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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. damae that is about to occur?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
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
HIV viral load

2. hypertension in children
Rifampin600mg q12. or cipro
Aortic valve; endocardiits of AR p/w AV block and LBBB
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
<5000 copies/ml

3. How to tx IM?
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
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
Pt who have been treated before for latent TB

4. rifampin
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Vaccine titer >10mU/ml
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Aortic valve; endocardiits of AR p/w AV block and LBBB

5. when not to give INH therapy if ppd positive and patient asyptomatic
Pt who have been treated before for latent TB
Postcoital voiding - increased intake of cranberry juice
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
Rifampin600mg q12. or cipro

6. which heart valve is closer to ventricular conduction system/
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Every 3-4 hours to determine appropritate time to start HAART
Bronchoalveolar washing and transbronchial biopsy
Aortic valve; endocardiits of AR p/w AV block and LBBB

7. hypertriglyceridemia in HIV
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Aortic valve; endocardiits of AR p/w AV block and LBBB
Clostridium perfringens after penetrative injuries/wounds
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

8. What is characteristic for dx of rocky mountain spotted fever?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Pregnacy - urologic procedure - hip arthoplastu
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

9. How to tx chronic hep B
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Pegylated interferon and lamivudine

10. INH
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Upper lobes; any fibrosis in this area suggestive of latent TB
Need lumbar puncture to relieve pressure; they have high opening pressure >350
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

11. What is the classic signs of nec fasc?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
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

12. when western blot is done for HIV testing
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Ampicillin-sublactam; most bites contain eikenella
If a sample is ELISA positive - it is tested fro western blot for confirmation

13. infiltrate in upper lobe of lung?
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Either TB or aspergillosis
Pregnacy - urologic procedure - hip arthoplastu
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

14. When to give abx to prevent recurrent uti
Bronchoalveolar washing and transbronchial biopsy
Voriconazol. mycetoma-surgical removal
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
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

15. what would be viral load after 2-4m of HAART?
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.
Mainly clinical - epidemiological and seasonal setting
<500 copies/ml
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

16. How often HIV postiive patients CD4 count needs to be evaluated?
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
Acyclovir
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

17. When to give prophylaxis against MAC
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Blastomycosis
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

18. What are indicators for progression of HIV
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Viral load and CD4 count
Pregnacy - urologic procedure - hip arthoplastu
Either TB or aspergillosis

19. where TB normally affects
Either TB or aspergillosis
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Clostridium perfringens after penetrative injuries/wounds
Upper lobes; any fibrosis in this area suggestive of latent TB

20. pneumococcal vaccine indication?
High risk 19-64; 1-2 dose - above 65; one dose
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
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
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 TSS?
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
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Rifampin600mg q12. or cipro
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

22. What is fatal consequence of RMSF?
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Ampicillin-sublactam; most bites contain eikenella
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

23. What is the criteria for Spontaneous bact peritonitis
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Others lesions are ring enhancing and have mass effect while PML don't
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

24. What is lag time to develop lyme arthritis after exposure to vector
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
ELISA; initial visit - 6 - 12 and 24 weeks;
<5000 copies/ml
If a sample is ELISA positive - it is tested fro western blot for confirmation

25. Tx of choice for human bites
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.
<5000 copies/ml
Aortic valve; endocardiits of AR p/w AV block and LBBB

26. How to dx?
Pegylated interferon and lamivudine
Mainly clinical - epidemiological and seasonal setting
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Monospot test which screen heteropile ab that agglutinate horse rbc

27. gas gangrene
Reddish orange discoloration of urine - feces - sweat - tears - sputum
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
Clostridium perfringens after penetrative injuries/wounds

28. What is difference between uti relapse versus recurrence?
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Every 3-4 hours to determine appropritate time to start HAART
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

29. after exposure of HIV when antibody testing is performed?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
ELISA; initial visit - 6 - 12 and 24 weeks;
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

30. When to tx influenza with antiviral therapy?
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
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
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.
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

31. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
HBIG hep B immunoglobulin
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
<500 copies/ml

32. acute febrile reaction develops after starting penicilin tx to syphilis patient
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
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

33. How to tx pcp?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
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
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

34. when we see echym gangrenosum?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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
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

35. How to dx IM?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Blastomycosis
Voriconazol. mycetoma-surgical removal

36. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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

37. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Viral load and CD4 count
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

38. can HIV transmitted through human bite?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
HBIG hep B immunoglobulin
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
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

39. what parameters increases risk of neurosyphilis in HIV patient
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 present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

40. How long abx is given in pseudomonas infection?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
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
Within 6 months viral load will be <50

41. What is tx for herpes zoster
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
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Acyclovir
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

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

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43. How long we tx chronic prostatis?
Pregnacy - urologic procedure - hip arthoplastu
Either TB or aspergillosis
6-12 weeks
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

44. What is the mch of ampicillin induced rash in IM
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Immune mediated; circulating IgG and IgM to penicillin derivatives

45. What is the Tx of STD uretheritis?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Oropharyngeal secretions; hence named as kissing disease
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
Td every 10 years - tdap once before 65 and after 65

46. dame that has already occurred
Cd4 count
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Others lesions are ring enhancing and have mass effect while PML don't
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

47. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Immune mediated; circulating IgG and IgM to penicillin derivatives
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
6-12 weeks
Within 6 months viral load will be <50

48. foot infections in DM
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

49. what if monospot test is neg in IM?
Either TB or aspergillosis
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Do EBV antibody test
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

50. HIV patient having fat deposition on back of neck and abdomen - like cushing
ELISA; initial visit - 6 - 12 and 24 weeks;
Td every 10 years - tdap once before 65 and after 65
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
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