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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 tx for herpes zoster
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
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
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Acyclovir

2. after exposure of HIV when antibody testing is performed?
Do EBV antibody test
ELISA; initial visit - 6 - 12 and 24 weeks;
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
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

3. can HIV transmitted through human bite?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
<500 copies/ml
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes

4. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
HIV viral load
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

5. How to tx pcp?
Mainly clinical - epidemiological and seasonal setting
Voriconazol. mycetoma-surgical removal
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Rifampin600mg q12. or cipro

6. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
ELISA; initial visit - 6 - 12 and 24 weeks;
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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

7. How to dx cryptococal meninggits
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Others lesions are ring enhancing and have mass effect while PML don't
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

8. when not to give INH therapy if ppd positive and patient asyptomatic
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Pt who have been treated before for latent TB
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

9. How long abx is given in pseudomonas infection?
Non pregnant premanopausal - elderly - dm - sci - chronic foley
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Acyclovir

10. what would be viral load after 2-4m of HAART?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
<500 copies/ml
6-12 weeks
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

11. 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.
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
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
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

12. how HAART therapy affects HIV viral loads?
Within 6 months viral load will be <50
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Voriconazol. mycetoma-surgical removal

13. hypertension in children
HIV viral load
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

14. Tx of choice for human bites
If a sample is ELISA positive - it is tested fro western blot for confirmation
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Ampicillin-sublactam; most bites contain eikenella

15. How to give postexposure prophylaxis for HIV
Others lesions are ring enhancing and have mass effect while PML don't
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

16. What is the indication of corticosteroid in pcp infection?
PML; focal neurological deficit like MM; no specific tx; regress with HAART
AA gradient >35 or Po2 <70
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
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

17. What is characteristic for dx of rocky mountain spotted fever?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
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

18. What is the criteria for Spontaneous bact peritonitis
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
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

19. reddish colored papules with central umbilication in HIV or immunocompromised patient
If a sample is ELISA positive - it is tested fro western blot for confirmation
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
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
Vaccine titer >10mU/ml

20. How to tx IM?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
If a sample is ELISA positive - it is tested fro western blot for confirmation

21. What is the mch of ampicillin induced rash in IM
Aortic valve; endocardiits of AR p/w AV block and LBBB
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Immune mediated; circulating IgG and IgM to penicillin derivatives

22. When to give abx to prevent recurrent uti
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
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
ELISA and western blot of synovial fluid.
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. low grade fever - maculopapular rash - lymphadenopathy
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
If a sample is ELISA positive - it is tested fro western blot for confirmation
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

24. wisconsin - missisipi - ohio
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
When cd4 count falls below 200. 2p in pcp =200
Bronchoalveolar washing and transbronchial biopsy
Blastomycosis

25. How to confirm chlamydia infection?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
HIV viral load
Every 3-4 hours to determine appropritate time to start HAART
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole

26. worsening of TB after starting HAART in HIV
Vaccine titer >10mU/ml
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
6-12 weeks
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

27. What is the Tx of STD uretheritis?
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
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Reddish orange discoloration of urine - feces - sweat - tears - sputum
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

28. what would be viral load after 4 weeks
<5000 copies/ml
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Do EBV antibody test
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

29. How to dx lyme arthritis?
ELISA and western blot of synovial fluid.
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Do EBV antibody test
Within 6 months viral load will be <50

30. infiltrate in upper lobe of lung?
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Either TB or aspergillosis
Every 3-4 hours to determine appropritate time to start HAART
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

31. What is the Tx of cryptococcal meninngitis
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
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
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

32. INH
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

33. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Upper lobes; any fibrosis in this area suggestive of latent TB
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Bronchoalveolar washing and transbronchial biopsy
Blastomycosis

34. What is lag time to develop lyme arthritis after exposure to vector
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
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
If a sample is ELISA positive - it is tested fro western blot for confirmation
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

35. what parameters increases risk of neurosyphilis in HIV patient
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
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.
ELISA; initial visit - 6 - 12 and 24 weeks;
Mainly clinical - epidemiological and seasonal setting

36. where TB normally affects
AA gradient >35 or Po2 <70
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
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
Upper lobes; any fibrosis in this area suggestive of latent TB

37. How to tx pseudomonas?
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
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Rifampin600mg q12. or cipro

38. aspergillosis
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Voriconazol. mycetoma-surgical removal

39. how im is transmitted?
Oropharyngeal secretions; hence named as kissing disease
HBIG hep B immunoglobulin
<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

40. foot infections in DM
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
<500 copies/ml
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

41. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

42. What are the behavioral interventions decrease the risk of UTI
Postcoital voiding - increased intake of cranberry juice
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Non pregnant premanopausal - elderly - dm - sci - chronic foley

43. What is the prognosis of lyme arthritis?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
HBIG hep B immunoglobulin
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

44. How long we tx chronic prostatis?
6-12 weeks
Postcoital voiding - increased intake of cranberry juice
Pegylated interferon and lamivudine
Every 3-4 hours to determine appropritate time to start HAART

45. when western blot is done for HIV testing
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
If a sample is ELISA positive - it is tested fro western blot for confirmation
Within 6 months viral load will be <50
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

46. What are indicators for progression of HIV
Every 3-4 hours to determine appropritate time to start HAART
Viral load and CD4 count
<500 copies/ml
Td every 10 years - tdap once before 65 and after 65

47. acute febrile reaction develops after starting penicilin tx to syphilis patient
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Upper lobes; any fibrosis in this area suggestive of latent TB
ELISA; initial visit - 6 - 12 and 24 weeks;
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

48. how CMV presents in immunocompromised patients
Rifampin600mg q12. or cipro
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Clostridium perfringens after penetrative injuries/wounds

49. thrombocytopenia in HIV
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Similar pathophysiology as ITP - tx zidovudine
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Upper lobes; any fibrosis in this area suggestive of latent TB

50. which heart valve is closer to ventricular conduction system/
Aortic valve; endocardiits of AR p/w AV block and LBBB
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil