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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. drugs work well on hypertriglyceridia?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
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

2. when HIV patient develop pcp?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
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
Td every 10 years - tdap once before 65 and after 65
When cd4 count falls below 200. 2p in pcp =200

3. How to dx progressive multifocal leukoencephalopathy
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
6-12 weeks
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

4. How long we tx chronic prostatis?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
<500 copies/ml
Postcoital voiding - increased intake of cranberry juice
6-12 weeks

5. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Need lumbar puncture to relieve pressure; they have high opening pressure >350
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
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

6. infiltrate in upper lobe of lung?
Either TB or aspergillosis
Bronchoalveolar washing and transbronchial biopsy
<5000 copies/ml
AA gradient >35 or Po2 <70

7. INH
Acyclovir
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Td every 10 years - tdap once before 65 and after 65

8. damae that is about to occur?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
HIV viral load

9. foot infections in DM
6-12 weeks
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

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

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11. What is tetanus - diptheria - pertusis recommendation?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Every 3-4 hours to determine appropritate time to start HAART
Td every 10 years - tdap once before 65 and after 65
6-12 weeks

12. when western blot is done for HIV testing
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
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
If a sample is ELISA positive - it is tested fro western blot for confirmation
Upper lobes; any fibrosis in this area suggestive of latent TB

13. clinical manifestation of mucomycosis
Postcoital voiding - increased intake of cranberry juice
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Viral load and CD4 count

14. What is the pathophysiology of Meningococcal meningitis?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Either TB or aspergillosis
Monospot test which screen heteropile ab that agglutinate horse rbc

15. what would be viral load after 2-4m of HAART?
Rifampin600mg q12. or cipro
When cd4 count falls below 200. 2p in pcp =200
<500 copies/ml
Every 3-4 hours to determine appropritate time to start HAART

16. How to confirm dx if pcp?
Bronchoalveolar washing and transbronchial biopsy
Vaccine titer >10mU/ml
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
If a sample is ELISA positive - it is tested fro western blot for confirmation

17. thrombocytopenia in HIV
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Similar pathophysiology as ITP - tx zidovudine
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
6-12 weeks

18. hypertriglyceridemia in HIV
Upper lobes; any fibrosis in this area suggestive of latent TB
Cd4 count
Aortic valve; endocardiits of AR p/w AV block and LBBB
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

19. What is difference between uti relapse versus recurrence?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Td every 10 years - tdap once before 65 and after 65
Cd4 count
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

20. When to give prophylaxis against MAC
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

21. How to tx chronic hep B
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Every 3-4 hours to determine appropritate time to start HAART
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Pegylated interferon and lamivudine

22. What is fatal consequence of RMSF?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Rifampin600mg q12. or cipro

23. aspergillosis
Oropharyngeal secretions; hence named as kissing disease
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Upper lobes; any fibrosis in this area suggestive of latent TB
Voriconazol. mycetoma-surgical removal

24. When to tx influenza with antiviral therapy?
Cd4 count
Upper lobes; any fibrosis in this area suggestive of latent TB
Aortic valve; endocardiits of AR p/w AV block and LBBB
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

25. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Viral load and CD4 count
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Upper lobes; any fibrosis in this area suggestive of latent TB

26. reddish colored papules with central umbilication in HIV or immunocompromised patient
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
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
HBIG hep B immunoglobulin

27. What is the classic signs of nec fasc?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
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
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
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

28. What is lag time to develop lyme arthritis after exposure to vector
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Viral load and CD4 count
6-12 weeks

29. after exposure of HIV when antibody testing is performed?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
<500 copies/ml
Rifampin600mg q12. or cipro
ELISA; initial visit - 6 - 12 and 24 weeks;

30. acute onset +rusty sputum
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
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
<5000 copies/ml
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

31. how im is transmitted?
Oropharyngeal secretions; hence named as kissing disease
Mainly clinical - epidemiological and seasonal setting
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

32. dame that has already occurred
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Within 6 months viral load will be <50
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
Cd4 count

33. What are the behavioral interventions decrease the risk of UTI
If a sample is ELISA positive - it is tested fro western blot for confirmation
Monospot test which screen heteropile ab that agglutinate horse rbc
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Postcoital voiding - increased intake of cranberry juice

34. What is the Tx of cryptococcal meninngitis
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
6-12 weeks
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

35. How to confirm chlamydia infection?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Mainly clinical - epidemiological and seasonal setting
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

36. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
HBIG hep B immunoglobulin
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
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

37. which heart valve is closer to ventricular conduction system/
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
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Aortic valve; endocardiits of AR p/w AV block and LBBB

38. How to dx?
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
Cd4 count
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Mainly clinical - epidemiological and seasonal setting

39. How to dx IM?
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Pegylated interferon and lamivudine
Monospot test which screen heteropile ab that agglutinate horse rbc
AA gradient >35 or Po2 <70

40. can HIV transmitted through human bite?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Every 3-4 hours to determine appropritate time to start HAART
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Upper lobes; any fibrosis in this area suggestive of latent TB

41. What are indicators for progression of HIV
ELISA; initial visit - 6 - 12 and 24 weeks;
<500 copies/ml
Viral load and CD4 count
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

42. How often viral load is monitored after HAART?
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
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

43. How to tx TSS?
Either TB or aspergillosis
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
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

44. How to dx IM?
Blastomycosis
If a sample is ELISA positive - it is tested fro western blot for confirmation
Pegylated interferon and lamivudine
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

45. when not to give INH therapy if ppd positive and patient asyptomatic
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Pt who have been treated before for latent TB

46. What is the criteria for Spontaneous bact peritonitis
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Blastomycosis
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

47. What is tx for herpes zoster
ELISA; initial visit - 6 - 12 and 24 weeks;
Vaccine titer >10mU/ml
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Acyclovir

48. low grade fever - maculopapular rash - lymphadenopathy
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Bronchoalveolar washing and transbronchial biopsy

49. When to give abx to prevent recurrent uti
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Monospot test which screen heteropile ab that agglutinate horse rbc
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

50. Tx of choice for human bites
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
Either TB or aspergillosis
Ampicillin-sublactam; most bites contain eikenella
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose