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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. reddish colored papules with central umbilication in HIV or immunocompromised patient
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
Voriconazol. mycetoma-surgical removal
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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

2. When not to tx asymptomatic bacteriura?
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
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

3. hypertension in children
Vaccine titer >10mU/ml
Bronchoalveolar washing and transbronchial biopsy
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

4. What is the pathophysiology of Meningococcal meningitis?
<500 copies/ml
Ampicillin-sublactam; most bites contain eikenella
ELISA and western blot of synovial fluid.
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

5. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Either TB or aspergillosis
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

6. How to tx chronic hep B
Clostridium perfringens after penetrative injuries/wounds
Pegylated interferon and lamivudine
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
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

7. What is used for prophylaxis against meningo..meningitis?
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Rifampin600mg q12. or cipro
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

8. How to dx IM?
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
If a sample is ELISA positive - it is tested fro western blot for confirmation

9. What are indicators for progression of HIV
Either TB or aspergillosis
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Viral load and CD4 count
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

10. How to dx adequate response to HBV vaccine
<500 copies/ml
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Vaccine titer >10mU/ml
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

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
Bronchoalveolar washing and transbronchial biopsy
HBIG hep B immunoglobulin
HIV viral load

12. How to differentiate gonococcal and nongonoccal urethritis?
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
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

13. can HIV transmitted through human bite?
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Immune mediated; circulating IgG and IgM to penicillin derivatives
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Pegylated interferon and lamivudine

14. INH
Postcoital voiding - increased intake of cranberry juice
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Monospot test which screen heteropile ab that agglutinate horse rbc
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

15. How to dx progressive multifocal leukoencephalopathy
Every 3-4 hours to determine appropritate time to start HAART
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

16. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Oropharyngeal secretions; hence named as kissing disease
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
HBIG hep B immunoglobulin
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

17. pneumococcal vaccine indication?
Acyclovir
High risk 19-64; 1-2 dose - above 65; one dose
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Cd4 count

18. hypertriglyceridemia in HIV
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
<5000 copies/ml

19. how im is transmitted?
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Oropharyngeal secretions; hence named as kissing disease
Viral load and CD4 count

20. chshould we tx IM with abx (ampicilin) if throat cx is positive?
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
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

21. How to dx cryptococal meninggits
Monospot test which screen heteropile ab that agglutinate horse rbc
If a sample is ELISA positive - it is tested fro western blot for confirmation
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

22. pathophysiology of toxic shock syndrom?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
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

23. what would be viral load after 2-4m of HAART?
Cd4 count
<500 copies/ml
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
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

24. thrombocytopenia in HIV
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
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

25. What is tx for herpes zoster
Acyclovir
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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
Oropharyngeal secretions; hence named as kissing disease

26. what would be viral load after 4 weeks
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
<5000 copies/ml

27. What is the criteria for Spontaneous bact peritonitis
Pegylated interferon and lamivudine
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Td every 10 years - tdap once before 65 and after 65

28. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
6-12 weeks
Pregnacy - urologic procedure - hip arthoplastu
Cd4 count
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

29. What is the mch of ampicillin induced rash in IM
Pregnacy - urologic procedure - hip arthoplastu
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
Immune mediated; circulating IgG and IgM to penicillin derivatives
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

30. How long we tx chronic prostatis?
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
6-12 weeks
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

31. What is the classic signs of nec fasc?
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
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; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

32. What is the prognosis of lyme arthritis?
Ampicillin-sublactam; most bites contain eikenella
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Every 3-4 hours to determine appropritate time to start HAART

33. what if monospot test is neg in IM?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Do EBV antibody test
Clostridium perfringens after penetrative injuries/wounds

34. infiltrate in upper lobe of lung?
Monospot test which screen heteropile ab that agglutinate horse rbc
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Either TB or aspergillosis
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. What is lag time to develop lyme arthritis after exposure to vector
ELISA and western blot of synovial fluid.
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
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

36. How often HIV postiive patients CD4 count needs to be evaluated?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
HIV viral load
Every 3-4 hours to determine appropritate time to start HAART

37. after recent exposure - negative ELISA - How to confirm?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
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
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

38. What is difference between uti relapse versus recurrence?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Ampicillin-sublactam; most bites contain eikenella
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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

39. how CMV presents in immunocompromised patients
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
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
Either TB or aspergillosis
AA gradient >35 or Po2 <70

40. when we see echym gangrenosum?
If a sample is ELISA positive - it is tested fro western blot for confirmation
HIV viral load
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
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

41. What is the Tx of cryptococcal meninngitis
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Immune mediated; circulating IgG and IgM to penicillin derivatives
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

42. acute febrile reaction develops after starting penicilin tx to syphilis patient
Immune mediated; circulating IgG and IgM to penicillin derivatives
Others lesions are ring enhancing and have mass effect while PML don't
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
ELISA; initial visit - 6 - 12 and 24 weeks;

43. which heart valve is closer to ventricular conduction system/
Do EBV antibody test
Aortic valve; endocardiits of AR p/w AV block and LBBB
Clostridium perfringens after penetrative injuries/wounds
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

44. damae that is about to occur?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
HIV viral load
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

45. What are the subjective /objective measure of encephalopathy?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

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

47. How to dx?
Upper lobes; any fibrosis in this area suggestive of latent TB
Mainly clinical - epidemiological and seasonal setting
Rifampin600mg q12. or cipro
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

48. when HIV patient develop pcp?
When cd4 count falls below 200. 2p in pcp =200
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
If a sample is ELISA positive - it is tested fro western blot for confirmation

49. when western blot is done for HIV testing
HIV viral load
Monospot test which screen heteropile ab that agglutinate horse rbc
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
If a sample is ELISA positive - it is tested fro western blot for confirmation

50. low grade fever - maculopapular rash - lymphadenopathy
Acyclovir
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses