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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Pregnacy - urologic procedure - hip arthoplastu
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

2. Tx of choice for human bites
Vaccine titer >10mU/ml
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.
<5000 copies/ml
Ampicillin-sublactam; most bites contain eikenella

3. when not to give INH therapy if ppd positive and patient asyptomatic
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
Pt who have been treated before for latent TB
If a sample is ELISA positive - it is tested fro western blot for confirmation
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

4. How often HIV postiive patients CD4 count needs to be evaluated?
Pregnacy - urologic procedure - hip arthoplastu
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
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
Every 3-4 hours to determine appropritate time to start HAART

5. which heart valve is closer to ventricular conduction system/
Aortic valve; endocardiits of AR p/w AV block and LBBB
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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
Rifampin600mg q12. or cipro

6. What is the classic signs of nec fasc?
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.
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
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
Aortic valve; endocardiits of AR p/w AV block and LBBB

7. wisconsin - missisipi - ohio
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Blastomycosis
Postcoital voiding - increased intake of cranberry juice
AA gradient >35 or Po2 <70

8. How to dx IM?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

9. clinical manifestation of mucomycosis
Voriconazol. mycetoma-surgical removal
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Oropharyngeal secretions; hence named as kissing disease

10. What is the mch of ampicillin induced rash in IM
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Immune mediated; circulating IgG and IgM to penicillin derivatives
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Similar pathophysiology as ITP - tx zidovudine

11. How to confirm dx if pcp?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Bronchoalveolar washing and transbronchial biopsy
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Oropharyngeal secretions; hence named as kissing disease

12. drugs work well on hypertriglyceridia?
Vaccine titer >10mU/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
Every 3-4 hours to determine appropritate time to start HAART
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

13. How to dx IM?
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
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

14. gas gangrene
Aortic valve; endocardiits of AR p/w AV block and LBBB
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

15. What is used for prophylaxis against meningo..meningitis?
<5000 copies/ml
Rifampin600mg q12. or cipro
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
Postcoital voiding - increased intake of cranberry juice

16. What are the subjective /objective measure of encephalopathy?
Rifampin600mg q12. or cipro
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

17. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Upper lobes; any fibrosis in this area suggestive of latent TB

18. How to dx adequate response to HBV vaccine
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Vaccine titer >10mU/ml
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

19. How to dx progressive multifocal leukoencephalopathy
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
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

20. HIV patient having fat deposition on back of neck and abdomen - like cushing
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
Postcoital voiding - increased intake of cranberry juice
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

21. How to dx lyme arthritis?
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
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

22. What are indicators for progression of HIV
ELISA; initial visit - 6 - 12 and 24 weeks;
Viral load and CD4 count
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Ampicillin-sublactam; most bites contain eikenella

23. INH
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Aortic valve; endocardiits of AR p/w AV block and LBBB
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
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

24. acute febrile reaction develops after starting penicilin tx to syphilis patient
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Mainly clinical - epidemiological and seasonal setting

25. When not to tx asymptomatic bacteriura?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Similar pathophysiology as ITP - tx zidovudine

26. rifampin
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
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
Reddish orange discoloration of urine - feces - sweat - tears - sputum
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

27. How to dx?
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
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
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Mainly clinical - epidemiological and seasonal setting

28. when western blot is done for HIV testing
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
Acyclovir
If a sample is ELISA positive - it is tested fro western blot for confirmation
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

29. low grade fever - maculopapular rash - lymphadenopathy
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Immune mediated; circulating IgG and IgM to penicillin derivatives

30. What is the criteria for Spontaneous bact peritonitis
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Bronchoalveolar washing and transbronchial biopsy
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

31. What is the prognosis of lyme arthritis?
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

32. where TB normally affects
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
HBIG hep B immunoglobulin
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Upper lobes; any fibrosis in this area suggestive of latent TB

33. hypertension in children
When cd4 count falls below 200. 2p in pcp =200
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
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

34. When to tx influenza with antiviral therapy?
Pegylated interferon and lamivudine
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

35. what parameters increases risk of neurosyphilis in HIV patient
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
ELISA; initial visit - 6 - 12 and 24 weeks;
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.

36. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Pt who have been treated before for latent TB
Voriconazol. mycetoma-surgical removal
HBIG hep B immunoglobulin

37. how HAART therapy affects HIV viral loads?
When cd4 count falls below 200. 2p in pcp =200
Within 6 months viral load will be <50
Bronchoalveolar washing and transbronchial biopsy
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.

38. When to tx asymptomatic bacteriurea >100 -000?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Pregnacy - urologic procedure - hip arthoplastu
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
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

39. causative organisms of uti
Immune mediated; circulating IgG and IgM to penicillin derivatives
Blastomycosis
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

40. infiltrate in upper lobe of lung?
Either TB or aspergillosis
Within 6 months viral load will be <50
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

41. aspergillosis
Voriconazol. mycetoma-surgical removal
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
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

42. What is the Tx of STD uretheritis?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
High risk 19-64; 1-2 dose - above 65; one dose
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
Blastomycosis

43. after exposure of HIV when antibody testing is performed?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
ELISA; initial visit - 6 - 12 and 24 weeks;

44. damae that is about to occur?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
HIV viral load

45. what would be viral load after 2-4m of HAART?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
<500 copies/ml
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
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

46. antibiotic with good prostate penetration?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
If a sample is ELISA positive - it is tested fro western blot for confirmation

47. How to confirm chlamydia infection?
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
<5000 copies/ml
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

48. how CMV presents in immunocompromised patients
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
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)

49. How to dx cryptococal meninggits
When cd4 count falls below 200. 2p in pcp =200
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

50. can HIV transmitted through human bite?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit 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
Either TB or aspergillosis
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