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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. Tx of choice for human bites
<5000 copies/ml
Mainly clinical - epidemiological and seasonal setting
Ampicillin-sublactam; most bites contain eikenella
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

2. What is tetanus - diptheria - pertusis recommendation?
Td every 10 years - tdap once before 65 and after 65
Immune mediated; circulating IgG and IgM to penicillin derivatives
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
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

3. What are the subjective /objective measure of encephalopathy?
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Pegylated interferon and lamivudine
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

4. INH
Upper lobes; any fibrosis in this area suggestive of latent TB
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Acyclovir
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

5. what if monospot test is neg in IM?
Do EBV antibody test
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Pegylated interferon and lamivudine
Pt who have been treated before for latent TB

6. how im is transmitted?
Oropharyngeal secretions; hence named as kissing disease
If a sample is ELISA positive - it is tested fro western blot for confirmation
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

7. What is the Tx of STD uretheritis?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
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

8. pneumococcal vaccine indication?
PML; focal neurological deficit like MM; no specific tx; regress with HAART
When cd4 count falls below 200. 2p in pcp =200
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
High risk 19-64; 1-2 dose - above 65; one dose

9. clinical manifestation of mucomycosis
HIV viral load
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
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

10. aspergillosis
<5000 copies/ml
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Voriconazol. mycetoma-surgical removal

11. gas gangrene
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
Clostridium perfringens after penetrative injuries/wounds
Aortic valve; endocardiits of AR p/w AV block and LBBB

12. hypertension in children
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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
Aortic valve; endocardiits of AR p/w AV block and LBBB
Monospot test which screen heteropile ab that agglutinate horse rbc

13. after recent exposure - negative ELISA - How to confirm?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
PML; focal neurological deficit like MM; no specific tx; regress with HAART
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
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

14. How to dx progressive multifocal leukoencephalopathy
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HIV viral load
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

15. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Similar pathophysiology as ITP - tx zidovudine
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Voriconazol. mycetoma-surgical removal
Viral load and CD4 count

16. what parameters increases risk of neurosyphilis in HIV patient
Monospot test which screen heteropile ab that agglutinate horse rbc
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.
High risk 19-64; 1-2 dose - above 65; one dose
Reddish orange discoloration of urine - feces - sweat - tears - sputum

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

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18. How to confirm dx if pcp?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Aortic valve; endocardiits of AR p/w AV block and LBBB
Bronchoalveolar washing and transbronchial biopsy

19. can HIV transmitted through human bite?
AA gradient >35 or Po2 <70
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
HIV viral load
Postcoital voiding - increased intake of cranberry juice

20. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

21. dame that has already occurred
Cd4 count
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Immune mediated; circulating IgG and IgM to penicillin derivatives
High risk 19-64; 1-2 dose - above 65; one dose

22. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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

23. systolic HTN in elderly
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
When cd4 count falls below 200. 2p in pcp =200
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

24. How to tx pseudomonas?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
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
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

25. 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)
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

26. How to dx IM?
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Postcoital voiding - increased intake of cranberry juice
Monospot test which screen heteropile ab that agglutinate horse rbc
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

27. What is the prognosis of lyme arthritis?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

28. When not to tx asymptomatic bacteriura?
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

29. when not to give INH therapy if ppd positive and patient asyptomatic
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Aortic valve; endocardiits of AR p/w AV block and LBBB
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Pt who have been treated before for latent TB

30. What are indicators for progression of HIV
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
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

31. infiltrate in upper lobe of lung?
Within 6 months viral load will be <50
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Either TB or aspergillosis
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

32. What is the Tx of cryptococcal meninngitis
Cd4 count
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
Upper lobes; any fibrosis in this area suggestive of latent TB
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

33. What is used for prophylaxis against meningo..meningitis?
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
6-12 weeks
ELISA; initial visit - 6 - 12 and 24 weeks;
Rifampin600mg q12. or cipro

34. How to tx IM?
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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

35. antibiotic with good prostate penetration?
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
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

36. What is the classic signs of nec fasc?
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
6-12 weeks
Monospot test which screen heteropile ab that agglutinate horse rbc
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

37. What is fatal consequence of RMSF?
Either TB or aspergillosis
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
ELISA and western blot of synovial fluid.

38. When to tx influenza with antiviral therapy?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Similar pathophysiology as ITP - tx zidovudine
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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

39. How to dx IM?
Cd4 count
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Do EBV antibody test

40. after exposure of HIV when antibody testing is performed?
Others lesions are ring enhancing and have mass effect while PML don't
Upper lobes; any fibrosis in this area suggestive of latent TB
Need lumbar puncture to relieve pressure; they have high opening pressure >350
ELISA; initial visit - 6 - 12 and 24 weeks;

41. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
When cd4 count falls below 200. 2p in pcp =200
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
HBIG hep B immunoglobulin
Voriconazol. mycetoma-surgical removal

42. damae that is about to occur?
Postcoital voiding - increased intake of cranberry juice
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 viral load
Pt who have been treated before for latent TB

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

44. acute onset +rusty sputum
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Aortic valve; endocardiits of AR p/w AV block and LBBB
Td every 10 years - tdap once before 65 and after 65
Every 3-4 hours to determine appropritate time to start HAART

45. INH
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
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.
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

46. pathophysiology of toxic shock syndrom?
Immune mediated; circulating IgG and IgM to penicillin derivatives
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.
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

47. how HAART therapy affects HIV viral loads?
Within 6 months viral load will be <50
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
ELISA and western blot of synovial fluid.
Td every 10 years - tdap once before 65 and after 65

48. How to dx?
Monospot test which screen heteropile ab that agglutinate horse rbc
Upper lobes; any fibrosis in this area suggestive of latent TB
Mainly clinical - epidemiological and seasonal setting
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

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

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50. What are the behavioral interventions decrease the risk of UTI
Postcoital voiding - increased intake of cranberry juice
Pt who have been treated before for latent TB
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