Test your basic knowledge |

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. acute onset +rusty sputum
<5000 copies/ml
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
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
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

2. How to dx lyme arthritis?
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
6-12 weeks
ELISA and western blot of synovial fluid.

3. How often viral load is monitored after HAART?
Cd4 count
6-12 weeks
Rifampin600mg q12. or cipro
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

4. What is the indication of corticosteroid in pcp infection?
<5000 copies/ml
<500 copies/ml
AA gradient >35 or Po2 <70
ELISA; initial visit - 6 - 12 and 24 weeks;

5. What is the classic signs of nec fasc?
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
Every 3-4 hours to determine appropritate time to start HAART
Rifampin600mg q12. or cipro
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

6. How to tx pcp?
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
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

7. How to dx adequate response to HBV vaccine
Vaccine titer >10mU/ml
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Do EBV antibody test

8. reddish colored papules with central umbilication in HIV or immunocompromised patient
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Non pregnant premanopausal - elderly - dm - sci - chronic foley
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
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

9. rifampin
Blastomycosis
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Reddish orange discoloration of urine - feces - sweat - tears - sputum

10. What is difference between uti relapse versus recurrence?
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Others lesions are ring enhancing and have mass effect while PML don't
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

11. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Vaccine titer >10mU/ml
High risk 19-64; 1-2 dose - above 65; one dose
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

12. How to dx cryptococal meninggits
Bronchoalveolar washing and transbronchial biopsy
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

13. what would be viral load after 4 weeks
<5000 copies/ml
Vaccine titer >10mU/ml
Ampicillin-sublactam; most bites contain eikenella
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

14. INH
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Pregnacy - urologic procedure - hip arthoplastu
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

15. aspergillosis
Pt who have been treated before for latent TB
Monospot test which screen heteropile ab that agglutinate horse rbc
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Voriconazol. mycetoma-surgical removal

16. how HAART therapy affects HIV viral loads?
Pt who have been treated before for latent TB
Every 3-4 hours to determine appropritate time to start HAART
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Within 6 months viral load will be <50

17. How to tx IM?
Pegylated interferon and lamivudine
Monospot test which screen heteropile ab that agglutinate horse rbc
Within 6 months viral load will be <50
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

18. 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
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
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 RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

19. How to dx bacterial meningitis from CSF study?

20. What is fatal consequence of RMSF?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
HIV viral load
Ampicillin-sublactam; most bites contain eikenella
Either TB or aspergillosis

21. 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
Cd4 count
Clostridium perfringens after penetrative injuries/wounds
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

22. How to differentiate gonococcal and nongonoccal urethritis?
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
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 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.
Rifampin600mg q12. or cipro

23. hypertension in children
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Every 3-4 hours to determine appropritate time to start HAART

24. causative organisms of uti
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
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
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
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

25. after recent exposure - negative ELISA - How to confirm?
Oropharyngeal secretions; hence named as kissing disease
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

26. What is the Tx of STD uretheritis?
Cd4 count
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
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

27. When to tx influenza with antiviral therapy?
Monospot test which screen heteropile ab that agglutinate horse rbc
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
High risk 19-64; 1-2 dose - above 65; one dose
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

28. low grade fever - maculopapular rash - lymphadenopathy
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Either TB or aspergillosis
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

29. damae that is about to occur?
HIV viral load
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Immune mediated; circulating IgG and IgM to penicillin derivatives
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

30. what parameters increases risk of neurosyphilis in HIV patient
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.
Oropharyngeal secretions; hence named as kissing disease
<500 copies/ml
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

31. How long we tx chronic prostatis?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
6-12 weeks
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Blastomycosis

32. How to tx chronic hep B
Voriconazol. mycetoma-surgical removal
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
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Pegylated interferon and lamivudine

33. What is the Tx of cryptococcal meninngitis
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Every 3-4 hours to determine appropritate time to start HAART
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

34. can HIV transmitted through human bite?
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
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 present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
ELISA; initial visit - 6 - 12 and 24 weeks;

35. How to tx TSS?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Pregnacy - urologic procedure - hip arthoplastu

36. How often HIV postiive patients CD4 count needs to be evaluated?
Every 3-4 hours to determine appropritate time to start HAART
Cd4 count
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Monospot test which screen heteropile ab that agglutinate horse rbc

37. Tx of choice for human bites
AA gradient >35 or Po2 <70
Ampicillin-sublactam; most bites contain eikenella
Pegylated interferon and lamivudine
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

38. How to confirm dx if pcp?
Aortic valve; endocardiits of AR p/w AV block and LBBB
Postcoital voiding - increased intake of cranberry juice
Monospot test which screen heteropile ab that agglutinate horse rbc
Bronchoalveolar washing and transbronchial biopsy

39. How to dx IM?
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.
Bronchoalveolar washing and transbronchial biopsy
Immune mediated; circulating IgG and IgM to penicillin derivatives
Monospot test which screen heteropile ab that agglutinate horse rbc

40. What is characteristic for dx of rocky mountain spotted fever?
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
6-12 weeks
Need lumbar puncture to relieve pressure; they have high opening pressure >350
HBIG hep B immunoglobulin

41. how im is transmitted?
HIV viral load
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Acyclovir
Oropharyngeal secretions; hence named as kissing disease

42. When not to tx asymptomatic bacteriura?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
High risk 19-64; 1-2 dose - above 65; one dose
Non pregnant premanopausal - elderly - dm - sci - chronic foley
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

43. INH
Upper lobes; any fibrosis in this area suggestive of 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
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

44. What is the prognosis of lyme arthritis?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Pt who have been treated before for latent TB
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

45. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
Viral load and CD4 count
PML; focal neurological deficit like MM; no specific tx; regress with HAART
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
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

46. when not to give INH therapy if ppd positive and patient asyptomatic
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Pt who have been treated before for latent TB
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Aortic valve; endocardiits of AR p/w AV block and LBBB

47. What is lag time to develop lyme arthritis after exposure to vector
High risk 19-64; 1-2 dose - above 65; one dose
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Ampicillin-sublactam; most bites contain eikenella
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

48. after exposure of HIV when antibody testing is performed?
6-12 weeks
ELISA; initial visit - 6 - 12 and 24 weeks;
Immune mediated; circulating IgG and IgM to penicillin derivatives
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

49. What is the pathophysiology of Meningococcal meningitis?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Similar pathophysiology as ITP - tx zidovudine
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

50. How to tx pseudomonas?
Either TB or aspergillosis
Others lesions are ring enhancing and have mass effect while PML don't
<5000 copies/ml
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)