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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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1. How long abx is given in pseudomonas infection?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
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

2. foot infections in DM
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.
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

3. 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
Either TB or aspergillosis
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Vaccine titer >10mU/ml

4. How to dx bacterial meningitis from CSF study?

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5. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
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
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Oropharyngeal secretions; hence named as kissing disease

6. how CMV presents in immunocompromised patients
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Aortic valve; endocardiits of AR p/w AV block and LBBB
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

7. What is fatal consequence of RMSF?
<5000 copies/ml
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Td every 10 years - tdap once before 65 and after 65
Acyclovir

8. What is tx for herpes zoster
HIV viral load
Acyclovir
Monospot test which screen heteropile ab that agglutinate horse rbc
Postcoital voiding - increased intake of cranberry juice

9. what parameters increases risk of neurosyphilis in HIV patient
Every 3-4 hours to determine appropritate time to start HAART
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.
Vaccine titer >10mU/ml
<500 copies/ml

10. What is the mch of ampicillin induced rash in IM
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Immune mediated; circulating IgG and IgM to penicillin derivatives

11. What is the indication of corticosteroid in pcp infection?
AA gradient >35 or Po2 <70
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Td every 10 years - tdap once before 65 and after 65
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

12. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
Others lesions are ring enhancing and have mass effect while PML don't
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Within 6 months viral load will be <50
PML; focal neurological deficit like MM; no specific tx; regress with HAART

13. when western blot is done for HIV testing
Td every 10 years - tdap once before 65 and after 65
If a sample is ELISA positive - it is tested fro western blot for confirmation
Non pregnant premanopausal - elderly - dm - sci - chronic foley
PML; focal neurological deficit like MM; no specific tx; regress with HAART

14. How to tx TSS?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Oropharyngeal secretions; hence named as kissing disease

15. gas gangrene
Clostridium perfringens after penetrative injuries/wounds
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
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

16. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
HBIG hep B immunoglobulin
If a sample is ELISA positive - it is tested fro western blot for confirmation
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
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

17. hypertension in children
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
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

18. How often viral load is monitored after HAART?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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
Pregnacy - urologic procedure - hip arthoplastu
When cd4 count falls below 200. 2p in pcp =200

19. antibiotic with good prostate penetration?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
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

20. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Td every 10 years - tdap once before 65 and after 65
HBIG hep B immunoglobulin
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

21. What are the subjective /objective measure of encephalopathy?
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Pregnacy - urologic procedure - hip arthoplastu
Within 6 months viral load will be <50
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

22. How to differentiate gonococcal and nongonoccal urethritis?
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
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
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

23. causative organisms of uti
HIV viral load
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
HBIG hep B immunoglobulin
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

24. How often HIV postiive patients CD4 count needs to be evaluated?
Do EBV antibody test
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Every 3-4 hours to determine appropritate time to start HAART
Monospot test which screen heteropile ab that agglutinate horse rbc

25. INH
PML; focal neurological deficit like MM; no specific tx; regress with HAART
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.
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

26. acute febrile reaction develops after starting penicilin tx to syphilis patient
Cd4 count
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
AA gradient >35 or Po2 <70

27. what would be viral load after 2-4m of HAART?
<500 copies/ml
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

28. When not to tx asymptomatic bacteriura?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Cd4 count
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
<500 copies/ml

29. How long we tx chronic prostatis?
6-12 weeks
Upper lobes; any fibrosis in this area suggestive of latent TB
Others lesions are ring enhancing and have mass effect while PML don't
Clostridium perfringens after penetrative injuries/wounds

30. How to dx cryptococal meninggits
Pregnacy - urologic procedure - hip arthoplastu
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
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

31. after recent exposure - negative ELISA - How to confirm?
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
HBIG hep B immunoglobulin
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

32. What is lag time to develop lyme arthritis after exposure to vector
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Vaccine titer >10mU/ml
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

33. wisconsin - missisipi - ohio
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Blastomycosis
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.

34. How to give postexposure prophylaxis for HIV
Cd4 count
ELISA; initial visit - 6 - 12 and 24 weeks;
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

35. How to tx pseudomonas?
Acyclovir
<5000 copies/ml
Cd4 count
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

36. pathophysiology of toxic shock syndrom?
AA gradient >35 or Po2 <70
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Pt who have been treated before for latent TB
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

37. How to tx pcp?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Pt who have been treated before for latent TB
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
HBIG hep B immunoglobulin

38. What is the Tx of cryptococcal meninngitis
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Postcoital voiding - increased intake of cranberry juice

39. How to dx adequate response to HBV vaccine
Vaccine titer >10mU/ml
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Every 3-4 hours to determine appropritate time to start HAART
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

40. What is used for prophylaxis against meningo..meningitis?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Rifampin600mg q12. or cipro
Pregnacy - urologic procedure - hip arthoplastu

41. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Need lumbar puncture to relieve pressure; they have high opening pressure >350
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
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Viral load and CD4 count

42. after exposure of HIV when antibody testing is performed?
ELISA; initial visit - 6 - 12 and 24 weeks;
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Mainly clinical - epidemiological and seasonal setting
Bronchoalveolar washing and transbronchial biopsy

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

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44. What is difference between uti relapse versus recurrence?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Rifampin600mg q12. or cipro
Pt who have been treated before for 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

45. How to tx chronic hep B
Pegylated interferon and lamivudine
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
When cd4 count falls below 200. 2p in pcp =200

46. What is the prognosis of lyme arthritis?
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
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

47. What is the Tx of STD uretheritis?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Monospot test which screen heteropile ab that agglutinate horse rbc
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
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

48. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Every 3-4 hours to determine appropritate time to start HAART
Aortic valve; endocardiits of AR p/w AV block and LBBB
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
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

49. clinical manifestation of mucomycosis
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
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
Oropharyngeal secretions; hence named as kissing disease
Viral load and CD4 count

50. acute onset +rusty sputum
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
ELISA; initial visit - 6 - 12 and 24 weeks;
Pt who have been treated before for latent TB
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol