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USMLE Step3 Infectious Disease

Subjects : health-sciences, usmle-step-3

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. systolic HTN in elderly
Clostridium perfringens after penetrative injuries/wounds
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Blastomycosis
Every 3-4 hours to determine appropritate time to start HAART

2. When to tx asymptomatic bacteriurea >100 -000?
<5000 copies/ml
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Pregnacy - urologic procedure - hip arthoplastu
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

3. How to dx lyme arthritis?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Monospot test which screen heteropile ab that agglutinate horse rbc
If a sample is ELISA positive - it is tested fro western blot for confirmation
ELISA and western blot of synovial fluid.

4. how HAART therapy affects HIV viral loads?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Within 6 months viral load will be <50
Cd4 count
PML; focal neurological deficit like MM; no specific tx; regress with HAART

5. How to differentiate different types of necrotizing fascitis?
ELISA and western blot of synovial fluid.
Pregnacy - urologic procedure - hip arthoplastu
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Type 1: patient with dm and pvd; caused by staph/GAS/ e coli/bacteroids; type2 - no associated medical illness - caused by laceration - trauma - surgery - IV drug abuse - caused mainly by GAS

6. What are the behavioral interventions decrease the risk of UTI
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Postcoital voiding - increased intake of cranberry juice
Pegylated interferon and lamivudine

7. what would be viral load after 2-4m of HAART?
<500 copies/ml
Viral load and CD4 count
Think about cutaneous cryptococous; lesions looks like molluscus contagiousm. present in face/trunk/anywherer; dx biopsy of lesion which shows granulomatous inflammation with multinucleated giant cell
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

8. hypertension in children
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Think about cutaneous cryptococous; lesions looks like molluscus contagiousm. present in face/trunk/anywherer; dx biopsy of lesion which shows granulomatous inflammation with multinucleated giant cell
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

9. which heart valve is closer to ventricular conduction system/
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Aortic valve; endocardiits of AR p/w AV block and LBBB
Oropharyngeal secretions; hence named as kissing disease
Pts with pseudomonas bacerimia have this. they have perivascular bacterial invasion of the media and adventitia of arteries and veins. then ishcemic necrosis; skin and mucous membrane have nodular patches wtih hemorrhage and ulceration

10. when HIV patient develop pcp?
When cd4 count falls below 200. 2p in pcp =200
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
More than two UTI in six months or more than 3 uti in a year; cipro/bactrim/nitrofurantoin; abx may be given continuous or postcoital

11. How to dx progressive multifocal leukoencephalopathy
Pegylated interferon and lamivudine
Pregnacy - urologic procedure - hip arthoplastu
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Pt who have been treated before for latent TB

12. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Clostridium perfringens after penetrative injuries/wounds
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Vaccine titer >10mU/ml
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

13. What is the indication of corticosteroid in pcp infection?
Oropharyngeal secretions; hence named as kissing disease
AA gradient >35 or Po2 <70
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
ELISA; initial visit - 6 - 12 and 24 weeks;

14. when western blot is done for HIV testing
If a sample is ELISA positive - it is tested fro western blot for confirmation
Aortic valve; endocardiits of AR p/w AV block and LBBB
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

15. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Acyclovir
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

16. What is the classic signs of nec fasc?
No skin changes but pain out of proportion; infection spreads along fascial plane rapidly with blister - erythema - and bullae formation; marked tenderness on palpation - and CREPITUS
When patient is older >65 - pregnant - cardiac of pulmonary disease; patient without above risks are treated when they come within 48 hours of symptom onset
Oropharyngeal secretions; hence named as kissing disease
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

17. what if monospot test is neg in IM?
HBIG hep B immunoglobulin
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Do EBV antibody test
Relapse: infecting organism is same as original infecting organism within 2 weeks of tx completion; recurrence: if the infecting organism is different from that of the original organism

18. How often viral load is monitored after HAART?
ELISA; initial visit - 6 - 12 and 24 weeks;
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
<5000 copies/ml
Need lumbar puncture to relieve pressure; they have high opening pressure >350

19. When not to tx asymptomatic bacteriura?
Tx emptirically both gonococcus and chlamydia; 30% gono have coexsiting chlamydial infection; single dose ceftriaxone for gono and Azithromycin for chlamydia. if no improvement give metronidazol for trichomonas infection
Non pregnant premanopausal - elderly - dm - sci - chronic foley
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

20. What is difference between uti relapse versus recurrence?
Every 3-4 hours to determine appropritate time to start HAART
Similar pathophysiology as ITP - tx zidovudine
Relapse: infecting organism is same as original infecting organism within 2 weeks of tx completion; recurrence: if the infecting organism is different from that of the original organism
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

21. when we see echym gangrenosum?
Pts with pseudomonas bacerimia have this. they have perivascular bacterial invasion of the media and adventitia of arteries and veins. then ishcemic necrosis; skin and mucous membrane have nodular patches wtih hemorrhage and ulceration
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
HIV viral load
Think about cutaneous cryptococous; lesions looks like molluscus contagiousm. present in face/trunk/anywherer; dx biopsy of lesion which shows granulomatous inflammation with multinucleated giant cell

22. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
PML; focal neurological deficit like MM; no specific tx; regress with HAART
HIV viral load
6-12 weeks

23. What is the Tx of STD uretheritis?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Tx emptirically both gonococcus and chlamydia; 30% gono have coexsiting chlamydial infection; single dose ceftriaxone for gono and Azithromycin for chlamydia. if no improvement give metronidazol for trichomonas infection
No skin changes but pain out of proportion; infection spreads along fascial plane rapidly with blister - erythema - and bullae formation; marked tenderness on palpation - and CREPITUS
HIV viral load

24. What is tx for herpes zoster
Acyclovir
More than two UTI in six months or more than 3 uti in a year; cipro/bactrim/nitrofurantoin; abx may be given continuous or postcoital
No skin changes but pain out of proportion; infection spreads along fascial plane rapidly with blister - erythema - and bullae formation; marked tenderness on palpation - and CREPITUS
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

25. What is the Tx of cryptococcal meninngitis
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Aortic valve; endocardiits of AR p/w AV block and LBBB
ELISA and western blot of synovial fluid.

