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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. What is fatal consequence of RMSF?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
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
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

2. When not to tx asymptomatic bacteriura?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Within 6 months viral load will be <50
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Non pregnant premanopausal - elderly - dm - sci - chronic foley

3. How often viral load is monitored after HAART?
Do EBV antibody test
AA gradient >35 or Po2 <70
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

4. how CMV presents in immunocompromised patients
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
High risk 19-64; 1-2 dose - above 65; one dose
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

5. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
6-12 weeks
Do EBV antibody test
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
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

6. What is the prognosis of lyme arthritis?
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Clostridium perfringens after penetrative injuries/wounds
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

7. antibiotic with good prostate penetration?
Bronchoalveolar washing and transbronchial biopsy
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
HIV viral load
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

8. hypertriglyceridemia in HIV
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
6-12 weeks
ELISA; initial visit - 6 - 12 and 24 weeks;
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

9. What is the Tx of cryptococcal meninngitis
Cd4 count
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
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
PML; focal neurological deficit like MM; no specific tx; regress with HAART

10. What is the Tx of STD uretheritis?
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Viral load and CD4 count
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

11. aspergillosis
Immune mediated; circulating IgG and IgM to penicillin derivatives
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
<5000 copies/ml
Voriconazol. mycetoma-surgical removal

12. How to tx pseudomonas?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Others lesions are ring enhancing and have mass effect while PML don't
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

13. How to dx lyme arthritis?
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
ELISA and western blot of synovial fluid.
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

14. How long we tx chronic prostatis?
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
6-12 weeks
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

15. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Oropharyngeal secretions; hence named as kissing disease
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

16. How to dx cryptococal meninggits
Do EBV antibody test
ELISA and western blot of synovial fluid.
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

17. after recent exposure - negative ELISA - How to confirm?
Acyclovir
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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.

18. What is tetanus - diptheria - pertusis recommendation?
Vaccine titer >10mU/ml
Td every 10 years - tdap once before 65 and after 65
Do EBV antibody test
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

19. gas gangrene
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
ELISA; initial visit - 6 - 12 and 24 weeks;
Clostridium perfringens after penetrative injuries/wounds
Within 6 months viral load will be <50

20. infiltrate in upper lobe of lung?
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
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
When cd4 count falls below 200. 2p in pcp =200
Either TB or aspergillosis

21. How to tx TSS?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

22. when not to give INH therapy if ppd positive and patient asyptomatic
Vaccine titer >10mU/ml
Pt who have been treated before for latent TB
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
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

23. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Reddish orange discoloration of urine - feces - sweat - tears - sputum
HBIG hep B immunoglobulin
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

24. 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)
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Pregnacy - urologic procedure - hip arthoplastu
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

25. How to dx progressive multifocal leukoencephalopathy
Cd4 count
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
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
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

26. rifampin
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
HIV viral load
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

27. how HAART therapy affects HIV viral loads?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Within 6 months viral load will be <50
Reddish orange discoloration of urine - feces - sweat - tears - sputum

28. How to give postexposure prophylaxis for HIV
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
<5000 copies/ml

29. foot infections in DM
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Clostridium perfringens after penetrative injuries/wounds
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

30. low grade fever - maculopapular rash - lymphadenopathy
Similar pathophysiology as ITP - tx zidovudine
High risk 19-64; 1-2 dose - above 65; one dose
Reddish orange discoloration of urine - feces - sweat - tears - sputum
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

31. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Postcoital voiding - increased intake of cranberry juice
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

32. 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.
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Monospot test which screen heteropile ab that agglutinate horse rbc
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

33. when we see echym gangrenosum?
Mainly clinical - epidemiological and seasonal setting
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Reddish orange discoloration of urine - feces - sweat - tears - sputum
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

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

35. 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.
Voriconazol. mycetoma-surgical removal
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Acyclovir

36. causative organisms of uti
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

37. what would be viral load after 2-4m of HAART?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Similar pathophysiology as ITP - tx zidovudine
<500 copies/ml
Pregnacy - urologic procedure - hip arthoplastu

38. wisconsin - missisipi - ohio
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Blastomycosis
High risk 19-64; 1-2 dose - above 65; one dose
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

39. where TB normally affects
<5000 copies/ml
Upper lobes; any fibrosis in this area suggestive of latent TB
Non pregnant premanopausal - elderly - dm - sci - chronic foley
ELISA; initial visit - 6 - 12 and 24 weeks;

40. dame that has already occurred
HBIG hep B immunoglobulin
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Cd4 count
ELISA; initial visit - 6 - 12 and 24 weeks;

41. which heart valve is closer to ventricular conduction system/
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Aortic valve; endocardiits of AR p/w AV block and LBBB
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

42. What is the indication of corticosteroid in pcp infection?
AA gradient >35 or Po2 <70
Rifampin600mg q12. or cipro
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
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

43. thrombocytopenia in HIV
Similar pathophysiology as ITP - tx zidovudine
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Bronchoalveolar washing and transbronchial biopsy
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

44. How to dx bacterial meningitis from CSF study?

45. When to give abx to prevent recurrent uti
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
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
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
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

46. What is tx for herpes zoster
Vaccine titer >10mU/ml
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Acyclovir
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

47. after exposure of HIV when antibody testing is performed?
Within 6 months viral load will be <50
ELISA; initial visit - 6 - 12 and 24 weeks;
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

48. how im is transmitted?
HIV viral load
Oropharyngeal secretions; hence named as kissing disease
If a sample is ELISA positive - it is tested fro western blot for confirmation
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

49. How to tx chronic hep B
Pegylated interferon and lamivudine
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Oropharyngeal secretions; hence named as kissing disease

50. What is used for prophylaxis against meningo..meningitis?
Rifampin600mg q12. or cipro
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Voriconazol. mycetoma-surgical removal
Others lesions are ring enhancing and have mass effect while PML don't