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. How to dx IM?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
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
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

2. INH
Acyclovir
Do EBV antibody test
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
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

3. How long abx is given in pseudomonas infection?
Others lesions are ring enhancing and have mass effect while PML don't
Viral load and CD4 count
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Within 6 months viral load will be <50

4. foot infections in DM
Oropharyngeal secretions; hence named as kissing disease
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Within 6 months viral load will be <50

5. What is the pathophysiology of Meningococcal meningitis?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
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
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

6. wisconsin - missisipi - ohio
Blastomycosis
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

7. acute febrile reaction develops after starting penicilin tx to syphilis patient
Acyclovir
Aortic valve; endocardiits of AR p/w AV block and LBBB
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

8. How to dx?
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Mainly clinical - epidemiological and seasonal setting
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

9. low grade fever - maculopapular rash - lymphadenopathy
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Ampicillin-sublactam; most bites contain eikenella
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

10. gas gangrene
Clostridium perfringens after penetrative injuries/wounds
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Reddish orange discoloration of urine - feces - sweat - tears - sputum
HBIG hep B immunoglobulin

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

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183

12. What is the mch of ampicillin induced rash in IM
Within 6 months viral load will be <50
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Vaccine titer >10mU/ml
Immune mediated; circulating IgG and IgM to penicillin derivatives

13. How to confirm dx if pcp?
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Bronchoalveolar washing and transbronchial biopsy
ELISA and western blot of synovial fluid.

14. When to tx influenza with antiviral therapy?
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
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
Aortic valve; endocardiits of AR p/w AV block and LBBB
When cd4 count falls below 200. 2p in pcp =200

15. What is tetanus - diptheria - pertusis recommendation?
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Td every 10 years - tdap once before 65 and after 65
Ampicillin-sublactam; most bites contain eikenella
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

16. What is difference between uti relapse versus recurrence?
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
Every 3-4 hours to determine appropritate time to start HAART
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
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?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
AA gradient >35 or Po2 <70
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
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

18. 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
If a sample is ELISA positive - it is tested fro western blot for confirmation
Bronchoalveolar washing and transbronchial biopsy
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

19. 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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
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
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

20. pathophysiology of toxic shock syndrom?
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.
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
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

21. How long we tx chronic prostatis?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
6-12 weeks
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
Oropharyngeal secretions; hence named as kissing disease

22. When not to tx asymptomatic bacteriura?
Mainly clinical - epidemiological and seasonal setting
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Non pregnant premanopausal - elderly - dm - sci - chronic foley

23. HIV patient having fat deposition on back of neck and abdomen - like cushing
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
PML; focal neurological deficit like MM; no specific tx; regress with HAART

24. worsening of TB after starting HAART in HIV
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Aortic valve; endocardiits of AR p/w AV block and LBBB

25. 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
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Do EBV antibody test
Others lesions are ring enhancing and have mass effect while PML don't

26. What is the Tx of STD uretheritis?
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
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
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
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. How to differentiate gonococcal and nongonoccal urethritis?
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
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.
Pregnacy - urologic procedure - hip arthoplastu
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

28. What is characteristic for dx of rocky mountain spotted fever?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Vaccine titer >10mU/ml
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Mainly clinical - epidemiological and seasonal setting

29. Tx of choice for human bites
Ampicillin-sublactam; most bites contain eikenella
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
Oropharyngeal secretions; hence named as kissing disease
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

30. 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
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Mainly clinical - epidemiological and seasonal setting
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

31. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
ELISA and western blot of synovial fluid.
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

32. pneumococcal vaccine indication?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Similar pathophysiology as ITP - tx zidovudine
High risk 19-64; 1-2 dose - above 65; one dose
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

33. dame that has already occurred
Vaccine titer >10mU/ml
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Cd4 count
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

34. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Td every 10 years - tdap once before 65 and after 65
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Non pregnant premanopausal - elderly - dm - sci - chronic foley

35. How to dx bacterial meningitis from CSF study?

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183

36. thrombocytopenia in HIV
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
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Similar pathophysiology as ITP - tx zidovudine

37. What is tx for herpes zoster
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
When cd4 count falls below 200. 2p in pcp =200
Every 3-4 hours to determine appropritate time to start HAART
Acyclovir

38. how CMV presents in immunocompromised patients
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
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.
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

39. How to confirm chlamydia infection?
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
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
PML; focal neurological deficit like MM; no specific tx; regress with HAART

40. What is the classic signs of nec fasc?
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 with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
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

41. clinical manifestation of mucomycosis
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
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

42. when western blot is done for HIV testing
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
If a sample is ELISA positive - it is tested fro western blot for confirmation
Acyclovir
When cd4 count falls below 200. 2p in pcp =200

43. What are indicators for progression of HIV
ELISA and western blot of synovial fluid.
Immune mediated; circulating IgG and IgM to penicillin derivatives
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Viral load and CD4 count

44. can HIV transmitted through human bite?
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
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

45. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
ELISA; initial visit - 6 - 12 and 24 weeks;
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Cd4 count
Pregnacy - urologic procedure - hip arthoplastu

46. 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.
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Either TB or aspergillosis

47. How to dx lyme arthritis?
Postcoital voiding - increased intake of cranberry juice
ELISA and western blot of synovial fluid.
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
When cd4 count falls below 200. 2p in pcp =200

48. after exposure of HIV when antibody testing is performed?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Immune mediated; circulating IgG and IgM to penicillin derivatives
<500 copies/ml
ELISA; initial visit - 6 - 12 and 24 weeks;

49. How to tx pcp?
Acyclovir
Every 3-4 hours to determine appropritate time to start HAART
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

50. How to tx IM?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
HBIG hep B immunoglobulin
Aortic valve; endocardiits of AR p/w AV block and LBBB
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)