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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
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

2. systolic HTN in elderly
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
Similar pathophysiology as ITP - tx zidovudine
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

3. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Immune mediated; circulating IgG and IgM to penicillin derivatives
Monospot test which screen heteropile ab that agglutinate horse rbc
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
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

4. aspergillosis
Vaccine titer >10mU/ml
Voriconazol. mycetoma-surgical removal
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

5. How to dx lyme arthritis?
ELISA and western blot of synovial fluid.
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

6. How to tx pseudomonas?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
AA gradient >35 or Po2 <70
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Voriconazol. mycetoma-surgical removal

7. thrombocytopenia in HIV
Pegylated interferon and lamivudine
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Similar pathophysiology as ITP - tx zidovudine
HIV viral load

8. What are the subjective /objective measure of encephalopathy?
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
High risk 19-64; 1-2 dose - above 65; one dose
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

9. infiltrate in upper lobe of lung?
Viral load and CD4 count
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Either TB or aspergillosis
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

10. What is the mch of ampicillin induced rash in IM
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Immune mediated; circulating IgG and IgM to penicillin derivatives
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
If a sample is ELISA positive - it is tested fro western blot for confirmation

11. damae that is about to occur?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
HIV viral load
Pt who have been treated before for latent TB

12. How to dx progressive multifocal leukoencephalopathy
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HBIG hep B immunoglobulin
<5000 copies/ml

13. What is difference between uti relapse versus recurrence?
6-12 weeks
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
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
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

14. worsening of TB after starting HAART in HIV
Cd4 count
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

15. What is the prognosis of lyme arthritis?
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
High risk 19-64; 1-2 dose - above 65; one dose
Voriconazol. mycetoma-surgical removal

16. 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
When cd4 count falls below 200. 2p in pcp =200
<500 copies/ml
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

17. How long abx is given in pseudomonas infection?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

18. low grade fever - maculopapular rash - lymphadenopathy
Every 3-4 hours to determine appropritate time to start HAART
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
6-12 weeks
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

19. INH
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

20. hypertension in children
Oropharyngeal secretions; hence named as kissing disease
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Ampicillin-sublactam; most bites contain eikenella

21. When to give abx to prevent recurrent uti
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
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Pegylated interferon and lamivudine
Acyclovir

22. pneumococcal vaccine indication?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Voriconazol. mycetoma-surgical removal
High risk 19-64; 1-2 dose - above 65; one dose
Others lesions are ring enhancing and have mass effect while PML don't

23. how im is transmitted?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Oropharyngeal secretions; hence named as kissing disease
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

24. pathophysiology of toxic shock syndrom?
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Do EBV antibody test
Mainly clinical - epidemiological and seasonal setting
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

25. hypertriglyceridemia in HIV
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 RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
ELISA; initial visit - 6 - 12 and 24 weeks;
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

26. What are indicators for progression of HIV
Oropharyngeal secretions; hence named as kissing disease
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Viral load and CD4 count
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

27. 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
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Clostridium perfringens after penetrative injuries/wounds

28. What is the criteria for Spontaneous bact peritonitis
6-12 weeks
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Similar pathophysiology as ITP - tx zidovudine

29. what if monospot test is neg in IM?
Do EBV antibody test
Upper lobes; any fibrosis in this area suggestive of latent TB
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

30. when not to give INH therapy if ppd positive and patient asyptomatic
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
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
Rifampin600mg q12. or cipro

31. How often HIV postiive patients CD4 count needs to be evaluated?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Rifampin600mg q12. or cipro
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Every 3-4 hours to determine appropritate time to start HAART

32. How to dx?
High risk 19-64; 1-2 dose - above 65; one dose
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Mainly clinical - epidemiological and seasonal setting
AA gradient >35 or Po2 <70

33. what would be viral load after 4 weeks
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
<5000 copies/ml
Blastomycosis
Acyclovir

34. gas gangrene
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Bronchoalveolar washing and transbronchial biopsy
Clostridium perfringens after penetrative injuries/wounds

35. When to tx influenza with antiviral therapy?
Do EBV antibody test
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
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
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

36. how CMV presents in immunocompromised patients
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

37. can HIV transmitted through human bite?
Cd4 count
Others lesions are ring enhancing and have mass effect while PML don't
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

38. How to tx pcp?
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Ampicillin-sublactam; most bites contain eikenella
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

39. How to confirm dx if pcp?
Bronchoalveolar washing and transbronchial biopsy
Do EBV antibody test
Others lesions are ring enhancing and have mass effect while PML don't
Acyclovir

40. after exposure of HIV when antibody testing is performed?
Postcoital voiding - increased intake of cranberry juice
ELISA; initial visit - 6 - 12 and 24 weeks;
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.
Reddish orange discoloration of urine - feces - sweat - tears - sputum

41. how HAART therapy affects HIV viral loads?
AA gradient >35 or Po2 <70
Within 6 months viral load will be <50
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Upper lobes; any fibrosis in this area suggestive of latent TB

42. How to tx chronic hep B
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Do EBV antibody test
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Pegylated interferon and lamivudine

43. when western blot is done for HIV testing
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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

44. What is used for prophylaxis against meningo..meningitis?
Rifampin600mg q12. or cipro
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HBIG hep B immunoglobulin

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

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46. antibiotic with good prostate penetration?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Do EBV antibody test
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Pt who have been treated before for latent TB

47. clinical manifestation of mucomycosis
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Ampicillin-sublactam; most bites contain eikenella

48. What is the Tx of STD uretheritis?
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
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

49. acute onset +rusty sputum
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Pt who have been treated before for latent TB
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

50. How to dx cryptococal meninggits
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
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