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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 dx lyme arthritis?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
ELISA and western blot of synovial fluid.

2. How to confirm chlamydia infection?
Either TB or aspergillosis
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
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
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

3. infiltrate in upper lobe of lung?
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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

4. when western blot is done for HIV testing
If a sample is ELISA positive - it is tested fro western blot for confirmation
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
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
Within 6 months viral load will be <50

5. How to tx pseudomonas?
Pegylated interferon and lamivudine
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Every 3-4 hours to determine appropritate time to start HAART
Others lesions are ring enhancing and have mass effect while PML don't

6. low grade fever - maculopapular rash - lymphadenopathy
Vaccine titer >10mU/ml
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

7. systolic HTN in elderly
6-12 weeks
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Pegylated interferon and lamivudine

8. causative organisms of uti
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
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

9. When to tx influenza with antiviral therapy?
Td every 10 years - tdap once before 65 and after 65
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
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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

10. drugs work well on hypertriglyceridia?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
AA gradient >35 or Po2 <70
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

11. clinical manifestation of mucomycosis
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Non pregnant premanopausal - elderly - dm - sci - chronic foley
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

12. aspergillosis
Voriconazol. mycetoma-surgical removal
AA gradient >35 or Po2 <70
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Reddish orange discoloration of urine - feces - sweat - tears - sputum

13. acute febrile reaction develops after starting penicilin tx to syphilis patient
Bronchoalveolar washing and transbronchial biopsy
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
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
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

14. How long we tx chronic prostatis?
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
6-12 weeks
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

15. what would be viral load after 4 weeks
<5000 copies/ml
If a sample is ELISA positive - it is tested fro western blot for confirmation
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
Td every 10 years - tdap once before 65 and after 65

16. Tx of choice for human bites
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Ampicillin-sublactam; most bites contain eikenella
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

17. How to dx IM?
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
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

18. INH
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Mainly clinical - epidemiological and seasonal setting

19. reddish colored papules with central umbilication in HIV or immunocompromised patient
HIV viral load
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.
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
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

20. What is tx for herpes zoster
Immune mediated; circulating IgG and IgM to penicillin derivatives
Acyclovir
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Ampicillin-sublactam; most bites contain eikenella

21. How to dx cryptococal meninggits
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Cd4 count
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

22. which heart valve is closer to ventricular conduction system/
Aortic valve; endocardiits of AR p/w AV block and LBBB
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
AA gradient >35 or Po2 <70

23. how im is transmitted?
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Oropharyngeal secretions; hence named as kissing disease
Voriconazol. mycetoma-surgical removal
PML; focal neurological deficit like MM; no specific tx; regress with HAART

24. thrombocytopenia in HIV
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
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

25. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
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
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Every 3-4 hours to determine appropritate time to start HAART

26. What is the pathophysiology of Meningococcal meningitis?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
6-12 weeks
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
HIV viral load

27. HIV patient having fat deposition on back of neck and abdomen - like cushing
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
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

28. foot infections in DM
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Blastomycosis
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

29. chshould we tx IM with abx (ampicilin) if throat cx is positive?
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
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

30. pneumococcal vaccine indication?
HBIG hep B immunoglobulin
High risk 19-64; 1-2 dose - above 65; one dose
ELISA and western blot of synovial fluid.
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

31. when not to give INH therapy if ppd positive and patient asyptomatic
Pt who have been treated before for latent TB
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
AA gradient >35 or Po2 <70
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

32. How to tx TSS?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Cd4 count
Voriconazol. mycetoma-surgical removal
Do EBV antibody test

33. wisconsin - missisipi - ohio
Blastomycosis
Do EBV antibody test
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
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

34. How often viral load is monitored after HAART?
High risk 19-64; 1-2 dose - above 65; one dose
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Either TB or aspergillosis

35. How to tx chronic hep B
Pegylated interferon and lamivudine
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Oropharyngeal secretions; hence named as kissing disease

36. pathophysiology of toxic shock syndrom?
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
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Rifampin600mg q12. or cipro
Viral load and CD4 count

37. how HAART therapy affects HIV viral loads?
ELISA and western blot of synovial fluid.
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Within 6 months viral load will be <50
Monospot test which screen heteropile ab that agglutinate horse rbc

38. When to tx asymptomatic bacteriurea >100 -000?
Pregnacy - urologic procedure - hip arthoplastu
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
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
Acyclovir

39. How to tx pcp?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Td every 10 years - tdap once before 65 and after 65
Pregnacy - urologic procedure - hip arthoplastu

40. How often HIV postiive patients CD4 count needs to be evaluated?
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.
Every 3-4 hours to determine appropritate time to start HAART
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

41. after recent exposure - negative ELISA - How to confirm?
Td every 10 years - tdap once before 65 and after 65
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Monospot test which screen heteropile ab that agglutinate horse rbc
Aortic valve; endocardiits of AR p/w AV block and LBBB

42. 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
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
Within 6 months viral load will be <50
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

43. antibiotic with good prostate penetration?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Oropharyngeal secretions; hence named as kissing disease
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Viral load and CD4 count

44. 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
Monospot test which screen heteropile ab that agglutinate horse rbc
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

45. How to give postexposure prophylaxis for HIV
HIV viral load
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Vaccine titer >10mU/ml

46. how CMV presents in immunocompromised patients
Reddish orange discoloration of urine - feces - sweat - tears - sputum
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
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

47. after exposure of HIV when antibody testing is performed?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
HIV viral load
ELISA; initial visit - 6 - 12 and 24 weeks;

48. What is fatal consequence of RMSF?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
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
ELISA and western blot of synovial fluid.
Vaccine titer >10mU/ml

49. what if monospot test is neg in IM?
Others lesions are ring enhancing and have mass effect while PML don't
Clostridium perfringens after penetrative injuries/wounds
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Do EBV antibody test

50. damae that is about to occur?
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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
HIV viral load