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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. What is the prognosis of lyme arthritis?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
ELISA; initial visit - 6 - 12 and 24 weeks;
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

2. How to tx pcp?
Clostridium perfringens after penetrative injuries/wounds
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Upper lobes; any fibrosis in this area suggestive of latent TB

3. How to tx TSS?
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
Td every 10 years - tdap once before 65 and after 65
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

4. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
HBIG hep B immunoglobulin
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Upper lobes; any fibrosis in this area suggestive of latent TB
Reddish orange discoloration of urine - feces - sweat - tears - sputum

5. aspergillosis
Every 3-4 hours to determine appropritate time to start HAART
When cd4 count falls below 200. 2p in pcp =200
Voriconazol. mycetoma-surgical removal
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

6. How to confirm chlamydia infection?
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
Viral load and CD4 count
<500 copies/ml

7. what would be viral load after 4 weeks
Pregnacy - urologic procedure - hip arthoplastu
Immune mediated; circulating IgG and IgM to penicillin derivatives
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
<5000 copies/ml

8. When to tx asymptomatic bacteriurea >100 -000?
Pregnacy - urologic procedure - hip arthoplastu
Postcoital voiding - increased intake of cranberry juice
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

9. what would be viral load after 2-4m of HAART?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Voriconazol. mycetoma-surgical removal
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

10. acute onset +rusty sputum
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
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

11. wisconsin - missisipi - ohio
Blastomycosis
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
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
Monospot test which screen heteropile ab that agglutinate horse rbc

12. How to dx IM?
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Rifampin600mg q12. or cipro
Ampicillin-sublactam; most bites contain eikenella

13. How often viral load is monitored after HAART?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Acyclovir
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
PML; focal neurological deficit like MM; no specific tx; regress with HAART

14. causative organisms of uti
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Reddish orange discoloration of urine - feces - sweat - tears - sputum

15. foot infections in DM
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
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
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

16. 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
Oropharyngeal secretions; hence named as kissing disease
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

17. when HIV patient develop pcp?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
When cd4 count falls below 200. 2p in pcp =200

18. When not to tx asymptomatic bacteriura?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Non pregnant premanopausal - elderly - dm - sci - chronic foley

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

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20. can HIV transmitted through human bite?
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
Pt who have been treated before for latent TB
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

21. How to tx pseudomonas?
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
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
<500 copies/ml

22. when we see echym gangrenosum?
Pegylated interferon and lamivudine
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
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

23. What is the indication of corticosteroid in pcp infection?
Td every 10 years - tdap once before 65 and after 65
AA gradient >35 or Po2 <70
Reddish orange discoloration of urine - feces - sweat - tears - sputum
HBIG hep B immunoglobulin

24. How to tx IM?
AA gradient >35 or Po2 <70
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

25. hypertension in children
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

26. How to tx chronic hep B
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
Every 3-4 hours to determine appropritate time to start HAART
Similar pathophysiology as ITP - tx zidovudine
Pegylated interferon and lamivudine

27. 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
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
ELISA; initial visit - 6 - 12 and 24 weeks;

28. How to confirm dx if pcp?
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Bronchoalveolar washing and transbronchial biopsy
ELISA and western blot of synovial fluid.

29. What is the Tx of STD uretheritis?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
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
If a sample is ELISA positive - it is tested fro western blot for confirmation

30. What is used for prophylaxis against meningo..meningitis?
Rifampin600mg q12. or cipro
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
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

31. worsening of TB after starting HAART in HIV
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

32. How long abx is given in pseudomonas infection?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Do EBV antibody test
Monospot test which screen heteropile ab that agglutinate horse rbc
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

33. How to give postexposure prophylaxis for HIV
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

34. dame that has already occurred
Oropharyngeal secretions; hence named as kissing disease
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
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
Cd4 count

35. How long we tx chronic prostatis?
6-12 weeks
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

36. When to tx influenza with antiviral therapy?
AA gradient >35 or Po2 <70
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
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
When cd4 count falls below 200. 2p in pcp =200

37. infiltrate in upper lobe of lung?
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
Either TB or aspergillosis
Postcoital voiding - increased intake of cranberry juice

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

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39. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Clostridium perfringens after penetrative injuries/wounds
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
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Vaccine titer >10mU/ml

40. what parameters increases risk of neurosyphilis in HIV patient
<500 copies/ml
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.
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
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

41. What is tetanus - diptheria - pertusis recommendation?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Td every 10 years - tdap once before 65 and after 65
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Voriconazol. mycetoma-surgical removal

42. INH
If a sample is ELISA positive - it is tested fro western blot for confirmation
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
<5000 copies/ml

43. acute febrile reaction develops after starting penicilin tx to syphilis patient
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
Pregnacy - urologic procedure - hip arthoplastu
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

44. when not to give INH therapy if ppd positive and patient asyptomatic
Pt who have been treated before for latent TB
Vaccine titer >10mU/ml
ELISA and western blot of synovial fluid.
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

45. pneumococcal vaccine indication?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
High risk 19-64; 1-2 dose - above 65; one dose
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

46. how im is transmitted?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Every 3-4 hours to determine appropritate time to start HAART
Oropharyngeal secretions; hence named as kissing disease
Immune mediated; circulating IgG and IgM to penicillin derivatives

47. hypertriglyceridemia in HIV
Blastomycosis
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
<500 copies/ml

48. which heart valve is closer to ventricular conduction system/
Oropharyngeal secretions; hence named as kissing disease
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Aortic valve; endocardiits of AR p/w AV block and LBBB
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

49. INH
Upper lobes; any fibrosis in this area suggestive of latent TB
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.
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

50. rifampin
Reddish orange discoloration of urine - feces - sweat - tears - sputum
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
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)