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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 tx chronic hep B
Every 3-4 hours to determine appropritate time to start HAART
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Pegylated interferon and lamivudine

2. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Postcoital voiding - increased intake of cranberry juice
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
High risk 19-64; 1-2 dose - above 65; one dose
AA gradient >35 or Po2 <70

3. foot infections in DM
Mainly clinical - epidemiological and seasonal setting
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Pregnacy - urologic procedure - hip arthoplastu

4. pneumococcal vaccine indication?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
High risk 19-64; 1-2 dose - above 65; one dose

5. What is characteristic for dx of rocky mountain spotted fever?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
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

6. when not to give INH therapy if ppd positive and patient asyptomatic
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
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
Pt who have been treated before for latent TB
Others lesions are ring enhancing and have mass effect while PML don't

7. when HIV patient develop pcp?
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
AA gradient >35 or Po2 <70
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
When cd4 count falls below 200. 2p in pcp =200

8. antibiotic with good prostate penetration?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
If a sample is ELISA positive - it is tested fro western blot for confirmation
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

9. How to dx?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Upper lobes; any fibrosis in this area suggestive of latent TB
ELISA; initial visit - 6 - 12 and 24 weeks;
Mainly clinical - epidemiological and seasonal setting

10. how HAART therapy affects HIV viral loads?
Oropharyngeal secretions; hence named as kissing disease
Within 6 months viral load will be <50
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

11. How to dx adequate response to HBV vaccine
Rifampin600mg q12. or cipro
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
Vaccine titer >10mU/ml
<500 copies/ml

12. HIV patient having fat deposition on back of neck and abdomen - like cushing
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Bronchoalveolar washing and transbronchial biopsy
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

13. dame that has already occurred
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Reddish orange discoloration of urine - feces - sweat - tears - sputum
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Cd4 count

14. damae that is about to occur?
HIV viral load
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

15. How to dx progressive multifocal leukoencephalopathy
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

16. acute febrile reaction develops after starting penicilin tx to syphilis patient
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
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
If a sample is ELISA positive - it is tested fro western blot for confirmation
<5000 copies/ml

17. what parameters increases risk of neurosyphilis in HIV patient
When cd4 count falls below 200. 2p in pcp =200
<5000 copies/ml
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
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.

18. can HIV transmitted through human bite?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
ELISA; initial visit - 6 - 12 and 24 weeks;
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

19. what would be viral load after 2-4m of HAART?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
ELISA; initial visit - 6 - 12 and 24 weeks;
<500 copies/ml
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

20. rifampin
Reddish orange discoloration of urine - feces - sweat - tears - sputum
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
Clostridium perfringens after penetrative injuries/wounds
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

21. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Vaccine titer >10mU/ml
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

22. What is tx for herpes zoster
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
Rifampin600mg q12. or cipro
Acyclovir

23. How to dx bacterial meningitis from CSF study?

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24. What is lag time to develop lyme arthritis after exposure to vector
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

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

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26. infiltrate in upper lobe of lung?
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Either TB or aspergillosis

27. chshould we tx IM with abx (ampicilin) if throat cx is positive?
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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
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

28. worsening of TB after starting HAART in HIV
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

29. What is tetanus - diptheria - pertusis recommendation?
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
Postcoital voiding - increased intake of cranberry juice
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

30. When to tx asymptomatic bacteriurea >100 -000?
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 syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Pregnacy - urologic procedure - hip arthoplastu
ELISA; initial visit - 6 - 12 and 24 weeks;

31. What is fatal consequence of RMSF?
Need lumbar puncture to relieve pressure; they have high opening pressure >350
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
ELISA and western blot of synovial fluid.
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

32. What is the mch of ampicillin induced rash in IM
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Cd4 count
HBIG hep B immunoglobulin
Immune mediated; circulating IgG and IgM to penicillin derivatives

33. What is the criteria for Spontaneous bact peritonitis
HBIG hep B immunoglobulin
Clostridium perfringens after penetrative injuries/wounds
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

34. where TB normally affects
Upper lobes; any fibrosis in this area suggestive of latent TB
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Acyclovir
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

35. after recent exposure - negative ELISA - How to confirm?
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Pegylated interferon and lamivudine
Acyclovir

36. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Every 3-4 hours to determine appropritate time to start HAART
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Need lumbar puncture to relieve pressure; they have high opening pressure >350

37. How to confirm chlamydia infection?
If a sample is ELISA positive - it is tested fro western blot for confirmation
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.
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

38. how im is transmitted?
Pegylated interferon and lamivudine
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
Cd4 count
Oropharyngeal secretions; hence named as kissing disease

39. What is the indication of corticosteroid in pcp infection?
AA gradient >35 or Po2 <70
Either TB or aspergillosis
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Vaccine titer >10mU/ml

40. drugs work well on hypertriglyceridia?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
ELISA and western blot of synovial fluid.
Pegylated interferon and lamivudine
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

41. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
PML; focal neurological deficit like MM; no specific tx; regress with HAART
If a sample is ELISA positive - it is tested fro western blot for confirmation
Aortic valve; endocardiits of AR p/w AV block and LBBB

42. What is the Tx of cryptococcal meninngitis
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

43. How to differentiat PML from toxoxplasmosis - cns lymphoma adn brain abscess

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44. How to tx TSS?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Vaccine titer >10mU/ml
Others lesions are ring enhancing and have mass effect while PML don't
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

45. systolic HTN in elderly
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
HIV viral load
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Immune mediated; circulating IgG and IgM to penicillin derivatives

46. When to tx influenza with antiviral therapy?
Mainly clinical - epidemiological and seasonal setting
If a sample is ELISA positive - it is tested fro western blot for confirmation
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
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

47. reddish colored papules with central umbilication in HIV or immunocompromised patient
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Oropharyngeal secretions; hence named as kissing disease
Either TB or aspergillosis
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

48. How to dx IM?
Blastomycosis
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Pegylated interferon and lamivudine
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

49. How to dx IM?
Pregnacy - urologic procedure - hip arthoplastu
Monospot test which screen heteropile ab that agglutinate horse rbc
Vaccine titer >10mU/ml
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

50. 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
Rifampin600mg q12. or cipro
Either TB or aspergillosis
Oropharyngeal secretions; hence named as kissing disease