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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. What is the classic signs of nec fasc?
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
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Vaccine titer >10mU/ml
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

2. HIV patient having fat deposition on back of neck and abdomen - like cushing
6-12 weeks
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

3. How to dx lyme arthritis?
Rifampin600mg q12. or cipro
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Oropharyngeal secretions; hence named as kissing disease
ELISA and western blot of synovial fluid.

4. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
ELISA; initial visit - 6 - 12 and 24 weeks;
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

5. low grade fever - maculopapular rash - lymphadenopathy
Aortic valve; endocardiits of AR p/w AV block and LBBB
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

6. What is the criteria for Spontaneous bact peritonitis
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
High risk 19-64; 1-2 dose - above 65; one dose
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
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

7. causative organisms of uti
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

8. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Vaccine titer >10mU/ml
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Every 3-4 hours to determine appropritate time to start HAART
Others lesions are ring enhancing and have mass effect while PML don't

9. damae that is about to occur?
If a sample is ELISA positive - it is tested fro western blot for confirmation
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
HIV viral load

10. systolic HTN in elderly
ELISA and western blot of synovial fluid.
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

11. How often viral load is monitored after HAART?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

12. clinical manifestation of mucomycosis
PML; focal neurological deficit like MM; no specific tx; regress with HAART
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

13. What is fatal consequence of RMSF?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
ELISA and western blot of synovial fluid.
6-12 weeks

14. What is the prognosis of lyme arthritis?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
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
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

15. when HIV patient develop pcp?
Oropharyngeal secretions; hence named as kissing disease
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Postcoital voiding - increased intake of cranberry juice
When cd4 count falls below 200. 2p in pcp =200

16. How to dx adequate response to HBV vaccine
Vaccine titer >10mU/ml
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Either TB or aspergillosis
Cd4 count

17. What are the behavioral interventions decrease the risk of UTI
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Postcoital voiding - increased intake of cranberry juice
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

18. What is the Tx of STD uretheritis?
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
Others lesions are ring enhancing and have mass effect while PML don't
Viral load and CD4 count
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

19. thrombocytopenia in HIV
Similar pathophysiology as ITP - tx zidovudine
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
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

20. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
HBIG hep B immunoglobulin
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
PML; focal neurological deficit like MM; no specific tx; regress with HAART

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

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22. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
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
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Pt who have been treated before for latent TB

23. 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
Pregnacy - urologic procedure - hip arthoplastu
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
<5000 copies/ml

24. after exposure of HIV when antibody testing is performed?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Mainly clinical - epidemiological and seasonal setting
ELISA; initial visit - 6 - 12 and 24 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

25. When to tx asymptomatic bacteriurea >100 -000?
Pegylated interferon and lamivudine
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Pregnacy - urologic procedure - hip arthoplastu

26. What is difference between uti relapse versus recurrence?
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
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
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 lag time to develop lyme arthritis after exposure to vector
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Pregnacy - urologic procedure - hip arthoplastu
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

28. pneumococcal vaccine indication?
High risk 19-64; 1-2 dose - above 65; one dose
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
PML; focal neurological deficit like MM; no specific tx; regress with HAART

29. What is used for prophylaxis against meningo..meningitis?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
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
Rifampin600mg q12. or cipro
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

30. What is the mch of ampicillin induced rash in IM
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Voriconazol. mycetoma-surgical removal
Immune mediated; circulating IgG and IgM to penicillin derivatives
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

31. when western blot is done for HIV testing
Mainly clinical - epidemiological and seasonal setting
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
If a sample is ELISA positive - it is tested fro western blot for confirmation

32. How often HIV postiive patients CD4 count needs to be evaluated?
<5000 copies/ml
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
High risk 19-64; 1-2 dose - above 65; one dose
Every 3-4 hours to determine appropritate time to start HAART

33. reddish colored papules with central umbilication in HIV or immunocompromised patient
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
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
Cd4 count
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

34. 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
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Cd4 count

35. when not to give INH therapy if ppd positive and patient asyptomatic
Pt who have been treated before for latent TB
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
PML; focal neurological deficit like MM; no specific tx; regress with HAART

36. When to tx influenza with antiviral therapy?
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
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
Voriconazol. mycetoma-surgical removal
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

37. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
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
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
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

38. How to tx IM?
Td every 10 years - tdap once before 65 and after 65
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Mainly clinical - epidemiological and seasonal setting

39. How to confirm dx if pcp?
Pt who have been treated before for latent TB
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
Within 6 months viral load will be <50
Bronchoalveolar washing and transbronchial biopsy

40. How to differentiate different types of necrotizing fascitis?
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Non pregnant premanopausal - elderly - dm - sci - chronic foley
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
ELISA; initial visit - 6 - 12 and 24 weeks;

41. How to tx pcp?
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Voriconazol. mycetoma-surgical removal
Postcoital voiding - increased intake of cranberry juice
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

42. How long we tx chronic prostatis?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
6-12 weeks
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

43. drugs work well on hypertriglyceridia?
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
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Mainly clinical - epidemiological and seasonal setting

44. aspergillosis
<5000 copies/ml
Voriconazol. mycetoma-surgical removal
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

45. How to dx cryptococal meninggits
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Cd4 count
When cd4 count falls below 200. 2p in pcp =200
Do EBV antibody test

46. 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
HIV viral load
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

47. How to dx IM?
Vaccine titer >10mU/ml
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

48. what if monospot test is neg in IM?
Do EBV antibody test
Postcoital voiding - increased intake of cranberry juice
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Mainly clinical - epidemiological and seasonal setting

49. How long abx is given in pseudomonas infection?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Ampicillin-sublactam; most bites contain eikenella
Rifampin600mg q12. or cipro

50. dame that has already occurred
Mainly clinical - epidemiological and seasonal setting
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
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