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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. When not to tx asymptomatic bacteriura?
ELISA and western blot of synovial fluid.
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
Non pregnant premanopausal - elderly - dm - sci - chronic foley
High risk 19-64; 1-2 dose - above 65; one dose

2. hypertension in children
Every 3-4 hours to determine appropritate time to start HAART
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

3. low grade fever - maculopapular rash - lymphadenopathy
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Monospot test which screen heteropile ab that agglutinate horse rbc
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

4. What is used for prophylaxis against meningo..meningitis?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Others lesions are ring enhancing and have mass effect while PML don't
Cd4 count
Rifampin600mg q12. or cipro

5. thrombocytopenia in HIV
Cd4 count
6-12 weeks
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Similar pathophysiology as ITP - tx zidovudine

6. which heart valve is closer to ventricular conduction system/
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
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
Aortic valve; endocardiits of AR p/w AV block and LBBB

7. What is lag time to develop lyme arthritis after exposure to vector
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
HBIG hep B immunoglobulin
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

8. damae that is about to occur?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Every 3-4 hours to determine appropritate time to start HAART
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
HIV viral load

9. how im is transmitted?
Blastomycosis
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Oropharyngeal secretions; hence named as kissing disease

10. How to tx chronic hep B
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
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
HBIG hep B immunoglobulin
Pegylated interferon and lamivudine

11. aspergillosis
Vaccine titer >10mU/ml
Voriconazol. mycetoma-surgical removal
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

12. clinical manifestation of mucomycosis
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Clostridium perfringens after penetrative injuries/wounds
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

13. What is the indication of corticosteroid in pcp infection?
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
AA gradient >35 or Po2 <70
Pt who have been treated before for latent TB

14. foot infections in DM
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Ampicillin-sublactam; most bites contain eikenella
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

15. What is the classic signs of nec fasc?
PML; focal neurological deficit like MM; no specific tx; regress with HAART
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
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

16. What are the behavioral interventions decrease the risk of UTI
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
6-12 weeks
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Postcoital voiding - increased intake of cranberry juice

17. can HIV transmitted through human bite?
Mainly clinical - epidemiological and seasonal setting
Within 6 months viral load will be <50
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

18. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Pregnacy - urologic procedure - hip arthoplastu
Need lumbar puncture to relieve pressure; they have high opening pressure >350

19. causative organisms of uti
Clostridium perfringens after penetrative injuries/wounds
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
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

20. What is the Tx of STD uretheritis?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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

21. When to give abx to prevent recurrent uti
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
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
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

22. rifampin
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Viral load and CD4 count
Pegylated interferon and lamivudine
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.

23. What is the pathophysiology of Meningococcal meningitis?
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Need lumbar puncture to relieve pressure; they have high opening pressure >350

24. Tx of choice for human bites
Ampicillin-sublactam; most bites contain eikenella
Voriconazol. mycetoma-surgical removal
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Aortic valve; endocardiits of AR p/w AV block and LBBB

25. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
HBIG hep B immunoglobulin
Pregnacy - urologic procedure - hip arthoplastu
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

26. How to differentiate different types of necrotizing fascitis?
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
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
AA gradient >35 or Po2 <70
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

27. drugs work well on hypertriglyceridia?
High risk 19-64; 1-2 dose - above 65; one dose
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
<5000 copies/ml
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

28. what if monospot test is neg in IM?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
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
Do EBV antibody test

29. INH
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
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
Oropharyngeal secretions; hence named as kissing disease

30. How to tx pcp?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Cd4 count
Pegylated interferon and lamivudine

31. 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
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Monospot test which screen heteropile ab that agglutinate horse rbc
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)

32. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Viral load and CD4 count
PML; focal neurological deficit like MM; no specific tx; regress with HAART

33. What is difference between uti relapse versus recurrence?
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
Either TB or aspergillosis
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
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

34. What is fatal consequence of RMSF?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Clostridium perfringens after penetrative injuries/wounds
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Similar pathophysiology as ITP - tx zidovudine

35. What is the mch of ampicillin induced rash in IM
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.
Ampicillin-sublactam; most bites contain eikenella
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

36. gas gangrene
HBIG hep B immunoglobulin
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Clostridium perfringens after penetrative injuries/wounds

37. How often viral load is monitored after HAART?
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
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Mainly clinical - epidemiological and seasonal setting

38. What is tx for herpes zoster
Immune mediated; circulating IgG and IgM to penicillin derivatives
Oropharyngeal secretions; hence named as kissing disease
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Acyclovir

39. 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
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
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
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

40. What is the prognosis of lyme arthritis?
Viral load and CD4 count
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Immune mediated; circulating IgG and IgM to penicillin derivatives

41. How long abx is given in pseudomonas infection?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Viral load and CD4 count
Every 3-4 hours to determine appropritate time to start HAART
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

42. How to dx?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Mainly clinical - epidemiological and seasonal setting
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
High risk 19-64; 1-2 dose - above 65; one dose

43. How to dx adequate response to HBV vaccine
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Mainly clinical - epidemiological and seasonal setting
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Vaccine titer >10mU/ml

44. How to dx cryptococal meninggits
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
HIV viral load
Similar pathophysiology as ITP - tx zidovudine
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

45. What is the criteria for Spontaneous bact peritonitis
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)
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

46. when we see echym gangrenosum?
Oropharyngeal secretions; hence named as kissing disease
Voriconazol. mycetoma-surgical removal
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.
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

47. 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
PML; focal neurological deficit like MM; no specific tx; regress with HAART
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

48. wisconsin - missisipi - ohio
Viral load and CD4 count
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Blastomycosis

49. after recent exposure - negative ELISA - How to confirm?
Oropharyngeal secretions; hence named as kissing disease
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Rifampin600mg q12. or cipro

50. when western blot is done for HIV testing
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
HBIG hep B immunoglobulin
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
If a sample is ELISA positive - it is tested fro western blot for confirmation