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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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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. hypertriglyceridemia in HIV
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Mainly clinical - epidemiological and seasonal setting
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Blastomycosis

2. What is used for prophylaxis against meningo..meningitis?
ELISA; initial visit - 6 - 12 and 24 weeks;
Rifampin600mg q12. or cipro
Immune mediated; circulating IgG and IgM to penicillin derivatives
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

3. When to tx influenza with antiviral therapy?
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
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
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

4. can HIV transmitted through human bite?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Every 3-4 hours to determine appropritate time to start HAART
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

5. acute febrile reaction develops after starting penicilin tx to syphilis patient
Clostridium perfringens after penetrative injuries/wounds
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
Need lumbar puncture to relieve pressure; they have high opening pressure >350

6. when not to give INH therapy if ppd positive and patient asyptomatic
Pt who have been treated before for latent TB
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
6-12 weeks
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

7. when HIV patient develop pcp?
Oropharyngeal secretions; hence named as kissing disease
When cd4 count falls below 200. 2p in pcp =200
Monospot test which screen heteropile ab that agglutinate horse rbc
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

8. How to tx chronic hep B
Acyclovir
Pegylated interferon and lamivudine
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

9. What is tetanus - diptheria - pertusis recommendation?
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Td every 10 years - tdap once before 65 and after 65

10. where TB normally affects
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
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
Upper lobes; any fibrosis in this area suggestive of latent TB
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

11. When to give prophylaxis against MAC
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Similar pathophysiology as ITP - tx zidovudine

12. drugs work well on hypertriglyceridia?
Do EBV antibody test
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

13. What is tx for herpes zoster
Acyclovir
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

14. gas gangrene
Clostridium perfringens after penetrative injuries/wounds
Oropharyngeal secretions; hence named as kissing disease
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

15. How often viral load is monitored after HAART?
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Pregnacy - urologic procedure - hip arthoplastu
Vaccine titer >10mU/ml
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

16. What is difference between uti relapse versus recurrence?
Do EBV antibody test
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
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Immune mediated; circulating IgG and IgM to penicillin derivatives

17. infiltrate in upper lobe of lung?
ELISA and western blot of synovial fluid.
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Either TB or aspergillosis

18. When not to tx asymptomatic bacteriura?
When cd4 count falls below 200. 2p in pcp =200
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Non pregnant premanopausal - elderly - dm - sci - chronic foley

19. 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
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
High risk 19-64; 1-2 dose - above 65; one dose
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

20. pneumococcal vaccine indication?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Bronchoalveolar washing and transbronchial biopsy
High risk 19-64; 1-2 dose - above 65; one dose

21. How to tx TSS?
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Need lumbar puncture to relieve pressure; they have high opening pressure >350
ELISA; initial visit - 6 - 12 and 24 weeks;

22. acute onset +rusty sputum
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Clostridium perfringens after penetrative injuries/wounds

23. causative organisms of uti
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Pt who have been treated before for latent TB

24. hypertension in children
Oropharyngeal secretions; hence named as kissing disease
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Pt who have been treated before for latent TB

25. INH
Td every 10 years - tdap once before 65 and after 65
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Bronchoalveolar washing and transbronchial biopsy
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50

26. How to dx adequate response to HBV vaccine
Vaccine titer >10mU/ml
Monospot test which screen heteropile ab that agglutinate horse rbc
PML; focal neurological deficit like MM; no specific tx; regress with HAART
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

27. What are indicators for progression of HIV
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.
Viral load and CD4 count
Rifampin600mg q12. or cipro

28. damae that is about to occur?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
HIV viral load
Upper lobes; any fibrosis in this area suggestive of latent TB

29. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Vaccine titer >10mU/ml
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
HBIG hep B immunoglobulin
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

30. How to tx pcp?
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
High risk 19-64; 1-2 dose - above 65; one dose
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Either TB or aspergillosis

31. what would be viral load after 2-4m of HAART?
<500 copies/ml
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Others lesions are ring enhancing and have mass effect while PML don't
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

32. What is the prognosis of lyme arthritis?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

33. thrombocytopenia in HIV
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Acyclovir
Similar pathophysiology as ITP - tx zidovudine

34. clinical manifestation of mucomycosis
HIV viral load
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Within 6 months viral load will be <50

35. INH
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.
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Pt who have been treated before for latent TB

36. How to dx bacterial meningitis from CSF study?

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37. What is the mch of ampicillin induced rash in IM
Immune mediated; circulating IgG and IgM to penicillin derivatives
ELISA and western blot of synovial fluid.
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

38. how HAART therapy affects HIV viral loads?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Td every 10 years - tdap once before 65 and after 65
Every 3-4 hours to determine appropritate time to start HAART
Within 6 months viral load will be <50

39. how CMV presents in immunocompromised patients
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
HBIG hep B immunoglobulin
Oropharyngeal secretions; hence named as kissing disease
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

40. antibiotic with good prostate penetration?
ELISA; initial visit - 6 - 12 and 24 weeks;
HBIG hep B immunoglobulin
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Pregnacy - urologic procedure - hip arthoplastu

41. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with 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.
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

42. What are the behavioral interventions decrease the risk of UTI
Within 6 months viral load will be <50
Postcoital voiding - increased intake of cranberry juice
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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

43. wisconsin - missisipi - ohio
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.
Blastomycosis
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
If a sample is ELISA positive - it is tested fro western blot for confirmation

44. 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.
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Aortic valve; endocardiits of AR p/w AV block and LBBB
Cd4 count

45. What are the subjective /objective measure of encephalopathy?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
PML; focal neurological deficit like MM; no specific tx; regress with HAART

46. What is the criteria for Spontaneous bact peritonitis
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Ampicillin-sublactam; most bites contain eikenella
HBIG hep B immunoglobulin

47. what would be viral load after 4 weeks
Pegylated interferon and lamivudine
<5000 copies/ml
Oropharyngeal secretions; hence named as kissing disease
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

48. aspergillosis
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Others lesions are ring enhancing and have mass effect while PML don't
Td every 10 years - tdap once before 65 and after 65
Voriconazol. mycetoma-surgical removal

49. foot infections in DM
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
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

50. What is the classic signs of nec fasc?
Acyclovir
6-12 weeks
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
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