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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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1. when HIV patient develop pcp?
Pt who have been treated before for latent TB
High risk 19-64; 1-2 dose - above 65; one dose
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
When cd4 count falls below 200. 2p in pcp =200

2. systolic HTN in elderly
Within 6 months viral load will be <50
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

3. can HIV transmitted through human bite?
Blastomycosis
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

4. infiltrate in upper lobe of lung?
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Monospot test which screen heteropile ab that agglutinate horse rbc
Either TB or aspergillosis
Non pregnant premanopausal - elderly - dm - sci - chronic foley

5. How to confirm dx if pcp?
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Bronchoalveolar washing and transbronchial biopsy
PML; focal neurological deficit like MM; no specific tx; regress with HAART

6. worsening of TB after starting HAART in HIV
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Pegylated interferon and lamivudine
Bronchoalveolar washing and transbronchial biopsy

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

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8. after exposure of HIV when antibody testing is performed?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
ELISA; initial visit - 6 - 12 and 24 weeks;
Pt who have been treated before for latent TB
When cd4 count falls below 200. 2p in pcp =200

9. acute febrile reaction develops after starting penicilin tx to syphilis patient
Either TB or aspergillosis
Bronchoalveolar washing and transbronchial biopsy
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

10. if a patient received BCG vaccine - how big is his PPD induration

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11. What is fatal consequence of RMSF?
Others lesions are ring enhancing and have mass effect while PML don't
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

12. which heart valve is closer to ventricular conduction system/
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Aortic valve; endocardiits of AR p/w AV block and LBBB
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

13. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
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
Upper lobes; any fibrosis in this area suggestive of latent TB
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Pregnacy - urologic procedure - hip arthoplastu

14. How to dx adequate response to HBV vaccine
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Vaccine titer >10mU/ml
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

15. How to tx pcp?
Every 3-4 hours to determine appropritate time to start HAART
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

16. how CMV presents in immunocompromised patients
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Pt who have been treated before for latent TB
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. INH
<500 copies/ml
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

18. When to tx asymptomatic bacteriurea >100 -000?
Pregnacy - urologic procedure - hip arthoplastu
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
PML; focal neurological deficit like MM; no specific tx; regress with HAART

19. what if monospot test is neg in IM?
Viral load and CD4 count
Mainly clinical - epidemiological and seasonal setting
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Do EBV antibody test

20. what would be viral load after 4 weeks
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Mainly clinical - epidemiological and seasonal setting
<5000 copies/ml
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

21. What is the classic signs of nec fasc?
When cd4 count falls below 200. 2p in pcp =200
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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
Upper lobes; any fibrosis in this area suggestive of latent TB

22. What is tx for herpes zoster
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
Acyclovir
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
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

23. How to tx IM?
Pregnacy - urologic procedure - hip arthoplastu
Cd4 count
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

24. hypertension in children
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Immune mediated; circulating IgG and IgM to penicillin derivatives
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

25. How long we tx chronic prostatis?
Blastomycosis
Within 6 months viral load will be <50
6-12 weeks
Aortic valve; endocardiits of AR p/w AV block and LBBB

26. What is difference between uti relapse versus recurrence?
PML; focal neurological deficit like MM; no specific tx; regress with HAART
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
Upper lobes; any fibrosis in this area suggestive of latent TB
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

27. what would be viral load after 2-4m of HAART?
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
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
<500 copies/ml
Monospot test which screen heteropile ab that agglutinate horse rbc

28. How to dx?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Mainly clinical - epidemiological and seasonal setting

29. When to give prophylaxis against MAC
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
<5000 copies/ml
Monospot test which screen heteropile ab that agglutinate horse rbc
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

30. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
Others lesions are ring enhancing and have mass effect while PML don't
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
<5000 copies/ml
PML; focal neurological deficit like MM; no specific tx; regress with HAART

31. What is the mch of ampicillin induced rash in IM
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Immune mediated; circulating IgG and IgM to penicillin derivatives
Monospot test which screen heteropile ab that agglutinate horse rbc
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

32. wisconsin - missisipi - ohio
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Blastomycosis
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
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

33. When not to tx asymptomatic bacteriura?
Voriconazol. mycetoma-surgical removal
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

34. pneumococcal vaccine indication?
High risk 19-64; 1-2 dose - above 65; one dose
Similar pathophysiology as ITP - tx zidovudine
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
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

35. What are indicators for progression of HIV
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
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Rifampin600mg q12. or cipro
Viral load and CD4 count

36. What is used for prophylaxis against meningo..meningitis?
ELISA and western blot of synovial fluid.
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
Rifampin600mg q12. or cipro
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

37. How to tx TSS?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
If a sample is ELISA positive - it is tested fro western blot for confirmation
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

38. How often HIV postiive patients CD4 count needs to be evaluated?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
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
Every 3-4 hours to determine appropritate time to start HAART

39. rifampin
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
ELISA and western blot of synovial fluid.
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Blastomycosis

40. low grade fever - maculopapular rash - lymphadenopathy
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

41. How to tx chronic hep B
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
Cd4 count
Pegylated interferon and lamivudine
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.

42. how HAART therapy affects HIV viral loads?
Immune mediated; circulating IgG and IgM to penicillin derivatives
Monospot test which screen heteropile ab that agglutinate horse rbc
Within 6 months viral load will be <50
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

43. How to differentiate different types of necrotizing fascitis?
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
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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Clostridium perfringens after penetrative injuries/wounds

44. What are the behavioral interventions decrease the risk of UTI
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Postcoital voiding - increased intake of cranberry juice

45. When to give abx to prevent recurrent uti
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
Upper lobes; any fibrosis in this area suggestive of latent TB
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

46. thrombocytopenia in HIV
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Postcoital voiding - increased intake of cranberry juice
Similar pathophysiology as ITP - tx zidovudine

47. What is the pathophysiology of Meningococcal meningitis?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Blastomycosis
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

48. How to give postexposure prophylaxis for HIV
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Voriconazol. mycetoma-surgical removal

49. How to dx cryptococal meninggits
Within 6 months viral load will be <50
Cd4 count
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

50. aspergillosis
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Others lesions are ring enhancing and have mass effect while PML don't
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Voriconazol. mycetoma-surgical removal