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USMLE Step3 Infectious Disease

Subjects : health-sciences, usmle-step-3

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Answer 50 questions in 15 minutes.
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1. What are indicators for progression of HIV
Viral load and CD4 count
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
Acyclovir

2. When to tx asymptomatic bacteriurea >100 -000?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Pregnacy - urologic procedure - hip arthoplastu
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

3. How to dx lyme arthritis?
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Ampicillin-sublactam; most bites contain eikenella
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
ELISA and western blot of synovial fluid.

4. What is the pathophysiology of Meningococcal meningitis?
ELISA; initial visit - 6 - 12 and 24 weeks;
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Upper lobes; any fibrosis in this area suggestive of latent TB
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

5. How long we tx chronic prostatis?
Every 3-4 hours to determine appropritate time to start HAART
6-12 weeks
AA gradient >35 or Po2 <70
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

6. clinical manifestation of mucomycosis
Ampicillin-sublactam; most bites contain eikenella
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

7. acute febrile reaction develops after starting penicilin tx to syphilis patient
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Vaccine titer >10mU/ml
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Ampicillin-sublactam; most bites contain eikenella

8. how CMV presents in immunocompromised patients
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
AA gradient >35 or Po2 <70
6-12 weeks
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

9. foot infections in DM
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
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 -
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

10. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
AA gradient >35 or Po2 <70
Postcoital voiding - increased intake of cranberry juice
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Upper lobes; any fibrosis in this area suggestive of latent TB

11. What is lag time to develop lyme arthritis after exposure to vector
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
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
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
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

12. gas gangrene
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Clostridium perfringens after penetrative injuries/wounds
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.

13. rifampin
AA gradient >35 or Po2 <70
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Reddish orange discoloration of urine - feces - sweat - tears - sputum

14. How to differentiate gonococcal and nongonoccal urethritis?
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
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
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
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

15. What is tetanus - diptheria - pertusis recommendation?
Upper lobes; any fibrosis in this area suggestive of latent TB
<5000 copies/ml
ELISA; initial visit - 6 - 12 and 24 weeks;
Td every 10 years - tdap once before 65 and after 65

16. hypertriglyceridemia in HIV
<5000 copies/ml
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

17. INH
ELISA; initial visit - 6 - 12 and 24 weeks;
Do EBV antibody test
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

18. reddish colored papules with central umbilication in HIV or immunocompromised patient
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
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
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

19. What are the behavioral interventions decrease the risk of UTI
Postcoital voiding - increased intake of cranberry juice
Td every 10 years - tdap once before 65 and after 65
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
<500 copies/ml

20. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Upper lobes; any fibrosis in this area suggestive of latent TB
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Non pregnant premanopausal - elderly - dm - sci - chronic foley

21. How to tx pseudomonas?
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

22. what would be viral load after 4 weeks
<5000 copies/ml
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Clostridium perfringens after penetrative injuries/wounds
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

23. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Pt who have been treated before for latent TB
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
HBIG hep B immunoglobulin

24. What are the subjective /objective measure of encephalopathy?
Postcoital voiding - increased intake of cranberry juice
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
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Blastomycosis

25. where TB normally affects
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Blastomycosis
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Upper lobes; any fibrosis in this area suggestive of latent TB

26. How to tx TSS?
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
Acyclovir
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Within 6 months viral load will be <50

27. when HIV patient develop pcp?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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
When cd4 count falls below 200. 2p in pcp =200

28. How to differentiate different types of necrotizing fascitis?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
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
Cd4 count

29. hypertension in children
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Oropharyngeal secretions; hence named as kissing disease

30. What is the Tx of cryptococcal meninngitis
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
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

31. which heart valve is closer to ventricular conduction system/
Aortic valve; endocardiits of AR p/w AV block and LBBB
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

32. pathophysiology of toxic shock syndrom?
Reddish orange discoloration of urine - feces - sweat - tears - sputum
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Blastomycosis

33. what would be viral load after 2-4m of HAART?
<500 copies/ml
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
HIV viral load

34. infiltrate in upper lobe of lung?
AA gradient >35 or Po2 <70
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Either TB or aspergillosis

35. How to dx IM?
Oropharyngeal secretions; hence named as kissing disease
High risk 19-64; 1-2 dose - above 65; one dose
Monospot test which screen heteropile ab that agglutinate horse rbc
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

36. How to dx bacterial meningitis from CSF study?

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37. drugs work well on hypertriglyceridia?
Every 3-4 hours to determine appropritate time to start HAART
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
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 viral load

38. What is used for prophylaxis against meningo..meningitis?
Rifampin600mg q12. or cipro
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Pregnacy - urologic procedure - hip arthoplastu
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

39. can HIV transmitted through human bite?
6-12 weeks
Oropharyngeal secretions; hence named as kissing disease
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Voriconazol. mycetoma-surgical removal

40. chshould we tx IM with abx (ampicilin) if throat cx is positive?
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Similar pathophysiology as ITP - tx zidovudine
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash

41. acute onset +rusty sputum
Similar pathophysiology as ITP - tx zidovudine
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure

42. after recent exposure - negative ELISA - How to confirm?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
Reddish orange discoloration of urine - feces - sweat - tears - sputum

43. How to dx cryptococal meninggits
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

44. What is the classic signs of nec fasc?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
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
AA gradient >35 or Po2 <70

45. low grade fever - maculopapular rash - lymphadenopathy
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

46. When not to tx asymptomatic bacteriura?
Either TB or aspergillosis
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
Non pregnant premanopausal - elderly - dm - sci - chronic foley
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.

47. worsening of TB after starting HAART in HIV
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx

48. what parameters increases risk of neurosyphilis in HIV patient
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.
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
ELISA and western blot of synovial fluid.
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

49. 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
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
When cd4 count falls below 200. 2p in pcp =200
Clostridium perfringens after penetrative injuries/wounds

50. when we see echym gangrenosum?
PML; focal neurological deficit like MM; no specific tx; regress with HAART
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
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
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease

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USMLE Step3 Infectious Disease

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