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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. causative organisms of uti
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Blastomycosis
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

2. when HIV patient develop pcp?
When cd4 count falls below 200. 2p in pcp =200
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
6-12 weeks

3. How to dx?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Rifampin600mg q12. or cipro
When cd4 count falls below 200. 2p in pcp =200
Mainly clinical - epidemiological and seasonal setting

4. How to dx cryptococal meninggits
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Cd4 count
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

5. How to dx bacterial meningitis from CSF study?

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6. How to tx IM?
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Oropharyngeal secretions; hence named as kissing disease
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

7. When to give abx to prevent recurrent uti
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
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.
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
HIV viral load

8. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Non pregnant premanopausal - elderly - dm - sci - chronic foley

9. When to tx influenza with antiviral therapy?
Do EBV antibody test
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
Pegylated interferon and lamivudine
ELISA and western blot of synovial fluid.

10. what would be viral load after 2-4m of HAART?
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
<500 copies/ml
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
Ampicillin-sublactam; most bites contain eikenella

11. What is the classic signs of nec fasc?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
ELISA and western blot of synovial fluid.
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.
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

12. How to dx adequate response to HBV vaccine
Vaccine titer >10mU/ml
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
If a sample is ELISA positive - it is tested fro western blot for confirmation

13. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Postcoital voiding - increased intake of cranberry juice
HBIG hep B immunoglobulin
Cd4 count
Either TB or aspergillosis

14. can HIV transmitted through human bite?
Mainly clinical - epidemiological and seasonal setting
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Cd4 count
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

15. How often HIV postiive patients CD4 count needs to be evaluated?
Every 3-4 hours to determine appropritate time to start HAART
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Non pregnant premanopausal - elderly - dm - sci - chronic foley
ELISA; initial visit - 6 - 12 and 24 weeks;

16. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Td every 10 years - tdap once before 65 and after 65
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Need lumbar puncture to relieve pressure; they have high opening pressure >350

17. How to confirm dx if pcp?
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Bronchoalveolar washing and transbronchial biopsy

18. chshould we tx IM with abx (ampicilin) if throat cx is positive?
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
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

19. dame that has already occurred
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Cd4 count
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Aortic valve; endocardiits of AR p/w AV block and LBBB

20. when we see echym gangrenosum?
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Either TB or aspergillosis
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
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

21. foot infections in DM
Voriconazol. mycetoma-surgical removal
Acyclovir
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Within 6 months viral load will be <50

22. What is the pathophysiology of Meningococcal meningitis?
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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. where TB normally affects
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Upper lobes; any fibrosis in this area suggestive of latent TB

24. What is tetanus - diptheria - pertusis recommendation?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Either TB or aspergillosis
Every 3-4 hours to determine appropritate time to start HAART
Td every 10 years - tdap once before 65 and after 65

25. How to confirm chlamydia infection?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Cd4 count
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

26. pneumococcal vaccine indication?
High risk 19-64; 1-2 dose - above 65; one dose
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
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
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

27. after recent exposure - negative ELISA - How to confirm?
Cd4 count
Every 3-4 hours to determine appropritate time to start HAART
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
AA gradient >35 or Po2 <70

28. how CMV presents in immunocompromised patients
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
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

29. low grade fever - maculopapular rash - lymphadenopathy
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Bronchoalveolar washing and transbronchial biopsy
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

30. thrombocytopenia in HIV
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Similar pathophysiology as ITP - tx zidovudine
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

31. What is the Tx of STD uretheritis?
Do EBV antibody test
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
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 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

32. damae that is about to occur?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
HIV viral load
HBIG hep B immunoglobulin

33. What is the criteria for Spontaneous bact peritonitis
Blastomycosis
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Bronchoalveolar washing and transbronchial biopsy
Upper lobes; any fibrosis in this area suggestive of latent TB

34. what parameters increases risk of neurosyphilis in HIV patient
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
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.
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
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

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

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36. When to give prophylaxis against MAC
Similar pathophysiology as ITP - tx zidovudine
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Oropharyngeal secretions; hence named as kissing disease

37. hypertension in children
Pt who have been treated before for latent TB
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
<5000 copies/ml

38. How to differentiate gonococcal and nongonoccal urethritis?
ELISA and western blot of synovial fluid.
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Cd4 count
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

39. What is the Tx of cryptococcal meninngitis
Blastomycosis
Upper lobes; any fibrosis in this area suggestive of latent TB
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

40. systolic HTN in elderly
When cd4 count falls below 200. 2p in pcp =200
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
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

41. What are indicators for progression of HIV
Aortic valve; endocardiits of AR p/w AV block and LBBB
Viral load and CD4 count
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

42. worsening of TB after starting HAART in HIV
Monospot test which screen heteropile ab that agglutinate horse rbc
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
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
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

43. drugs work well on hypertriglyceridia?
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Ampicillin-sublactam; most bites contain eikenella
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

44. how im is transmitted?
Oropharyngeal secretions; hence named as kissing disease
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Acyclovir
Others lesions are ring enhancing and have mass effect while PML don't

45. What are the behavioral interventions decrease the risk of UTI
Within 6 months viral load will be <50
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
Postcoital voiding - increased intake of cranberry juice
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

46. Tx of choice for human bites
<5000 copies/ml
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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
Ampicillin-sublactam; most bites contain eikenella

47. what if monospot test is neg in IM?
Viral load and CD4 count
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Do EBV antibody test

48. aspergillosis
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Voriconazol. mycetoma-surgical removal
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

49. What is the indication of corticosteroid in pcp infection?
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
HBIG hep B immunoglobulin
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
AA gradient >35 or Po2 <70

50. How often viral load is monitored after HAART?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Every 3-4 hours to determine appropritate time to start HAART
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
HBIG hep B immunoglobulin