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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?
Mainly clinical - epidemiological and seasonal setting
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Within 6 months viral load will be <50

2. gas gangrene
Clostridium perfringens after penetrative injuries/wounds
Every 3-4 hours to determine appropritate time to start HAART
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

3. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Mainly clinical - epidemiological and seasonal setting
Td every 10 years - tdap once before 65 and after 65
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Ampicillin-sublactam; most bites contain eikenella

4. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Monospot test which screen heteropile ab that agglutinate horse rbc
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
ELISA; initial visit - 6 - 12 and 24 weeks;

5. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Mainly clinical - epidemiological and seasonal setting
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

6. What is used for prophylaxis against meningo..meningitis?
Rifampin600mg q12. or cipro
Immune mediated; circulating IgG and IgM to penicillin derivatives
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

7. rifampin
Vaccine titer >10mU/ml
Acyclovir
Reddish orange discoloration of urine - feces - sweat - tears - sputum
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

8. when western blot is done for HIV testing
Others lesions are ring enhancing and have mass effect while PML don't
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.
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
If a sample is ELISA positive - it is tested fro western blot for confirmation

9. when we see echym gangrenosum?
Clostridium perfringens after penetrative injuries/wounds
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

10. How to tx IM?
Upper lobes; any fibrosis in this area suggestive of latent TB
6-12 weeks
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
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

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

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12. dame that has already occurred
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Cd4 count
Pegylated interferon and lamivudine

13. INH
Bronchoalveolar washing and transbronchial biopsy
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
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
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

14. Tx of choice for human bites
Ampicillin-sublactam; most bites contain eikenella
High risk 19-64; 1-2 dose - above 65; one dose
When cd4 count falls below 200. 2p in pcp =200
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

15. acute onset +rusty sputum
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.
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Every 3-4 hours to determine appropritate time to start HAART
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

16. How to tx pcp?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

17. aspergillosis
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Voriconazol. mycetoma-surgical removal
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
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

18. What is the classic signs of nec fasc?
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Blastomycosis
High risk 19-64; 1-2 dose - above 65; one dose

19. What is the prognosis of lyme arthritis?
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
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
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

20. How to tx pseudomonas?
Voriconazol. mycetoma-surgical removal
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

21. How to dx bacterial meningitis from CSF study?

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22. HIV patient having fat deposition on back of neck and abdomen - like cushing
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
When cd4 count falls below 200. 2p in pcp =200
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

23. What are indicators for progression of HIV
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Viral load and CD4 count
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
HIV viral load

24. how CMV presents in immunocompromised patients
Immune mediated; circulating IgG and IgM to penicillin derivatives
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Td every 10 years - tdap once before 65 and after 65

25. How to dx IM?
Clostridium perfringens after penetrative injuries/wounds
Monospot test which screen heteropile ab that agglutinate horse rbc
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
<500 copies/ml

26. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Oropharyngeal secretions; hence named as kissing disease

27. How long we tx chronic prostatis?
6-12 weeks
Clostridium perfringens after penetrative injuries/wounds
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

28. drugs work well on hypertriglyceridia?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Every 3-4 hours to determine appropritate time to start HAART
Voriconazol. mycetoma-surgical removal
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

29. where TB normally affects
Vaccine titer >10mU/ml
Upper lobes; any fibrosis in this area suggestive of latent TB
ELISA; initial visit - 6 - 12 and 24 weeks;
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

30. How to tx chronic hep B
Pegylated interferon and lamivudine
High risk 19-64; 1-2 dose - above 65; one dose
Vaccine titer >10mU/ml
Pt who have been treated before for latent TB

31. after exposure of HIV when antibody testing is performed?
ELISA; initial visit - 6 - 12 and 24 weeks;
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

32. When to tx influenza with antiviral therapy?
Every 3-4 hours to determine appropritate time to start HAART
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
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

33. What is the indication of corticosteroid in pcp infection?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
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
AA gradient >35 or Po2 <70
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

34. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
Aortic valve; endocardiits of AR p/w AV block and LBBB
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.
High risk 19-64; 1-2 dose - above 65; one dose
PML; focal neurological deficit like MM; no specific tx; regress with HAART

35. worsening of TB after starting HAART in HIV
Immune mediated; circulating IgG and IgM to penicillin derivatives
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Either TB or aspergillosis

36. How to dx progressive multifocal leukoencephalopathy
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Either TB or aspergillosis

37. When to tx asymptomatic bacteriurea >100 -000?
<5000 copies/ml
ELISA and western blot of synovial fluid.
Pregnacy - urologic procedure - hip arthoplastu
Acyclovir

38. acute febrile reaction develops after starting penicilin tx to syphilis 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
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Ampicillin-sublactam; most bites contain eikenella

39. when not to give INH therapy if ppd positive and patient asyptomatic
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Cd4 count
Upper lobes; any fibrosis in this area suggestive of latent TB
Pt who have been treated before for latent TB

40. How to dx lyme arthritis?
Postcoital voiding - increased intake of cranberry juice
Reddish orange discoloration of urine - feces - sweat - tears - sputum
ELISA and western blot of synovial fluid.
If a sample is ELISA positive - it is tested fro western blot for confirmation

41. what would be viral load after 2-4m of HAART?
Rifampin600mg q12. or cipro
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
<500 copies/ml
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

42. pneumococcal vaccine indication?
High risk 19-64; 1-2 dose - above 65; one dose
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.
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

43. low grade fever - maculopapular rash - lymphadenopathy
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Monospot test which screen heteropile ab that agglutinate horse rbc
6-12 weeks
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

44. When not to tx asymptomatic bacteriura?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
If a sample is ELISA positive - it is tested fro western blot for confirmation
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
Non pregnant premanopausal - elderly - dm - sci - chronic foley

45. How to confirm chlamydia infection?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Blastomycosis
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
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

46. How to dx IM?
ELISA; initial visit - 6 - 12 and 24 weeks;
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
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
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

47. antibiotic with good prostate penetration?
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
Oropharyngeal secretions; hence named as kissing disease
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

48. What is difference between uti relapse versus recurrence?
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
Need lumbar puncture to relieve pressure; they have high opening pressure >350
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

49. clinical manifestation of mucomycosis
<500 copies/ml
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

50. When to give abx to prevent recurrent uti
Within 6 months viral load will be <50
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
<5000 copies/ml