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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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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Viral load and CD4 count
Voriconazol. mycetoma-surgical removal
HBIG hep B immunoglobulin

2. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Td every 10 years - tdap once before 65 and after 65
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

3. How to dx IM?
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.
Td every 10 years - tdap once before 65 and after 65
Oropharyngeal secretions; hence named as kissing disease
Monospot test which screen heteropile ab that agglutinate horse rbc

4. aspergillosis
Voriconazol. mycetoma-surgical removal
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
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

5. rifampin
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Reddish orange discoloration of urine - feces - sweat - tears - sputum

6. What is used for prophylaxis against meningo..meningitis?
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Rifampin600mg q12. or cipro
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

7. What is the classic signs of nec fasc?
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
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
Mainly clinical - epidemiological and seasonal setting

8. What is the pathophysiology of Meningococcal meningitis?
Acyclovir
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Vaccine titer >10mU/ml

9. How long we tx chronic prostatis?
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
6-12 weeks

10. which heart valve is closer to ventricular conduction system/
Aortic valve; endocardiits of AR p/w AV block and LBBB
Rifampin600mg q12. or cipro
Every 3-4 hours to determine appropritate time to start HAART
HBIG hep B immunoglobulin

11. How long abx is given in pseudomonas infection?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
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
Need lumbar puncture to relieve pressure; they have high opening pressure >350

12. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
If a sample is ELISA positive - it is tested fro western blot for confirmation
Need lumbar puncture to relieve pressure; they have high opening pressure >350
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

13. what would be viral load after 4 weeks
Others lesions are ring enhancing and have mass effect while PML don't
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
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
<5000 copies/ml

14. dame that has already occurred
Cd4 count
Blastomycosis
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
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

15. When to give prophylaxis against MAC
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
Voriconazol. mycetoma-surgical removal
Blastomycosis
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

16. What is tx for herpes zoster
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.
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Acyclovir
Upper lobes; any fibrosis in this area suggestive of latent TB

17. antibiotic with good prostate penetration?
Rifampin600mg q12. or cipro
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Within 6 months viral load will be <50
Clostridium perfringens after penetrative injuries/wounds

18. 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
Ampicillin-sublactam; most bites contain eikenella
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.
Bronchoalveolar washing and transbronchial biopsy

19. How to dx adequate response to HBV vaccine
Vaccine titer >10mU/ml
Mainly clinical - epidemiological and seasonal setting
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
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

20. How often HIV postiive patients CD4 count needs to be evaluated?
Every 3-4 hours to determine appropritate time to start HAART
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
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
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

21. How to dx bacterial meningitis from CSF study?

22. after exposure of HIV when antibody testing is performed?
ELISA; initial visit - 6 - 12 and 24 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
Pegylated interferon and lamivudine
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

23. when HIV patient develop pcp?
Td every 10 years - tdap once before 65 and after 65
High risk 19-64; 1-2 dose - above 65; one dose
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
When cd4 count falls below 200. 2p in pcp =200

24. How to tx pcp?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
High risk 19-64; 1-2 dose - above 65; one dose
Within 6 months viral load will be <50
Voriconazol. mycetoma-surgical removal

25. 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
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Need lumbar puncture to relieve pressure; they have high opening pressure >350
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

26. foot infections in DM
6-12 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
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Voriconazol. mycetoma-surgical removal

27. How to tx TSS?
Ampicillin-sublactam; most bites contain eikenella
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
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
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

28. infiltrate in upper lobe of lung?
Either TB or aspergillosis
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
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
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

29. What is the criteria for Spontaneous bact peritonitis
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Do EBV antibody test
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

30. systolic HTN in elderly
Viral load and CD4 count
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Aortic valve; endocardiits of AR p/w AV block and LBBB
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

31. after recent exposure - negative ELISA - How to confirm?
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Rifampin600mg q12. or cipro
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.

32. can HIV transmitted through human bite?
Postcoital voiding - increased intake of cranberry juice
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Either TB or aspergillosis
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

33. clinical manifestation of mucomycosis
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
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
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Vaccine titer >10mU/ml

34. what parameters increases risk of neurosyphilis in HIV patient
Viral load and CD4 count
Pt who have been treated before for 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.
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

35. What is the Tx of cryptococcal meninngitis
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Do EBV antibody test
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

36. when not to give INH therapy if ppd positive and patient asyptomatic
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
HBIG hep B immunoglobulin
Voriconazol. mycetoma-surgical removal
Pt who have been treated before for latent TB

37. How to differentiate different types of necrotizing fascitis?
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
<5000 copies/ml
Similar pathophysiology as ITP - tx zidovudine

38. wisconsin - missisipi - ohio
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Blastomycosis
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
HBIG hep B immunoglobulin

39. What is difference between uti relapse versus recurrence?
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
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
AA gradient >35 or Po2 <70
Within 6 months viral load will be <50

40. What is lag time to develop lyme arthritis after exposure to vector
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Do EBV antibody test
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

41. worsening of TB after starting HAART in HIV
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
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
Immune mediated; circulating IgG and IgM to penicillin derivatives

42. low grade fever - maculopapular rash - lymphadenopathy
Postcoital voiding - increased intake of cranberry juice
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
<500 copies/ml
Oropharyngeal secretions; hence named as kissing disease

43. What is the indication of corticosteroid in pcp infection?
Postcoital voiding - increased intake of cranberry juice
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
AA gradient >35 or Po2 <70

44. How to tx IM?
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
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

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

46. where TB normally affects
Pt who have been treated before for latent TB
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Upper lobes; any fibrosis in this area suggestive of latent TB
Immune mediated; circulating IgG and IgM to penicillin derivatives

47. How to tx chronic hep B
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Bronchoalveolar washing and transbronchial biopsy
Rifampin600mg q12. or cipro
Pegylated interferon and lamivudine

48. What are indicators for progression of HIV
Viral load and CD4 count
Aortic valve; endocardiits of AR p/w AV block and LBBB
6-12 weeks
Oropharyngeal secretions; hence named as kissing disease

49. hypertriglyceridemia in HIV
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Blastomycosis
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

50. How to give postexposure prophylaxis for HIV
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
HBIG hep B immunoglobulin
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w