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USMLE Step3 Infectious Disease

Subjects : health-sciences, usmle-step-3

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
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. HIV patient having fat deposition on back of neck and abdomen - like cushing
Within 6 months viral load will be <50
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Voriconazol. mycetoma-surgical removal

2. How to dx?
Immune mediated; circulating IgG and IgM to penicillin derivatives
Bronchoalveolar washing and transbronchial biopsy
Mainly clinical - epidemiological and seasonal setting
Postcoital voiding - increased intake of cranberry juice

3. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

4. 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.
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Every 3-4 hours to determine appropritate time to start HAART
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

5. How to tx pcp?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
When cd4 count falls below 200. 2p in pcp =200
Upper lobes; any fibrosis in this area suggestive of latent TB
Aortic valve; endocardiits of AR p/w AV block and LBBB

6. 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)
PML; focal neurological deficit like MM; no specific tx; regress with HAART
<500 copies/ml
Reddish orange discoloration of urine - feces - sweat - tears - sputum

7. after exposure of HIV when antibody testing is performed?
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Immune mediated; circulating IgG and IgM to penicillin derivatives
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
ELISA; initial visit - 6 - 12 and 24 weeks;

8. How to dx cryptococal meninggits
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Acyclovir

9. which heart valve is closer to ventricular conduction system/
ELISA; initial visit - 6 - 12 and 24 weeks;
Every 3-4 hours to determine appropritate time to start HAART
Aortic valve; endocardiits of AR p/w AV block and LBBB
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

10. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Pregnacy - urologic procedure - hip arthoplastu
HBIG hep B immunoglobulin
Rifampin600mg q12. or cipro
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

11. How long abx is given in pseudomonas infection?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
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 RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Pt who have been treated before for latent TB

12. How to dx progressive multifocal leukoencephalopathy
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
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
Upper lobes; any fibrosis in this area suggestive of latent TB

13. What is tx for herpes zoster
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
<5000 copies/ml
Acyclovir
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

14. hypertriglyceridemia in HIV
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Oropharyngeal secretions; hence named as kissing disease
Either TB or aspergillosis
Pt who have been treated before for latent TB

15. how CMV presents in immunocompromised patients
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Clostridium perfringens after penetrative injuries/wounds
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

16. when not to give INH therapy if ppd positive and patient asyptomatic
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Pegylated interferon and lamivudine
Pt who have been treated before for latent TB
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

17. What is the Tx of cryptococcal meninngitis
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Pegylated interferon and lamivudine
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

18. infiltrate in upper lobe of lung?
Every 3-4 hours to determine appropritate time to start HAART
Monospot test which screen heteropile ab that agglutinate horse rbc
Either TB or aspergillosis
Clostridium perfringens after penetrative injuries/wounds

19. pneumococcal vaccine indication?
High risk 19-64; 1-2 dose - above 65; one dose
Acyclovir
Vaccine titer >10mU/ml
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

20. When to give prophylaxis against MAC
Rifampin600mg q12. or cipro
Every 3-4 hours to determine appropritate time to start HAART
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

21. what would be viral load after 4 weeks
If a sample is ELISA positive - it is tested fro western blot for confirmation
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
<5000 copies/ml
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

22. after recent exposure - negative ELISA - How to confirm?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
High risk 19-64; 1-2 dose - above 65; one dose
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

23. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Monospot test which screen heteropile ab that agglutinate horse rbc

24. When to tx influenza with antiviral therapy?
Mainly clinical - epidemiological and seasonal setting
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
Cd4 count
Need lumbar puncture to relieve pressure; they have high opening pressure >350

25. acute onset +rusty sputum
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Aortic valve; endocardiits of AR p/w AV block and LBBB

26. 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
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

27. How to tx TSS?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Bronchoalveolar washing and transbronchial biopsy
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
<500 copies/ml

28. How to dx adequate response to HBV vaccine
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Vaccine titer >10mU/ml
Postcoital voiding - increased intake of cranberry juice
ELISA; initial visit - 6 - 12 and 24 weeks;

29. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
If a sample is ELISA positive - it is tested fro western blot for confirmation
When cd4 count falls below 200. 2p in pcp =200
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

30. gas gangrene
High risk 19-64; 1-2 dose - above 65; one dose
Ampicillin-sublactam; most bites contain eikenella
Voriconazol. mycetoma-surgical removal
Clostridium perfringens after penetrative injuries/wounds

31. How to dx bacterial meningitis from CSF study?

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32. how HAART therapy affects HIV viral loads?
Within 6 months viral load will be <50
Clostridium perfringens after penetrative injuries/wounds
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
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

33. What is the pathophysiology of Meningococcal meningitis?
HIV viral load
Non pregnant premanopausal - elderly - dm - sci - chronic foley
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
When cd4 count falls below 200. 2p in pcp =200

34. 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
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Monospot test which screen heteropile ab that agglutinate horse rbc
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

35. Tx of choice for human bites
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
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Ampicillin-sublactam; most bites contain eikenella
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

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

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37. causative organisms of uti
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Similar pathophysiology as ITP - tx zidovudine

38. When not to tx asymptomatic bacteriura?
ELISA; initial visit - 6 - 12 and 24 weeks;
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Bronchoalveolar washing and transbronchial biopsy

39. low grade fever - maculopapular rash - lymphadenopathy
AA gradient >35 or Po2 <70
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Need lumbar puncture to relieve pressure; they have high opening pressure >350
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

40. How to tx chronic hep B
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
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Pegylated interferon and lamivudine

41. thrombocytopenia in HIV
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Similar pathophysiology as ITP - tx zidovudine
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

42. what parameters increases risk of neurosyphilis in HIV patient
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
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.
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

43. acute febrile reaction develops after starting penicilin tx to syphilis patient
Postcoital voiding - increased intake of cranberry juice
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

44. wisconsin - missisipi - ohio
Oropharyngeal secretions; hence named as kissing disease
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Blastomycosis
Bronchoalveolar washing and transbronchial biopsy

45. How to confirm chlamydia infection?
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
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.

46. dame that has already occurred
HIV viral load
Cd4 count
Viral load and CD4 count
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

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

48. What is used for prophylaxis against meningo..meningitis?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Voriconazol. mycetoma-surgical removal
Rifampin600mg q12. or cipro
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

49. systolic HTN in elderly
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
If a sample is ELISA positive - it is tested fro western blot for confirmation
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

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
6-12 weeks
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole