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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. after recent exposure - negative ELISA - How to confirm?
Blastomycosis
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

2. INH
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
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HBIG hep B immunoglobulin

3. How to tx pcp?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
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
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

4. How to tx pseudomonas?
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Upper lobes; any fibrosis in this area suggestive of latent TB
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

5. When to tx asymptomatic bacteriurea >100 -000?
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
Rifampin600mg q12. or cipro
Ampicillin-sublactam; most bites contain eikenella
Pregnacy - urologic procedure - hip arthoplastu

6. What is the Tx of STD uretheritis?
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Within 6 months viral load will be <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
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

7. How to tx IM?
Similar pathophysiology as ITP - tx zidovudine
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid

8. pathophysiology of toxic shock syndrom?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Postcoital voiding - increased intake of cranberry juice
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

9. patient is taking inhaled corticosteroid for asthma - now p/w oral candidiasis
Non pregnant premanopausal - elderly - dm - sci - chronic foley
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
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Clostridium perfringens after penetrative injuries/wounds

10. When not to tx asymptomatic bacteriura?
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
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
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

11. What is tetanus - diptheria - pertusis recommendation?
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)
Td every 10 years - tdap once before 65 and after 65
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

12. causative organisms of uti
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

13. How long we tx chronic prostatis?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
6-12 weeks
Td every 10 years - tdap once before 65 and after 65

14. what parameters increases risk of neurosyphilis in HIV patient
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
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.

15. What is the indication of corticosteroid in pcp infection?
Oropharyngeal secretions; hence named as kissing disease
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
Similar pathophysiology as ITP - tx zidovudine
AA gradient >35 or Po2 <70

16. What is used for prophylaxis against meningo..meningitis?
Rifampin600mg q12. or cipro
If a sample is ELISA positive - it is tested fro western blot for confirmation
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.
Ampicillin-sublactam; most bites contain eikenella

17. how im is transmitted?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Oropharyngeal secretions; hence named as kissing disease
Cd4 count
HIV viral load

18. wisconsin - missisipi - ohio
Blastomycosis
Vaccine titer >10mU/ml
HIV viral load
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

19. When to tx influenza with antiviral therapy?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
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
When cd4 count falls below 200. 2p in pcp =200
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

20. when we see echym gangrenosum?
<5000 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
High risk 19-64; 1-2 dose - above 65; one dose
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

21. What are indicators for progression of HIV
Viral load and CD4 count
HIV viral load
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

22. What is the pathophysiology of Meningococcal meningitis?
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.
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

23. foot infections in DM
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
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

24. HIV patient having fat deposition on back of neck and abdomen - like cushing
Pt who have been treated before for latent TB
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

25. what would be viral load after 2-4m of HAART?
Acyclovir
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
<500 copies/ml
Non pregnant premanopausal - elderly - dm - sci - chronic foley

26. Tx of choice for human bites
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Vaccine titer >10mU/ml
Ampicillin-sublactam; most bites contain eikenella
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

27. aspergillosis
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Voriconazol. mycetoma-surgical removal
Others lesions are ring enhancing and have mass effect while PML don't
Non pregnant premanopausal - elderly - dm - sci - chronic foley

28. infiltrate in upper lobe of lung?
<5000 copies/ml
Either TB or aspergillosis
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

29. What is lag time to develop lyme arthritis after exposure to vector
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
When cd4 count falls below 200. 2p in pcp =200

30. drugs work well on hypertriglyceridia?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Cd4 count
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

31. rifampin
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
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Reddish orange discoloration of urine - feces - sweat - tears - sputum

32. Do we need to give vaccine or immunoglobulin for rabies exposure in previously vaccinated person?
Ampicillin-sublactam; most bites contain eikenella
Do EBV antibody test
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

33. INH
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Bronchoalveolar washing and transbronchial biopsy
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

34. which heart valve is closer to ventricular conduction system/
Pegylated interferon and lamivudine
Aortic valve; endocardiits of AR p/w AV block and LBBB
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

35. How to dx lyme arthritis?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Bronchoalveolar washing and transbronchial biopsy
ELISA and western blot of synovial fluid.
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

36. How to dx adequate response to HBV vaccine
Vaccine titer >10mU/ml
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
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.

37. What is the Tx of cryptococcal meninngitis
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
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
6-12 weeks

38. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Either TB or aspergillosis
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
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
<5000 copies/ml

39. thrombocytopenia in HIV
Vaccine titer >10mU/ml
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Similar pathophysiology as ITP - tx zidovudine

40. when HIV patient develop pcp?
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
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
When cd4 count falls below 200. 2p in pcp =200

41. What are the behavioral interventions decrease the risk of UTI
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
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.
Postcoital voiding - increased intake of cranberry juice
Blastomycosis

42. hypertension in children
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
<500 copies/ml
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Others lesions are ring enhancing and have mass effect while PML don't

43. what would be viral load after 4 weeks
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Monospot test which screen heteropile ab that agglutinate horse rbc
Need lumbar puncture to relieve pressure; they have high opening pressure >350
<5000 copies/ml

44. How to dx IM?
Monospot test which screen heteropile ab that agglutinate horse rbc
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

45. acute febrile reaction develops after starting penicilin tx to syphilis patient
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
HBIG hep B immunoglobulin
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

46. What is characteristic for dx of rocky mountain spotted fever?
If a sample is ELISA positive - it is tested fro western blot for confirmation
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Ampicillin-sublactam; most bites contain eikenella
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

47. how CMV presents in immunocompromised patients
Pregnacy - urologic procedure - hip arthoplastu
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Bronchoalveolar washing and transbronchial biopsy

48. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
<500 copies/ml
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
6-12 weeks

49. How to dx progressive multifocal leukoencephalopathy
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Cd4 count

50. antibiotic with good prostate penetration?
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Pregnacy - urologic procedure - hip arthoplastu
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
<500 copies/ml