26. What is characteristic for dx of rocky mountain spotted fever?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Cd4 count
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Voriconazol. mycetoma-surgical removal

27. HIV patient having fat deposition on back of neck and abdomen - like cushing
Pregnacy - urologic procedure - hip arthoplastu
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
When patient is older >65 - pregnant - cardiac of pulmonary disease; patient without above risks are treated when they come within 48 hours of symptom onset

28. What is tetanus - diptheria - pertusis recommendation?
Td every 10 years - tdap once before 65 and after 65
Relapse: infecting organism is same as original infecting organism within 2 weeks of tx completion; recurrence: if the infecting organism is different from that of the original organism
Others lesions are ring enhancing and have mass effect while PML don't
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

29. INH
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Pregnacy - urologic procedure - hip arthoplastu
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

30. damae that is about to occur?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
If a sample is ELISA positive - it is tested fro western blot for confirmation
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
HIV viral load

31. What are the subjective /objective measure of encephalopathy?
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Gonococcal with purulent discharges and presence of multiple diplococi and neurotrophils in urethral swab; non gonoccal (chlamydia) are watery disch - swab abacterial - sometimes have intracellular organism

32. How to tx pcp?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Every 3-4 hours to determine appropritate time to start HAART
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

33. How often HIV postiive patients CD4 count needs to be evaluated?
Aortic valve; endocardiits of AR p/w AV block and LBBB
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Every 3-4 hours to determine appropritate time to start HAART
Gonococcal with purulent discharges and presence of multiple diplococi and neurotrophils in urethral swab; non gonoccal (chlamydia) are watery disch - swab abacterial - sometimes have intracellular organism

34. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Pts with pseudomonas bacerimia have this. they have perivascular bacterial invasion of the media and adventitia of arteries and veins. then ishcemic necrosis; skin and mucous membrane have nodular patches wtih hemorrhage and ulceration
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

35. how CMV presents in immunocompromised patients
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
More than two UTI in six months or more than 3 uti in a year; cipro/bactrim/nitrofurantoin; abx may be given continuous or postcoital
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

36. where TB normally affects
HIV viral load
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Upper lobes; any fibrosis in this area suggestive of latent TB
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

37. hypertriglyceridemia in HIV
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
<500 copies/ml
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

38. How long abx is given in pseudomonas infection?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Vaccine titer >10mU/ml
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Think about cutaneous cryptococous; lesions looks like molluscus contagiousm. present in face/trunk/anywherer; dx biopsy of lesion which shows granulomatous inflammation with multinucleated giant cell

39. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Mainly clinical - epidemiological and seasonal setting
Clostridium perfringens after penetrative injuries/wounds
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
If a sample is ELISA positive - it is tested fro western blot for confirmation

40. reddish colored papules with central umbilication in HIV or immunocompromised patient
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Think about cutaneous cryptococous; lesions looks like molluscus contagiousm. present in face/trunk/anywherer; dx biopsy of lesion which shows granulomatous inflammation with multinucleated giant cell
Need lumbar puncture to relieve pressure; they have high opening pressure >350
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

41. What is used for prophylaxis against meningo..meningitis?
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Voriconazol. mycetoma-surgical removal
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Rifampin600mg q12. or cipro

42. when not to give INH therapy if ppd positive and patient asyptomatic
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
<500 copies/ml
Pt who have been treated before for latent TB
AA gradient >35 or Po2 <70

43. What is the mch of ampicillin induced rash in IM
Immune mediated; circulating IgG and IgM to penicillin derivatives
Ampicillin-sublactam; most bites contain eikenella
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

44. How to dx cryptococal meninggits
Postcoital voiding - increased intake of cranberry juice
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Think about cutaneous cryptococous; lesions looks like molluscus contagiousm. present in face/trunk/anywherer; dx biopsy of lesion which shows granulomatous inflammation with multinucleated giant cell

45. How to differentiate gonococcal and nongonoccal urethritis?
Td every 10 years - tdap once before 65 and after 65
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Gonococcal with purulent discharges and presence of multiple diplococi and neurotrophils in urethral swab; non gonoccal (chlamydia) are watery disch - swab abacterial - sometimes have intracellular organism
Within 6 months viral load will be <50

46. How to confirm dx if pcp?
Bronchoalveolar washing and transbronchial biopsy
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Gonococcal with purulent discharges and presence of multiple diplococi and neurotrophils in urethral swab; non gonoccal (chlamydia) are watery disch - swab abacterial - sometimes have intracellular organism
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

47. What are indicators for progression of HIV
Viral load and CD4 count
ELISA; initial visit - 6 - 12 and 24 weeks;
Mainly clinical - epidemiological and seasonal setting
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

48. How to dx adequate response to HBV vaccine
Vaccine titer >10mU/ml
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Reddish orange discoloration of urine - feces - sweat - tears - sputum

49. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Mainly clinical - epidemiological and seasonal setting
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

50. pneumococcal vaccine indication?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Postcoital voiding - increased intake of cranberry juice
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
High risk 19-64; 1-2 dose - above 65; one dose