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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 HAART therapy affects HIV viral loads?
Within 6 months viral load will be <50
Bronchoalveolar washing and transbronchial biopsy
Others lesions are ring enhancing and have mass effect while PML don't
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

2. What is used for prophylaxis against meningo..meningitis?
Rifampin600mg q12. or cipro
Pregnacy - urologic procedure - hip arthoplastu
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.
<500 copies/ml

3. What are the subjective /objective measure of encephalopathy?
Pegylated interferon and lamivudine
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

4. How to dx progressive multifocal leukoencephalopathy
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

5. 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
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Every 3-4 hours to determine appropritate time to start HAART
Clostridium perfringens after penetrative injuries/wounds

6. how CMV presents in immunocompromised patients
HIV viral load
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

7. What is difference between uti relapse versus recurrence?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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
Aortic valve; endocardiits of AR p/w AV block and LBBB

8. antibiotic with good prostate penetration?
Ampicillin-sublactam; most bites contain eikenella
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Blastomycosis

9. How to differentiate different types of necrotizing fascitis?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
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
6-12 weeks
PML; focal neurological deficit like MM; no specific tx; regress with HAART

10. How to confirm dx if pcp?
Immune mediated; circulating IgG and IgM to penicillin derivatives
Postcoital voiding - increased intake of cranberry juice
Bronchoalveolar washing and transbronchial biopsy
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

11. when western blot is done for HIV testing
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Bronchoalveolar washing and transbronchial biopsy
Rifampin600mg q12. or cipro
If a sample is ELISA positive - it is tested fro western blot for confirmation

12. What is fatal consequence of RMSF?
Vaccine titer >10mU/ml
ELISA; initial visit - 6 - 12 and 24 weeks;
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

13. drugs work well on hypertriglyceridia?
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Upper lobes; any fibrosis in this area suggestive of latent TB

14. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Cd4 count
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Voriconazol. mycetoma-surgical removal
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

15. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Within 6 months viral load will be <50
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

16. foot infections in DM
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Oropharyngeal secretions; hence named as kissing disease
Acyclovir
Reddish orange discoloration of urine - feces - sweat - tears - sputum

17. low grade fever - maculopapular rash - lymphadenopathy
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
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 syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

18. what would be viral load after 4 weeks
<5000 copies/ml
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
6-12 weeks
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

19. reddish colored papules with central umbilication in HIV or immunocompromised 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.
Immune mediated; circulating IgG and IgM to penicillin derivatives
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
Do EBV antibody test

20. What is the classic signs of nec fasc?
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
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

21. what if monospot test is neg in IM?
ELISA and western blot of synovial fluid.
Do EBV antibody test
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

22. what parameters increases risk of neurosyphilis in HIV patient
Postcoital voiding - increased intake of cranberry juice
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.
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
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

23. gas gangrene
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Clostridium perfringens after penetrative injuries/wounds
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Need lumbar puncture to relieve pressure; they have high opening pressure >350

24. worsening of TB after starting HAART in HIV
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

25. How to tx pcp?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
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
Postcoital voiding - increased intake of cranberry juice
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

26. HIV patient having fat deposition on back of neck and abdomen - like cushing
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Bronchoalveolar washing and transbronchial biopsy
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.

27. When to give prophylaxis against MAC
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
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

28. pneumococcal vaccine indication?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
High risk 19-64; 1-2 dose - above 65; one dose
Upper lobes; any fibrosis in this area suggestive of latent TB

29. What are indicators for progression of HIV
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
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Viral load and CD4 count

30. How to dx?
Mainly clinical - epidemiological and seasonal setting
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Monospot test which screen heteropile ab that agglutinate horse rbc

31. where TB normally affects
Monospot test which screen heteropile ab that agglutinate horse rbc
Every 3-4 hours to determine appropritate time to start HAART
Upper lobes; any fibrosis in this area suggestive of latent TB
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

32. What is tetanus - diptheria - pertusis recommendation?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Td every 10 years - tdap once before 65 and after 65
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

33. When to tx influenza with antiviral therapy?
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
<500 copies/ml
If a sample is ELISA positive - it is tested fro western blot for confirmation
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

34. How to dx IM?
Every 3-4 hours to determine appropritate time to start HAART
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Mainly clinical - epidemiological and seasonal setting
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

35. What is the Tx of cryptococcal meninngitis
AA gradient >35 or Po2 <70
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

36. What is the mch of ampicillin induced rash in IM
Immune mediated; circulating IgG and IgM to penicillin derivatives
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 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 - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

37. how im is transmitted?
Acyclovir
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Oropharyngeal secretions; hence named as kissing disease
Td every 10 years - tdap once before 65 and after 65

38. When not to tx asymptomatic bacteriura?
Pegylated interferon and lamivudine
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
Non pregnant premanopausal - elderly - dm - sci - chronic foley
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

39. What is the prognosis of lyme arthritis?
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
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

40. rifampin
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Acyclovir

41. How to give postexposure prophylaxis for HIV
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; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

42. acute onset +rusty sputum
6-12 weeks
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
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

43. can HIV transmitted through human bite?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Do EBV antibody test
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
PML; focal neurological deficit like MM; no specific tx; regress with HAART

44. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
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

45. when HIV patient develop pcp?
Reddish orange discoloration of urine - feces - sweat - tears - sputum
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
When cd4 count falls below 200. 2p in pcp =200
Cd4 count

46. How to differentiat PML from toxoxplasmosis - cns lymphoma adn brain abscess

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47. What is tx for herpes zoster
Acyclovir
Mainly clinical - epidemiological and seasonal setting
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
HIV viral load

48. How to dx cryptococal meninggits
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
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
HBIG hep B immunoglobulin

49. How often HIV postiive patients CD4 count needs to be evaluated?
Every 3-4 hours to determine appropritate time to start HAART
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Immune mediated; circulating IgG and IgM to penicillin derivatives
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

50. thrombocytopenia in HIV
Similar pathophysiology as ITP - tx zidovudine
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
AA gradient >35 or Po2 <70
Within 6 months viral load will be <50