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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. When to give prophylaxis against MAC
AA gradient >35 or Po2 <70
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
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

2. How to dx cryptococal meninggits
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Upper lobes; any fibrosis in this area suggestive of latent TB
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

3. gas gangrene
High risk 19-64; 1-2 dose - above 65; one dose
Blastomycosis
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Clostridium perfringens after penetrative injuries/wounds

4. pathophysiology of toxic shock syndrom?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Others lesions are ring enhancing and have mass effect while PML don't
6-12 weeks
Clostridium perfringens after penetrative injuries/wounds

5. drugs work well on hypertriglyceridia?
Need lumbar puncture to relieve pressure; they have high opening pressure >350
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
Mainly clinical - epidemiological and seasonal setting
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

6. How long we tx chronic prostatis?
High risk 19-64; 1-2 dose - above 65; one dose
6-12 weeks
If a sample is ELISA positive - it is tested fro western blot for confirmation
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

7. What is the Tx of cryptococcal meninngitis
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
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Immune mediated; circulating IgG and IgM to penicillin derivatives

8. How to tx pseudomonas?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Cd4 count

9. What is used for prophylaxis against meningo..meningitis?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Rifampin600mg q12. or cipro
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Postcoital voiding - increased intake of cranberry juice

10. clinical manifestation of mucomycosis
Vaccine titer >10mU/ml
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
6-12 weeks

11. How to dx IM?
Do EBV antibody test
6-12 weeks
Voriconazol. mycetoma-surgical removal
Monospot test which screen heteropile ab that agglutinate horse rbc

12. How to tx pcp?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Postcoital voiding - increased intake of cranberry juice
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Either TB or aspergillosis

13. What is the indication of corticosteroid in pcp infection?
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Aortic valve; endocardiits of AR p/w AV block and LBBB
AA gradient >35 or Po2 <70
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

14. INH
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
HBIG hep B immunoglobulin
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
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

15. rifampin
Voriconazol. mycetoma-surgical removal
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Reddish orange discoloration of urine - feces - sweat - tears - sputum

16. hypertension in children
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
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
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

17. What is the pathophysiology of Meningococcal meningitis?
Immune mediated; circulating IgG and IgM to penicillin derivatives
Within 6 months viral load will be <50
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

18. after exposure of HIV when antibody testing is performed?
Either TB or aspergillosis
Clostridium perfringens after penetrative injuries/wounds
ELISA; initial visit - 6 - 12 and 24 weeks;
Monospot test which screen heteropile ab that agglutinate horse rbc

19. How to confirm dx if pcp?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
<5000 copies/ml
Bronchoalveolar washing and transbronchial biopsy
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

20. How to tx chronic hep B
Td every 10 years - tdap once before 65 and after 65
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Pegylated interferon and lamivudine

21. what would be viral load after 2-4m of HAART?
<500 copies/ml
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
ELISA; initial visit - 6 - 12 and 24 weeks;

22. What are indicators for progression of HIV
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Do EBV antibody test
Viral load and CD4 count

23. acute febrile reaction develops after starting penicilin tx to syphilis patient
6-12 weeks
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

24. When to give abx to prevent recurrent uti
Aortic valve; endocardiits of AR p/w AV block and LBBB
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
Monospot test which screen heteropile ab that agglutinate horse rbc
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

25. How to dx bacterial meningitis from CSF study?

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26. when western blot is done for HIV testing
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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
Every 3-4 hours to determine appropritate time to start HAART
If a sample is ELISA positive - it is tested fro western blot for confirmation

27. What is the mch of ampicillin induced rash in IM
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Immune mediated; circulating IgG and IgM to penicillin derivatives
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

28. When to tx asymptomatic bacteriurea >100 -000?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Pregnacy - urologic procedure - hip arthoplastu
Every 3-4 hours to determine appropritate time to start HAART

29. aspergillosis
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
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.
Voriconazol. mycetoma-surgical removal
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

30. When not to tx asymptomatic bacteriura?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Vaccine titer >10mU/ml
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

31. what parameters increases risk of neurosyphilis in HIV patient
Viral load and CD4 count
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.
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

32. wisconsin - missisipi - ohio
Blastomycosis
If a sample is ELISA positive - it is tested fro western blot for confirmation
Mainly clinical - epidemiological and seasonal setting
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

33. How often HIV postiive patients CD4 count needs to be evaluated?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Td every 10 years - tdap once before 65 and after 65
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.
Every 3-4 hours to determine appropritate time to start HAART

34. when not to give INH therapy if ppd positive and patient asyptomatic
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Every 3-4 hours to determine appropritate time to start HAART
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Pt who have been treated before for latent TB

35. when we see echym gangrenosum?
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
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
PML; focal neurological deficit like MM; no specific tx; regress with HAART

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

37. What are the behavioral interventions decrease the risk of UTI
Ampicillin-sublactam; most bites contain eikenella
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Postcoital voiding - increased intake of cranberry juice
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

38. hypertriglyceridemia in HIV
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
If a sample is ELISA positive - it is tested fro western blot for confirmation
Mainly clinical - epidemiological and seasonal setting
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

39. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Blastomycosis
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

40. 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
Vaccine titer >10mU/ml
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Voriconazol. mycetoma-surgical removal

41. low grade fever - maculopapular rash - lymphadenopathy
Mainly clinical - epidemiological and seasonal setting
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

42. systolic HTN in elderly
If a sample is ELISA positive - it is tested fro western blot for confirmation
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >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
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

43. What is lag time to develop lyme arthritis after exposure to vector
ELISA and western blot of synovial fluid.
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Mainly clinical - epidemiological and seasonal setting

44. What is the classic signs of nec fasc?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Mainly clinical - epidemiological and seasonal setting
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
ELISA and western blot of synovial fluid.

45. What is the criteria for Spontaneous bact peritonitis
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
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Need lumbar puncture to relieve pressure; they have high opening pressure >350

46. how CMV presents in immunocompromised patients
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
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
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

47. How to differentiate gonococcal and nongonoccal urethritis?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
AA gradient >35 or Po2 <70
HIV viral load
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

48. where TB normally affects
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Upper lobes; any fibrosis in this area suggestive of latent TB
Acyclovir

49. When to tx influenza with antiviral therapy?
Within 6 months viral load will be <50
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
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

50. how im is transmitted?
Blastomycosis
Oropharyngeal secretions; hence named as kissing disease
Aortic valve; endocardiits of AR p/w AV block and LBBB
Monospot test which screen heteropile ab that agglutinate horse rbc