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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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1. systolic HTN in elderly
Rifampin600mg q12. or cipro
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
6-12 weeks
High risk 19-64; 1-2 dose - above 65; one dose

2. drugs work well on hypertriglyceridia?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

3. which heart valve is closer to ventricular conduction system/
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Aortic valve; endocardiits of AR p/w AV block and LBBB
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Non pregnant premanopausal - elderly - dm - sci - chronic foley

4. How to dx adequate response to HBV vaccine
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Vaccine titer >10mU/ml
Oropharyngeal secretions; hence named as kissing disease
Voriconazol. mycetoma-surgical removal

5. after exposure of HIV when antibody testing is performed?
ELISA; initial visit - 6 - 12 and 24 weeks;
Viral load and CD4 count
Pt who have been treated before for latent TB
Need lumbar puncture to relieve pressure; they have high opening pressure >350

6. How to dx?
<500 copies/ml
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Mainly clinical - epidemiological and seasonal setting

7. What is the Tx of cryptococcal meninngitis
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Cd4 count
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
ELISA and western blot of synovial fluid.

8. damae that is about to occur?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
HIV viral load
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

9. What is tx for herpes zoster
Every 3-4 hours to determine appropritate time to start HAART
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Others lesions are ring enhancing and have mass effect while PML don't
Acyclovir

10. How to dx IM?
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.
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
When cd4 count falls below 200. 2p in pcp =200

11. low grade fever - maculopapular rash - lymphadenopathy
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Pegylated interferon and lamivudine
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

12. How to give postexposure prophylaxis for HIV
Ampicillin-sublactam; most bites contain eikenella
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
ELISA and western blot of synovial fluid.

13. causative organisms of uti
Td every 10 years - tdap once before 65 and after 65
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
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
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

14. When to tx asymptomatic bacteriurea >100 -000?
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Pt who have been treated before for latent TB
Either TB or aspergillosis
Pregnacy - urologic procedure - hip arthoplastu

15. How to dx IM?
Monospot test which screen heteropile ab that agglutinate horse rbc
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
Mainly clinical - epidemiological and seasonal setting
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

16. clinical manifestation of mucomycosis
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Similar pathophysiology as ITP - tx zidovudine
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

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

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18. What is the pathophysiology of Meningococcal meningitis?
PML; focal neurological deficit like MM; no specific tx; regress with HAART
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

19. what if monospot test is neg in IM?
Similar pathophysiology as ITP - tx zidovudine
ELISA and western blot of synovial fluid.
Blastomycosis
Do EBV antibody test

20. acute onset +rusty sputum
Similar pathophysiology as ITP - tx zidovudine
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

21. When to give prophylaxis against MAC
Td every 10 years - tdap once before 65 and after 65
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
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

22. oligodendrocyte with intranuclear inclusion and demyelination in HIV 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
PML; focal neurological deficit like MM; no specific tx; regress with HAART
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
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

23. How to tx IM?
Mainly clinical - epidemiological and seasonal setting
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

24. how HAART therapy affects HIV viral loads?
Others lesions are ring enhancing and have mass effect while PML don't
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Within 6 months viral load will be <50

25. How to differentiate gonococcal and nongonoccal urethritis?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

26. What is tetanus - diptheria - pertusis recommendation?
Td every 10 years - tdap once before 65 and after 65
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
<5000 copies/ml
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

27. INH
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Oropharyngeal secretions; hence named as kissing disease
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

28. how CMV presents in immunocompromised patients
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
HBIG hep B immunoglobulin
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

29. aspergillosis
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Voriconazol. mycetoma-surgical removal
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

30. antibiotic with good prostate penetration?
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
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

31. When not to tx asymptomatic bacteriura?
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
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Non pregnant premanopausal - elderly - dm - sci - chronic foley

32. How to tx pseudomonas?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Voriconazol. mycetoma-surgical removal
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Mainly clinical - epidemiological and seasonal setting

33. infiltrate in upper lobe of lung?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Either TB or aspergillosis
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

34. INH
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
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
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. how im is transmitted?
Similar pathophysiology as ITP - tx zidovudine
Oropharyngeal secretions; hence named as kissing disease
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
Every 3-4 hours to determine appropritate time to start HAART

36. after recent exposure - negative ELISA - How to confirm?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Td every 10 years - tdap once before 65 and after 65
Aortic valve; endocardiits of AR p/w AV block and LBBB

37. rifampin
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Voriconazol. mycetoma-surgical removal
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

38. Tx of choice for human bites
6-12 weeks
Ampicillin-sublactam; most bites contain eikenella
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
Postcoital voiding - increased intake of cranberry juice

39. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
HBIG hep B immunoglobulin
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
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

40. What are indicators for progression of HIV
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Viral load and 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

41. How to confirm chlamydia infection?
AA gradient >35 or Po2 <70
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
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

42. acute febrile reaction develops after starting penicilin tx to syphilis patient
Td every 10 years - tdap once before 65 and after 65
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.
Every 3-4 hours to determine appropritate time to start HAART
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

43. How to dx progressive multifocal leukoencephalopathy
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Vaccine titer >10mU/ml

44. How often HIV postiive patients CD4 count needs to be evaluated?
Every 3-4 hours to determine appropritate time to start HAART
HIV viral load
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

45. What is the classic signs of nec fasc?
Pt who have been treated before for latent TB
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
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

46. What is the Tx of STD uretheritis?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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

47. 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
Oropharyngeal secretions; hence named as kissing disease
Clostridium perfringens after penetrative injuries/wounds
HIV viral load

48. How to differentiate different types of necrotizing fascitis?
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
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
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Aortic valve; endocardiits of AR p/w AV block and LBBB

49. what parameters increases risk of neurosyphilis in HIV patient
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
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.
Cd4 count
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

50. pathophysiology of toxic shock syndrom?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads