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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. HIV patient having fat deposition on back of neck and abdomen - like cushing
Immune mediated; circulating IgG and IgM to penicillin derivatives
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
If a sample is ELISA positive - it is tested fro western blot for confirmation
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

2. What is the Tx of cryptococcal meninngitis
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Do EBV antibody test
<500 copies/ml

3. thrombocytopenia in HIV
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Similar pathophysiology as ITP - tx zidovudine
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Non pregnant premanopausal - elderly - dm - sci - chronic foley

4. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
ELISA and western blot of synovial fluid.
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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

5. after recent exposure - negative ELISA - How to confirm?
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Either TB or aspergillosis

6. how im is transmitted?
Pegylated interferon and lamivudine
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
Oropharyngeal secretions; hence named as kissing disease
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

7. drugs work well on hypertriglyceridia?
Similar pathophysiology as ITP - tx zidovudine
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

8. When to tx asymptomatic bacteriurea >100 -000?
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Pregnacy - urologic procedure - hip arthoplastu
Upper lobes; any fibrosis in this area suggestive of latent TB
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

9. foot infections in DM
Pegylated interferon and lamivudine
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Voriconazol. mycetoma-surgical removal
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

10. what would be viral load after 2-4m of HAART?
Bronchoalveolar washing and transbronchial biopsy
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.
Pregnacy - urologic procedure - hip arthoplastu
<500 copies/ml

11. What is the Tx of STD uretheritis?
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
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

12. pathophysiology of toxic shock syndrom?
Voriconazol. mycetoma-surgical removal
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

13. How to dx IM?
6-12 weeks
ELISA; initial visit - 6 - 12 and 24 weeks;
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

14. dame that has already occurred
Others lesions are ring enhancing and have mass effect while PML don't
ELISA and western blot of synovial fluid.
Cd4 count
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

15. how CMV presents in immunocompromised patients
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
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
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

16. How to dx bacterial meningitis from CSF study?

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17. How long we tx chronic prostatis?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Viral load and CD4 count
Td every 10 years - tdap once before 65 and after 65
6-12 weeks

18. when we see echym gangrenosum?
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
ELISA; initial visit - 6 - 12 and 24 weeks;
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

19. 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
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
High risk 19-64; 1-2 dose - above 65; one dose

20. How long abx is given in pseudomonas infection?
Blastomycosis
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

21. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Viral load and CD4 count
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Acyclovir
Pregnacy - urologic procedure - hip arthoplastu

22. INH
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

23. INH
Acyclovir
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
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

24. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
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
HBIG hep B immunoglobulin
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

25. How to tx chronic hep B
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
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
Bronchoalveolar washing and transbronchial biopsy
Pegylated interferon and lamivudine

26. after exposure of HIV when antibody testing is performed?
Clostridium perfringens after penetrative injuries/wounds
ELISA; initial visit - 6 - 12 and 24 weeks;
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Viral load and CD4 count

27. How to dx?
Mainly clinical - epidemiological and seasonal setting
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Others lesions are ring enhancing and have mass effect while PML don't
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

28. when HIV patient develop pcp?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
When cd4 count falls below 200. 2p in pcp =200
Reddish orange discoloration of urine - feces - sweat - tears - sputum
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

29. which heart valve is closer to ventricular conduction system/
Every 3-4 hours to determine appropritate time to start HAART
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Aortic valve; endocardiits of AR p/w AV block and LBBB
6-12 weeks

30. chshould we tx IM with abx (ampicilin) if throat cx is positive?
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
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

31. What is tetanus - diptheria - pertusis recommendation?
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
High risk 19-64; 1-2 dose - above 65; one dose
Td every 10 years - tdap once before 65 and after 65

32. aspergillosis
Voriconazol. mycetoma-surgical removal
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
AA gradient >35 or Po2 <70
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

33. infiltrate in upper lobe of lung?
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
High risk 19-64; 1-2 dose - above 65; one dose
Either TB or aspergillosis
ELISA; initial visit - 6 - 12 and 24 weeks;

34. rifampin
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Reddish orange discoloration of urine - feces - sweat - tears - sputum
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
High risk 19-64; 1-2 dose - above 65; one dose

35. How to tx pseudomonas?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Td every 10 years - tdap once before 65 and after 65
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

36. How to confirm chlamydia infection?
HBIG hep B immunoglobulin
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

37. How to give postexposure prophylaxis for 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
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Similar pathophysiology as ITP - tx zidovudine

38. gas gangrene
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Clostridium perfringens after penetrative injuries/wounds

39. hypertriglyceridemia in HIV
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
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

40. How to tx TSS?
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
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
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

41. low grade fever - maculopapular rash - lymphadenopathy
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
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 RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
If a sample is ELISA positive - it is tested fro western blot for confirmation

42. How to differentiate gonococcal and nongonoccal urethritis?
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
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
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
Others lesions are ring enhancing and have mass effect while PML don't

43. How to dx progressive multifocal leukoencephalopathy
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Pt who have been treated before for latent TB
<500 copies/ml
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

44. What is fatal consequence of RMSF?
AA gradient >35 or Po2 <70
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

45. when not to give INH therapy if ppd positive and patient asyptomatic
Pt who have been treated before for latent TB
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
When cd4 count falls below 200. 2p in pcp =200
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

46. What are indicators for progression of HIV
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Viral load and CD4 count
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
HBIG hep B immunoglobulin

47. hypertension in children
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
<5000 copies/ml
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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. When to tx influenza with antiviral therapy?
Pegylated interferon and lamivudine
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
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

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

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50. What is tx for herpes zoster
Oropharyngeal secretions; hence named as kissing disease
Rifampin600mg q12. or cipro
HBIG hep B immunoglobulin
Acyclovir