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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. how HAART therapy affects HIV viral loads?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Within 6 months viral load will be <50
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
6-12 weeks

2. What is the Tx of cryptococcal meninngitis
Others lesions are ring enhancing and have mass effect while PML don't
Pregnacy - urologic procedure - hip arthoplastu
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

3. When not to tx asymptomatic bacteriura?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Oropharyngeal secretions; hence named as kissing disease
Non pregnant premanopausal - elderly - dm - sci - chronic foley
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

4. How to tx IM?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
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
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
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

5. after recent exposure - negative ELISA - How to confirm?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Rifampin600mg q12. or cipro
Postcoital voiding - increased intake of cranberry juice
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

6. INH
When cd4 count falls below 200. 2p in pcp =200
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

7. hypertension in children
Either TB or aspergillosis
Every 3-4 hours to determine appropritate time to start HAART
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

8. acute febrile reaction develops after starting penicilin tx to syphilis patient
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Pegylated interferon and lamivudine

9. clinical manifestation of mucomycosis
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Pegylated interferon and lamivudine

10. can HIV transmitted through human bite?
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Ampicillin-sublactam; most bites contain eikenella
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

11. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Cd4 count
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

12. which heart valve is closer to ventricular conduction system/
Cd4 count
Aortic valve; endocardiits of AR p/w AV block and LBBB
Either TB or aspergillosis
Others lesions are ring enhancing and have mass effect while PML don't

13. reddish colored papules with central umbilication in HIV or immunocompromised patient
Within 6 months viral load will be <50
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Need lumbar puncture to relieve pressure; they have high opening pressure >350
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

14. How to differentiate gonococcal and nongonoccal urethritis?
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
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
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Every 3-4 hours to determine appropritate time to start HAART

15. infiltrate in upper lobe of lung?
Do EBV antibody test
Ampicillin-sublactam; most bites contain eikenella
Either TB or aspergillosis
High risk 19-64; 1-2 dose - above 65; one dose

16. systolic HTN in elderly
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
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

17. When to tx influenza with antiviral therapy?
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
AA gradient >35 or Po2 <70
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
6-12 weeks

18. how im is transmitted?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Mainly clinical - epidemiological and seasonal setting
Oropharyngeal secretions; hence named as kissing disease
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

19. How to dx cryptococal meninggits
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

20. what would be viral load after 4 weeks
6-12 weeks
Either TB or aspergillosis
Upper lobes; any fibrosis in this area suggestive of latent TB
<5000 copies/ml

21. Tx of choice for human bites
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Clostridium perfringens after penetrative injuries/wounds
Ampicillin-sublactam; most bites contain eikenella

22. what would be viral load after 2-4m of HAART?
<500 copies/ml
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
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
HIV viral load

23. What is difference between uti relapse versus recurrence?
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
Immune mediated; circulating IgG and IgM to penicillin derivatives
Cd4 count

24. what parameters increases risk of neurosyphilis in HIV patient
HIV viral load
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Reddish orange discoloration of urine - feces - sweat - tears - sputum
CD4 less than 350 and RPR >1:32; HIV infected patient with syphilis >1 yr should have CSF exam before tx. if csf normal tx with benzathine penicillin weekly for 3 weeks.

25. HIV patient having fat deposition on back of neck and abdomen - like cushing
Reddish orange discoloration of urine - feces - sweat - tears - sputum
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Every 3-4 hours to determine appropritate time to start HAART

26. How long we tx chronic prostatis?
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
6-12 weeks
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

27. where TB normally affects
Every 3-4 hours to determine appropritate time to start HAART
<5000 copies/ml
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Upper lobes; any fibrosis in this area suggestive of latent TB

28. What is characteristic for dx of rocky mountain spotted fever?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
<5000 copies/ml
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

29. When to give prophylaxis against MAC
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Postcoital voiding - increased intake of cranberry juice
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

30. What is the indication of corticosteroid in pcp infection?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
AA gradient >35 or Po2 <70
Ampicillin-sublactam; most bites contain eikenella
High risk 19-64; 1-2 dose - above 65; one dose

31. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
If a sample is ELISA positive - it is tested fro western blot for confirmation
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

32. How to dx IM?
6-12 weeks
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Pregnacy - urologic procedure - hip arthoplastu
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

33. When to tx asymptomatic bacteriurea >100 -000?
Vaccine titer >10mU/ml
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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Pregnacy - urologic procedure - hip arthoplastu

34. How to dx?
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Mainly clinical - epidemiological and seasonal setting
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

35. What is the prognosis of lyme arthritis?
Pegylated interferon and lamivudine
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
<5000 copies/ml
When cd4 count falls below 200. 2p in pcp =200

36. How often HIV postiive patients CD4 count needs to be evaluated?
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
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Every 3-4 hours to determine appropritate time to start HAART
Rifampin600mg q12. or cipro

37. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
<500 copies/ml
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Pt who have been treated before for latent TB

38. 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
Similar pathophysiology as ITP - tx zidovudine
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

39. pathophysiology of toxic shock syndrom?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

40. worsening of TB after starting HAART in HIV
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
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
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
Non pregnant premanopausal - elderly - dm - sci - chronic foley

41. How to differentiat PML from toxoxplasmosis - cns lymphoma adn brain abscess

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42. What is the classic signs of nec fasc?
Pt who have been treated before for latent TB
Upper lobes; any fibrosis in this area suggestive of latent TB
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
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

43. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
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
HBIG hep B immunoglobulin
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

44. foot infections in DM
Similar pathophysiology as ITP - tx zidovudine
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

45. What is the Tx of STD uretheritis?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
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
Aortic valve; endocardiits of AR p/w AV block and LBBB
Pegylated interferon and lamivudine

46. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Clostridium perfringens after penetrative injuries/wounds
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
HBIG hep B immunoglobulin

47. when HIV patient develop pcp?
Viral load and CD4 count
When cd4 count falls below 200. 2p in pcp =200
Mainly clinical - epidemiological and seasonal setting
Oropharyngeal secretions; hence named as kissing disease

48. What are the subjective /objective measure of encephalopathy?
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Aortic valve; endocardiits of AR p/w AV block and LBBB
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Non pregnant premanopausal - elderly - dm - sci - chronic foley

49. What is the pathophysiology of Meningococcal meningitis?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Viral load and CD4 count
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

50. thrombocytopenia in HIV
Others lesions are ring enhancing and have mass effect while PML don't
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Similar pathophysiology as ITP - tx zidovudine
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease