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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. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
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
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

2. Tx of choice for human bites
Ampicillin-sublactam; most bites contain eikenella
Aortic valve; endocardiits of AR p/w AV block and LBBB
Rifampin600mg q12. or cipro
Voriconazol. mycetoma-surgical removal

3. How long we tx chronic prostatis?
Pegylated interferon and lamivudine
6-12 weeks
Within 6 months viral load will be <50
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

4. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
High risk 19-64; 1-2 dose - above 65; one dose
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

5. How long abx is given in pseudomonas infection?
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
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
When cd4 count falls below 200. 2p in pcp =200

6. How to dx 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
Cd4 count
Monospot test which screen heteropile ab that agglutinate horse rbc
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

7. damae that is about to occur?
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
HIV viral load
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

8. How to differentiate different types of necrotizing fascitis?
Pt who have been treated before for latent TB
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
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

9. What is the pathophysiology of Meningococcal meningitis?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Mainly clinical - epidemiological and seasonal setting
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Monospot test which screen heteropile ab that agglutinate horse rbc

10. wisconsin - missisipi - ohio
Cd4 count
HIV viral load
Blastomycosis
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

11. What is difference between uti relapse versus recurrence?
Postcoital voiding - increased intake of cranberry juice
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
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
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

12. What is characteristic for dx of rocky mountain spotted fever?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
HBIG hep B immunoglobulin
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

13. What is the prognosis of lyme arthritis?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Similar pathophysiology as ITP - tx zidovudine
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

14. When to give abx to prevent recurrent uti
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
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
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
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

15. How to dx cryptococal meninggits
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Pregnacy - urologic procedure - hip arthoplastu
Postcoital voiding - increased intake of cranberry juice

16. How to tx pcp?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
When cd4 count falls below 200. 2p in pcp =200
Oropharyngeal secretions; hence named as kissing disease
Every 3-4 hours to determine appropritate time to start HAART

17. What are indicators for progression of HIV
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Bronchoalveolar washing and transbronchial biopsy
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Viral load and CD4 count

18. drugs work well on hypertriglyceridia?
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Oropharyngeal secretions; hence named as kissing disease

19. which heart valve is closer to ventricular conduction system/
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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
Aortic valve; endocardiits of AR p/w AV block and LBBB

20. foot infections in DM
Pt who have been treated before for latent TB
ELISA; initial visit - 6 - 12 and 24 weeks;
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

21. after recent exposure - negative ELISA - How to confirm?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
If a sample is ELISA positive - it is tested fro western blot for confirmation
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
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

22. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
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
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

23. acute febrile reaction develops after starting penicilin tx to syphilis patient
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Oropharyngeal secretions; hence named as kissing disease
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

24. How to dx?
Vaccine titer >10mU/ml
Mainly clinical - epidemiological and seasonal setting
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Reddish orange discoloration of urine - feces - sweat - tears - sputum

25. pathophysiology of toxic shock syndrom?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
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.
Either TB or aspergillosis

26. How to dx bacterial meningitis from CSF study?

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27. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Oropharyngeal secretions; hence named as kissing disease
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

28. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Oropharyngeal secretions; hence named as kissing disease
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

29. When to tx asymptomatic bacteriurea >100 -000?
Pregnacy - urologic procedure - hip arthoplastu
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Td every 10 years - tdap once before 65 and after 65

30. causative organisms of uti
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
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
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Do EBV antibody test

31. rifampin
Similar pathophysiology as ITP - tx zidovudine
6-12 weeks
Reddish orange discoloration of urine - feces - sweat - tears - sputum
ELISA; initial visit - 6 - 12 and 24 weeks;

32. How to tx pseudomonas?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Every 3-4 hours to determine appropritate time to start HAART

33. How to dx IM?
Viral load and CD4 count
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Acyclovir
Pt who have been treated before for latent TB

34. 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
If a sample is ELISA positive - it is tested fro western blot for confirmation
Do EBV antibody test
AA gradient >35 or Po2 <70

35. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
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
Bronchoalveolar washing and transbronchial biopsy
HBIG hep B immunoglobulin
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

36. What is the mch of ampicillin induced rash in IM
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Immune mediated; circulating IgG and IgM to penicillin derivatives
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

37. HIV patient having fat deposition on back of neck and abdomen - like cushing
Non pregnant premanopausal - elderly - dm - sci - chronic foley
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 lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

38. How to tx chronic hep B
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Pegylated interferon and lamivudine
Aortic valve; endocardiits of AR p/w AV block and LBBB

39. INH
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Others lesions are ring enhancing and have mass effect while PML don't
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
<500 copies/ml

40. how im is transmitted?
Oropharyngeal secretions; hence named as kissing disease
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Similar pathophysiology as ITP - tx zidovudine
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

41. How to dx progressive multifocal leukoencephalopathy
Td every 10 years - tdap once before 65 and after 65
Need lumbar puncture to relieve pressure; they have high opening pressure >350
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

42. When to tx influenza with antiviral therapy?
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
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Viral load and CD4 count
Reddish orange discoloration of urine - feces - sweat - tears - sputum

43. How to dx adequate response to HBV vaccine
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Vaccine titer >10mU/ml
Monospot test which screen heteropile ab that agglutinate horse rbc
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

44. when HIV patient develop pcp?
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
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
When cd4 count falls below 200. 2p in pcp =200
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

45. How to dx lyme arthritis?
Ampicillin-sublactam; most bites contain eikenella
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
ELISA and western blot of synovial fluid.
When cd4 count falls below 200. 2p in pcp =200

46. What are the subjective /objective measure of encephalopathy?
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Td every 10 years - tdap once before 65 and after 65
Mainly clinical - epidemiological and seasonal setting
Clostridium perfringens after penetrative injuries/wounds

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

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48. reddish colored papules with central umbilication in HIV or immunocompromised patient
Every 3-4 hours to determine appropritate time to start HAART
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
Immune mediated; circulating IgG and IgM to penicillin derivatives
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

49. 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
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

50. can HIV transmitted through human bite?
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
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