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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. how HAART therapy affects HIV viral loads?
High risk 19-64; 1-2 dose - above 65; one dose
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Within 6 months viral load will be <50
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

2. after exposure of HIV when antibody testing is performed?
<500 copies/ml
ELISA; initial visit - 6 - 12 and 24 weeks;
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Monospot test which screen heteropile ab that agglutinate horse rbc

3. after recent exposure - negative ELISA - How to confirm?
Pegylated interferon and lamivudine
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
Need lumbar puncture to relieve pressure; they have high opening pressure >350
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

4. low grade fever - maculopapular rash - lymphadenopathy
Within 6 months viral load will be <50
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

5. where TB normally affects
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
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
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
Upper lobes; any fibrosis in this area suggestive of latent TB

6. How often viral load is monitored after HAART?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Others lesions are ring enhancing and have mass effect while PML don't
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

7. What is characteristic for dx of rocky mountain spotted fever?
Monospot test which screen heteropile ab that agglutinate horse rbc
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

8. How to tx TSS?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Bronchoalveolar washing and transbronchial biopsy
Either TB or aspergillosis
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

9. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Immune mediated; circulating IgG and IgM to penicillin derivatives
ELISA and western blot of synovial fluid.

10. What are indicators for progression of HIV
Pegylated interferon and lamivudine
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Either TB or aspergillosis
Viral load and CD4 count

11. foot infections in DM
<5000 copies/ml
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
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

12. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Cd4 count
Bronchoalveolar washing and transbronchial biopsy
Postcoital voiding - increased intake of cranberry juice
HBIG hep B immunoglobulin

13. antibiotic with good prostate penetration?
Oropharyngeal secretions; hence named as kissing disease
Rifampin600mg q12. or cipro
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

14. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Acyclovir
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

15. causative organisms of uti
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Pegylated interferon and lamivudine
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

16. What is tx for herpes zoster
Mainly clinical - epidemiological and seasonal setting
Acyclovir
Upper lobes; any fibrosis in this area suggestive of latent TB
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

17. What is difference between uti relapse versus recurrence?
Others lesions are ring enhancing and have mass effect while PML don't
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
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
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

18. what if monospot test is neg in 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.
Similar pathophysiology as ITP - tx zidovudine
Do EBV antibody test
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

19. when HIV patient develop pcp?
When cd4 count falls below 200. 2p in pcp =200
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Bronchoalveolar washing and transbronchial biopsy

20. What is the prognosis of lyme arthritis?
Either TB or aspergillosis
Within 6 months viral load will be <50
Aortic valve; endocardiits of AR p/w AV block and LBBB
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

21. aspergillosis
PML; focal neurological deficit like MM; no specific tx; regress with HAART
<5000 copies/ml
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Voriconazol. mycetoma-surgical removal

22. What is the pathophysiology of Meningococcal meningitis?
Similar pathophysiology as ITP - tx zidovudine
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

23. what would be viral load after 2-4m of HAART?
<500 copies/ml
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Others lesions are ring enhancing and have mass effect while PML don't
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

24. When to tx asymptomatic bacteriurea >100 -000?
Every 3-4 hours to determine appropritate time to start HAART
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Pregnacy - urologic procedure - hip arthoplastu
Reddish orange discoloration of urine - feces - sweat - tears - sputum

25. How to tx IM?
High risk 19-64; 1-2 dose - above 65; one dose
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Td every 10 years - tdap once before 65 and after 65
ELISA and western blot of synovial fluid.

26. How to dx adequate response to HBV vaccine
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
Vaccine titer >10mU/ml
AA gradient >35 or Po2 <70
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

27. how im is transmitted?
Vaccine titer >10mU/ml
Oropharyngeal secretions; hence named as kissing disease
Pregnacy - urologic procedure - hip arthoplastu
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

28. What is the criteria for Spontaneous bact peritonitis
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
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
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

29. acute onset +rusty sputum
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
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
Blastomycosis
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

30. How to differentiat PML from toxoxplasmosis - cns lymphoma adn brain abscess

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31. When to give prophylaxis against MAC
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Viral load and CD4 count
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
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

32. HIV patient having fat deposition on back of neck and abdomen - like cushing
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
ELISA and western blot of synovial fluid.
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

33. drugs work well on hypertriglyceridia?
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
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; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

34. How to confirm chlamydia infection?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

35. What is used for prophylaxis against meningo..meningitis?
Voriconazol. mycetoma-surgical removal
<500 copies/ml
Rifampin600mg q12. or cipro
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

36. 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
Pegylated interferon and lamivudine
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

37. wisconsin - missisipi - ohio
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
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
AA gradient >35 or Po2 <70
Blastomycosis

38. infiltrate in upper lobe of lung?
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Pt who have been treated before for latent TB
Bronchoalveolar washing and transbronchial biopsy
Either TB or aspergillosis

39. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
PML; focal neurological deficit like MM; no specific tx; regress with HAART
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
Voriconazol. mycetoma-surgical removal
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

40. how CMV presents in immunocompromised patients
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Within 6 months viral load will be <50

41. when western blot is done for HIV testing
If a sample is ELISA positive - it is tested fro western blot for confirmation
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
<500 copies/ml
Pegylated interferon and lamivudine

42. can HIV transmitted through human bite?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Reddish orange discoloration of urine - feces - sweat - tears - sputum

43. What is lag time to develop lyme arthritis after exposure to vector
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Acyclovir

44. How to dx IM?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

45. What is tetanus - diptheria - pertusis recommendation?
Td every 10 years - tdap once before 65 and after 65
If a sample is ELISA positive - it is tested fro western blot for confirmation
Every 3-4 hours to determine appropritate time to start HAART
ELISA and western blot of synovial fluid.

46. How to confirm dx if pcp?
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
Bronchoalveolar washing and transbronchial biopsy
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Need lumbar puncture to relieve pressure; they have high opening pressure >350

47. How to dx progressive multifocal leukoencephalopathy
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Voriconazol. mycetoma-surgical removal
AA gradient >35 or Po2 <70

48. INH
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Others lesions are ring enhancing and have mass effect while PML don't

49. 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
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Upper lobes; any fibrosis in this area suggestive of latent TB

50. acute febrile reaction develops after starting penicilin tx to syphilis patient
AA gradient >35 or Po2 <70
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Aortic valve; endocardiits of AR p/w AV block and LBBB