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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. What is lag time to develop lyme arthritis after exposure to vector
Others lesions are ring enhancing and have mass effect while PML don't
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
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

2. how HAART therapy affects HIV viral loads?
High risk 19-64; 1-2 dose - above 65; one dose
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
Within 6 months viral load will be <50

3. What is the indication of corticosteroid in pcp infection?
Mainly clinical - epidemiological and seasonal setting
Either TB or aspergillosis
AA gradient >35 or Po2 <70
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

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

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5. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Similar pathophysiology as ITP - tx zidovudine
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
HBIG hep B immunoglobulin

6. What is used for prophylaxis against meningo..meningitis?
<5000 copies/ml
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
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Rifampin600mg q12. or cipro

7. What is the Tx of STD uretheritis?
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
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
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
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

8. INH
Pregnacy - urologic procedure - hip arthoplastu
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Vaccine titer >10mU/ml

9. Tx of choice for human bites
Within 6 months viral load will be <50
Similar pathophysiology as ITP - tx zidovudine
Ampicillin-sublactam; most bites contain eikenella
HIV viral load

10. clinical manifestation of mucomycosis
AA gradient >35 or Po2 <70
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Cd4 count
Aortic valve; endocardiits of AR p/w AV block and LBBB

11. What are indicators for progression of HIV
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Viral load and CD4 count
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Either TB or aspergillosis

12. What is the pathophysiology of Meningococcal meningitis?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Cd4 count
Pregnacy - urologic procedure - hip arthoplastu
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

13. acute onset +rusty sputum
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
Immune mediated; circulating IgG and IgM to penicillin derivatives
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

14. What is characteristic for dx of rocky mountain spotted fever?
Do EBV antibody test
Clostridium perfringens after penetrative injuries/wounds
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

15. low grade fever - maculopapular rash - lymphadenopathy
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Rifampin600mg q12. or cipro

16. How to dx IM?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
<500 copies/ml
Blastomycosis

17. systolic HTN in elderly
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Mainly clinical - epidemiological and seasonal setting
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

18. What are the behavioral interventions decrease the risk of UTI
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
Postcoital voiding - increased intake of cranberry juice
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Pt who have been treated before for latent TB

19. reddish colored papules with central umbilication in HIV or immunocompromised patient
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
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
AA gradient >35 or Po2 <70
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

20. after exposure of HIV when antibody testing is performed?
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
Cd4 count
ELISA; initial visit - 6 - 12 and 24 weeks;
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

21. How to dx bacterial meningitis from CSF study?

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22. How to give postexposure prophylaxis for HIV
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
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
ELISA; initial visit - 6 - 12 and 24 weeks;

23. when western blot is done for HIV testing
ELISA and western blot of synovial fluid.
If a sample is ELISA positive - it is tested fro western blot for confirmation
Mainly clinical - epidemiological and seasonal setting
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

24. How to confirm dx if pcp?
Bronchoalveolar washing and transbronchial biopsy
Rifampin600mg q12. or cipro
HBIG hep B immunoglobulin
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

25. How to differentiate gonococcal and nongonoccal urethritis?
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
Pegylated interferon and lamivudine
6-12 weeks
If a sample is ELISA positive - it is tested fro western blot for confirmation

26. How long abx is given in pseudomonas infection?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

27. how CMV presents in immunocompromised patients
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
HIV viral load
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

28. when HIV patient develop pcp?
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
When cd4 count falls below 200. 2p in pcp =200
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

29. pneumococcal vaccine indication?
High risk 19-64; 1-2 dose - above 65; one dose
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Postcoital voiding - increased intake of cranberry juice

30. How to dx cryptococal meninggits
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Postcoital voiding - increased intake of cranberry juice
Monospot test which screen heteropile ab that agglutinate horse rbc

31. INH
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
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
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Voriconazol. mycetoma-surgical removal

32. How to dx lyme arthritis?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
ELISA and western blot of synovial fluid.
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Ampicillin-sublactam; most bites contain eikenella

33. How to tx pcp?
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Immune mediated; circulating IgG and IgM to penicillin derivatives
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Cd4 count

34. pathophysiology of toxic shock syndrom?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Reddish orange discoloration of urine - feces - sweat - tears - sputum

35. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Pregnacy - urologic procedure - hip arthoplastu

36. 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
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
<500 copies/ml
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

37. What is the criteria for Spontaneous bact peritonitis
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

38. How often viral load is monitored after HAART?
If a sample is ELISA positive - it is tested fro western blot for confirmation
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
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

39. hypertension in children
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
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

40. What is tetanus - diptheria - pertusis recommendation?
Clostridium perfringens after penetrative injuries/wounds
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Td every 10 years - tdap once before 65 and after 65
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

41. How to dx progressive multifocal leukoencephalopathy
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Either TB or aspergillosis
Vaccine titer >10mU/ml
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

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

43. where TB normally affects
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Upper lobes; any fibrosis in this area suggestive of latent TB
ELISA; initial visit - 6 - 12 and 24 weeks;
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

44. infiltrate in upper lobe of lung?
Either TB or aspergillosis
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
<500 copies/ml
Oropharyngeal secretions; hence named as kissing disease

45. after recent exposure - negative ELISA - How to confirm?
Pegylated interferon and lamivudine
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
Others lesions are ring enhancing and have mass effect while PML don't
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

46. How to confirm chlamydia infection?
<5000 copies/ml
HBIG hep B immunoglobulin
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

47. acute febrile reaction develops after starting penicilin tx to syphilis patient
Cd4 count
HBIG hep B immunoglobulin
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

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

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49. what if monospot test is neg in IM?
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
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
ELISA; initial visit - 6 - 12 and 24 weeks;
Do EBV antibody test

50. How to tx chronic hep B
Pegylated interferon and lamivudine
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
Similar pathophysiology as ITP - tx zidovudine
Clostridium perfringens after penetrative injuries/wounds