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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. 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
Pt who have been treated before for latent TB
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Postcoital voiding - increased intake of cranberry juice

2. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
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)
PML; focal neurological deficit like MM; no specific tx; regress with HAART
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.

3. INH
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Cd4 count
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

4. What is the prognosis of lyme arthritis?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Need lumbar puncture to relieve pressure; they have high opening pressure >350

5. What are the subjective /objective measure of encephalopathy?
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
If a sample is ELISA positive - it is tested fro western blot for confirmation
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

6. antibiotic with good prostate penetration?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

7. when not to give INH therapy if ppd positive and patient asyptomatic
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Pt who have been treated before for latent TB
AA gradient >35 or Po2 <70
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

8. damae that is about to occur?
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
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.
HIV viral load

9. how im is transmitted?
Ampicillin-sublactam; most bites contain eikenella
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Oropharyngeal secretions; hence named as kissing disease

10. how CMV presents in immunocompromised patients
Monospot test which screen heteropile ab that agglutinate horse rbc
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Bronchoalveolar washing and transbronchial biopsy
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

11. How to give postexposure prophylaxis for HIV
Pregnacy - urologic procedure - hip arthoplastu
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Ampicillin-sublactam; most bites contain eikenella

12. after exposure of HIV when antibody testing is performed?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
ELISA; initial visit - 6 - 12 and 24 weeks;
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

13. gas gangrene
Pegylated interferon and lamivudine
Monospot test which screen heteropile ab that agglutinate horse rbc
Clostridium perfringens after penetrative injuries/wounds
Voriconazol. mycetoma-surgical removal

14. What is characteristic for dx of rocky mountain spotted fever?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Need lumbar puncture to relieve pressure; they have high opening pressure >350

15. thrombocytopenia in HIV
If a sample is ELISA positive - it is tested fro western blot for confirmation
Similar pathophysiology as ITP - tx zidovudine
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Reddish orange discoloration of urine - feces - sweat - tears - sputum

16. INH
Rifampin600mg q12. or cipro
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Do EBV antibody test

17. after recent exposure - negative ELISA - How to confirm?
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
Voriconazol. mycetoma-surgical removal
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
AA gradient >35 or Po2 <70

18. What is the Tx of cryptococcal meninngitis
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Others lesions are ring enhancing and have mass effect while PML don't
Reddish orange discoloration of urine - feces - sweat - tears - sputum

19. where TB normally affects
Bronchoalveolar washing and transbronchial biopsy
<500 copies/ml
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Upper lobes; any fibrosis in this area suggestive of latent TB

20. When to give prophylaxis against MAC
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Others lesions are ring enhancing and have mass effect while PML don't
Clostridium perfringens after penetrative injuries/wounds
Upper lobes; any fibrosis in this area suggestive of latent TB

21. What is the Tx of STD uretheritis?
When cd4 count falls below 200. 2p in pcp =200
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
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

22. How often HIV postiive patients CD4 count needs to be evaluated?
Rifampin600mg q12. or cipro
Every 3-4 hours to determine appropritate time to start HAART
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

23. When to tx influenza with antiviral therapy?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
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
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
Oropharyngeal secretions; hence named as kissing disease

24. rifampin
HBIG hep B immunoglobulin
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Aortic valve; endocardiits of AR p/w AV block and LBBB
Reddish orange discoloration of urine - feces - sweat - tears - sputum

25. what parameters increases risk of neurosyphilis in HIV patient
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
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
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.
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

26. systolic HTN in elderly
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Do EBV antibody test
AA gradient >35 or Po2 <70
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

27. What is lag time to develop lyme arthritis after exposure to vector
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Td every 10 years - tdap once before 65 and after 65
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

28. What is tx for herpes zoster
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Acyclovir
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

29. how HAART therapy affects HIV viral loads?
Td every 10 years - tdap once before 65 and after 65
Within 6 months viral load will be <50
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

30. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
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
HBIG hep B immunoglobulin
Every 3-4 hours to determine appropritate time to start HAART
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

31. wisconsin - missisipi - ohio
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Blastomycosis
Need lumbar puncture to relieve pressure; they have high opening pressure >350

32. pneumococcal vaccine indication?
Every 3-4 hours to determine appropritate time to start HAART
High risk 19-64; 1-2 dose - above 65; one dose
Mainly clinical - epidemiological and seasonal setting
Viral load and CD4 count

33. 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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Viral load and CD4 count
6-12 weeks

34. dame that has already occurred
Cd4 count
Blastomycosis
Either TB or aspergillosis
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

35. What is fatal consequence of RMSF?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Vaccine titer >10mU/ml
Viral load and CD4 count
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

36. How to dx lyme arthritis?
Acyclovir
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
ELISA and western blot of synovial fluid.
Monospot test which screen heteropile ab that agglutinate horse rbc

37. How to tx pseudomonas?
Similar pathophysiology as ITP - tx zidovudine
Bronchoalveolar washing and transbronchial biopsy
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
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

38. clinical manifestation of mucomycosis
Vaccine titer >10mU/ml
Do EBV antibody test
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

39. 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
Monospot test which screen heteropile ab that agglutinate horse rbc
Td every 10 years - tdap once before 65 and after 65
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

40. when HIV patient develop pcp?
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
When cd4 count falls below 200. 2p in pcp =200
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Non pregnant premanopausal - elderly - dm - sci - chronic foley

41. When to tx asymptomatic bacteriurea >100 -000?
Pregnacy - urologic procedure - hip arthoplastu
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Immune mediated; circulating IgG and IgM to penicillin derivatives
Upper lobes; any fibrosis in this area suggestive of latent TB

42. How to dx progressive multifocal leukoencephalopathy
Cd4 count
Upper lobes; any fibrosis in this area suggestive of latent TB
Similar pathophysiology as ITP - tx zidovudine
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

43. How to dx cryptococal meninggits
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.
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
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
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

44. which heart valve is closer to ventricular conduction system/
Cd4 count
ELISA; initial visit - 6 - 12 and 24 weeks;
Aortic valve; endocardiits of AR p/w AV block and LBBB
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

45. when western blot is done for HIV testing
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
6-12 weeks
If a sample is ELISA positive - it is tested fro western blot for confirmation

46. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Cd4 count
Need lumbar puncture to relieve pressure; they have high opening pressure >350
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
AA gradient >35 or Po2 <70

47. What is the classic signs of nec fasc?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
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
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

48. How to tx chronic hep B
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Pegylated interferon and lamivudine
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

49. What is used for prophylaxis against meningo..meningitis?
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Rifampin600mg q12. or cipro
Reddish orange discoloration of urine - feces - sweat - tears - sputum

50. hypertriglyceridemia in HIV
Td every 10 years - tdap once before 65 and after 65
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
If a sample is ELISA positive - it is tested fro western blot for confirmation