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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. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
ELISA and western blot of synovial fluid.
Postcoital voiding - increased intake of cranberry juice
HBIG hep B immunoglobulin
Monospot test which screen heteropile ab that agglutinate horse rbc

2. wisconsin - missisipi - ohio
Postcoital voiding - increased intake of cranberry juice
Blastomycosis
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

3. How to dx progressive multifocal leukoencephalopathy
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Pregnacy - urologic procedure - hip arthoplastu
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
6-12 weeks

4. How to tx TSS?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Similar pathophysiology as ITP - tx zidovudine

5. How to dx bacterial meningitis from CSF study?

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6. How to differentiate different types of necrotizing fascitis?
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
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
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

7. how HAART therapy affects HIV viral loads?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Either TB or aspergillosis
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Within 6 months viral load will be <50

8. drugs work well on hypertriglyceridia?
Td every 10 years - tdap once before 65 and after 65
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.

9. What is the prognosis of lyme arthritis?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
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
Either TB or aspergillosis

10. after exposure of HIV when antibody testing is performed?
ELISA; initial visit - 6 - 12 and 24 weeks;
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Rifampin600mg q12. or cipro
Within 6 months viral load will be <50

11. What is the mch of ampicillin induced rash in IM
Immune mediated; circulating IgG and IgM to penicillin derivatives
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
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

12. When to tx asymptomatic bacteriurea >100 -000?
If a sample is ELISA positive - it is tested fro western blot for confirmation
Pregnacy - urologic procedure - hip arthoplastu
AA gradient >35 or Po2 <70
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

13. Tx of choice for human bites
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
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Ampicillin-sublactam; most bites contain eikenella
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

14. damae that is about to occur?
HIV viral load
Postcoital voiding - increased intake of cranberry juice
Pegylated interferon and lamivudine
Monospot test which screen heteropile ab that agglutinate horse rbc

15. hypertension in children
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Viral load and CD4 count
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

16. what would be viral load after 2-4m of HAART?
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
Ampicillin-sublactam; most bites contain eikenella
Similar pathophysiology as ITP - tx zidovudine
<500 copies/ml

17. INH
ELISA; initial visit - 6 - 12 and 24 weeks;
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Pregnacy - urologic procedure - hip arthoplastu

18. 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
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
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
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

19. When to tx influenza with antiviral therapy?
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
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

20. What is the indication of corticosteroid in pcp infection?
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Similar pathophysiology as ITP - tx zidovudine
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
AA gradient >35 or Po2 <70

21. What are the subjective /objective measure of encephalopathy?
Aortic valve; endocardiits of AR p/w AV block and LBBB
<500 copies/ml
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Non pregnant premanopausal - elderly - dm - sci - chronic foley

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

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23. aspergillosis
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Voriconazol. mycetoma-surgical removal
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.

24. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
When cd4 count falls below 200. 2p in pcp =200
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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
HBIG hep B immunoglobulin

25. INH
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
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
Clostridium perfringens after penetrative injuries/wounds
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

26. acute onset +rusty sputum
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Td every 10 years - tdap once before 65 and after 65

27. How to give postexposure prophylaxis for HIV
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Ampicillin-sublactam; most bites contain eikenella
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

28. when not to give INH therapy if ppd positive and patient asyptomatic
Monospot test which screen heteropile ab that agglutinate horse rbc
Pt who have been treated before for latent TB
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Mainly clinical - epidemiological and seasonal setting

29. 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
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Blastomycosis

30. foot infections in DM
If a sample is ELISA positive - it is tested fro western blot for confirmation
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

31. How to dx IM?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
ELISA; initial visit - 6 - 12 and 24 weeks;
Do EBV antibody test
Monospot test which screen heteropile ab that agglutinate horse rbc

32. what parameters increases risk of neurosyphilis in HIV patient
Others lesions are ring enhancing and have mass effect while PML don't
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.
Immune mediated; circulating IgG and IgM to penicillin derivatives
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

33. low grade fever - maculopapular rash - lymphadenopathy
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Either TB or aspergillosis
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
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

34. rifampin
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
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

35. 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)
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Monospot test which screen heteropile ab that agglutinate horse rbc

36. systolic HTN in elderly
Acyclovir
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

37. after recent exposure - negative ELISA - How to confirm?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Acyclovir
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Pegylated interferon and lamivudine

38. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
6-12 weeks
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
AA gradient >35 or Po2 <70
Clostridium perfringens after penetrative injuries/wounds

39. what would be viral load after 4 weeks
Blastomycosis
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
<5000 copies/ml

40. How to tx pseudomonas?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Ampicillin-sublactam; most bites contain eikenella

41. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Oropharyngeal secretions; hence named as kissing disease
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

42. when HIV patient develop pcp?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Cd4 count
When cd4 count falls below 200. 2p in pcp =200

43. dame that has already occurred
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Rifampin600mg q12. or cipro
Cd4 count
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

44. How to confirm dx if pcp?
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
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
Bronchoalveolar washing and transbronchial biopsy

45. What is tetanus - diptheria - pertusis recommendation?
AA gradient >35 or Po2 <70
HBIG hep B immunoglobulin
Td every 10 years - tdap once before 65 and after 65
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

46. What is the classic signs of nec fasc?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
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
Td every 10 years - tdap once before 65 and after 65
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

47. how CMV presents in immunocompromised patients
Pt who have been treated before for latent TB
Acyclovir
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

48. antibiotic with good prostate penetration?
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
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
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

49. How often viral load is monitored after HAART?
Monospot test which screen heteropile ab that agglutinate horse rbc
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

50. How to dx?
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Mainly clinical - epidemiological and seasonal setting