > dilated cardiomyopathy (apical atrophy) + arrthymias - GI: megaoesophagus, megacolon [dysphagia, constipation] Mx: - Acute: azole or nitro deriv EG benznidazole or nifurtimox Chronic: tx the complications

Answer 29

Cause: borrelia burgdorferi (spirochaete) Spread: ticks Fts - Erythema migrans (bulls eye rash): 1-4wks after bite. Painless - Systemic fts: headache, lethargy, fever, arthralgia - Later: CV (heart block, peri/myocarditis), neuro (facial nerve palsy, meningitis, radicular pain) Dx: - Erythema migrans = clinical dx = start abx - No EM: ELISA Abs to BB ○ If done within 4wks of syms and negative but still suspect it: repeat 4-6wk after 1st ELISA ○ If still suspect in syms for 12wks or more: immunoblot test ○ If ELISA positive or equivocal: immunoblot (western blotting) Mx - Early disease: doxy (if CI: amoxicllin) - Disseminated: ceftriaxone Jarisch-herxheimer sometimes after start tx (fever, rash, tachycardia after 1st dose)

Answer 30

· Acute toxo in normal pt can mimic acute EBV infection + should be suspected if EBV serology is negative ○ Need to pregnancy test due to risk of congenital toxo ○ Low fever, lymphoadenopathy w prominent cervical LNs, malaise, sore throat Glandular fever: worst sore throat ever.

Answer 31

NB: similar to dengue but: - more joint pain - no rash usually - Normal bloods (dengue can cause low plts) NOTES Symptoms: - severe joint pain + abrupt onset of high fever - Others: ○ general flu-like illness of muscle ache, headache, and fatigue. ○ A rash may develop ○ swelling of the joints is not uncommon. Similar to dengue but more joint pain which can be debilitating. Treatment: Relief of symptoms. DETAILS · Alphavirus disease · caused by infected mosquitoes. · Africa, Asia and Indian subcontinent - few cases in Southern Europe recently

Answer 32

· HIV transmission rate from 1 needle stick 0.3% · Viral load determines the risk of HIV transmission after a needle stick · Oral ART for 4 weeks Combo ART (tenofovir, emtricitabine and ritonavir/lopinavr), repeat HIV test in 12wk (as takes this long to dev Abs)

Answer 33

: co-existent infection w chlamydia

Answer 34

- BCG, MMR, flu, oral rotavirus, oral polio, oral typhoid, yellow fever Live attenuated vaccines are CI in pts w CD4 <200 (risk of vaccine-ass disease)

Answer 35

Visceral leishmaniasis (kala-azar) • mostly caused by Leishmania donovani (visceral reaction to jason donovan) • Mediterranean, Asia, South America, Africa Fts • fever, sweats, rigors • massive splenomegaly. hepatomegaly • poor appetite*, weight loss • grey skin - 'kala-azar' means black sickness • pancytopaenia secondary to hypersplenism • the gold standard for diagnosis is bone marrow or splenic aspirate *occasionally patients may report increased appetite with paradoxical weight loss

Answer 36

``` Types of drug • Gravir = integrase inh • 'Vir' = PI • 'ine' = NRTI • NNRTI = nevirapine, efavirenz ``` Mech of drugs • Integrase inhibitors (gravirs): block the enz that inserts the viral genome into the DNA of the host cell

Answer 37

cavitating lesions when it causes pneumonia | After flu

Answer 38

E. coli O157:H7 causes HUS - Bloody diarrhoea, acute renal failure w high urea and hamolytic anaemia (schistocytes on blood film) NOTES E. coli O157:H7 - severe, haemorrhagic, watery diarrhoea - high mortality rate - can be complicated by haemolytic uraemic syndrome often spread by contaminated ground beef.

Answer 39

infertility due to PID

Answer 40

Features - prodrome: headache, fever, agitation - hydrophobia: water-provoking muscle spasms - hypersalivation - Negri bodies: cytoplasmic inclusion bodies found in infected neurons Following an animal bite in at-risk countries: - the wound should be washed - if already immunised: 2 further doses of vaccine - not previously immunised: human rabies Ig + full course of vaccination. ○ If possible, the dose should be administered locally around the wound DETAILS - viral disease - causes an acute encephalitis - RNA rhabdovirus (specifically a lyssavirus) - has a bullet-shaped capsid Cause - Most: dog bites - But can be transmitted by bat, raccoon and skunk bites. Following a bite the virus travels up the nerve axons towards the CNS in a retrograde fashion. Mortality - 25,000-50,000 people across the world each year - The vast majority of the disease burden falls on people in poor rural areas of Africa and Asia. - Children are particularly at risk. 'no risk' of developing rabies following an animal bite in the UK and the majority of developed countries. If untreated the disease is nearly always fatal.

Answer 41

retro-orbital headache, fever, facial flushing, rash, thrombocytopenia in returning traveller Investigations • Bloods: leukopenia, thrombocytopenia, raised aminotransferases • diagnostic tests ○ serology ○ nucleic acid amplification tests for viral RNA ○ NS1 antigen test Treatment - entirely symptomatic e.g. fluid resuscitation, blood transfusion etc - no antivirals are currently available ``` MORE Dengue fever • fever • headache (often retro-orbital) • myalgia, bone pain and arthralgia ('break-bone fever') • pleuritic pain • facial flushing (dengue) • maculopapular rash • haemorrhagic manifestations e.g. positive tourniquet test, petechiae, purpura/ecchymosis, epistaxis • 'warning signs' include: ○ abdominal pain ○ hepatomegaly ○ persistent vomiting ○ clinical fluid accumulation (ascites, pleural effusion) ``` Severe dengue (dengue haemorrhagic fever) • A form of DIC resulting in: ○ thrombocytopenia ○ spontaneous bleeding • 20-30% of these go on to dev.dengue shock syndrome (DSS)

Answer 42

``` Cause: Vibro cholerae - Gram negative bacteria Features • profuse 'rice water' diarrhoea • dehydration • hypoglycaemia Management • oral rehydration therapy antibiotics: doxycycline, ciprofloxacin ```

Answer 43

Causes: rheumatic fever, scarlet fever, post-strep GN, erysipelas, impetigo, cellulitis, type 2 nec fasc, pharyngitis/tonsillitis

Answer 44

RIPE for 12mos + prednisolone

Answer 45

``` Features of severe • schizonts on a blood film • parasitaemia > 2% • acidosis • temperature > 39 °C • severe anaemia • comps ``` ``` Complications • cerebral malaria: seizures, coma • acute renal failure: blackwater fever, secondary to intravascular haemolysis • ARDS • hypoglycaemia DIC ``` Severe falciparum malaria - parasite counts >2% usually need parenteral treatment irrespective of clinical state - IV artesunate - if parasite count > 10% consider exchange transfusion shock may indicate coexistent bacterial septicaemia - malaria rarely causes haemodynamic collapse

Answer 46

If had 5 doses of tetanus vaccine with last one <10y ago: do NOT need vaccine booster or Ig (no matter how bad the wound is) Full course of vaccines, last dose >10y ago: - Tetanus prone wound: 1 more dose of vaccine - High risk: 1 more vaccine dose & Ig If vaccine history unknown/incompolete: - All get booster dose If tetanus prone or high risk: also give Ig

Answer 47

· Disseminated infection = tenosynovitis, migratory polyarthritis + dermatitis

Answer 48

cipro | • antibiotics if severe disease, who are immunocomp or with bloody diarrhoea - cipro

Answer 49

* diarrhoeal illnesses * UTIs * neonatal meningitis