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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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Match each statement with the correct term.
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1. wisconsin - missisipi - ohio
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
Blastomycosis
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

2. what parameters increases risk of neurosyphilis in HIV patient
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
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.

3. How often viral load is monitored after HAART?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
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
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

4. What are the subjective /objective measure of encephalopathy?
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
Every 3-4 hours to determine appropritate time to start HAART
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

5. What is the mch of ampicillin induced rash in IM
Pegylated interferon and lamivudine
Immune mediated; circulating IgG and IgM to penicillin derivatives
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
Viral load and CD4 count

6. worsening of TB after starting HAART in HIV
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
HBIG hep B immunoglobulin
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Bronchoalveolar washing and transbronchial biopsy

7. drugs work well on hypertriglyceridia?
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
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
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

8. dame that has already occurred
Monospot test which screen heteropile ab that agglutinate horse rbc
Do EBV antibody test
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Cd4 count

9. How to confirm chlamydia infection?
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Pregnacy - urologic procedure - hip arthoplastu
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

10. How long abx is given in pseudomonas infection?
Voriconazol. mycetoma-surgical removal
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
Either TB or aspergillosis
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

11. where TB normally affects
Bronchoalveolar washing and transbronchial biopsy
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
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Upper lobes; any fibrosis in this area suggestive of latent TB

12. What are the behavioral interventions decrease the risk of UTI
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
HBIG hep B immunoglobulin
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Postcoital voiding - increased intake of cranberry juice

13. What is the Tx of cryptococcal meninngitis
Pegylated interferon and lamivudine
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
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
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol

14. What is lag time to develop lyme arthritis after exposure to vector
Do EBV antibody test
HIV RNA PCR assay; there may be small amount of virus that are not detectable in ELISA.
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
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

15. How to dx IM?
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
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
HBIG hep B immunoglobulin

16. after exposure of HIV when antibody testing is performed?
ELISA; initial visit - 6 - 12 and 24 weeks;
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
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

17. How long we tx chronic prostatis?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Voriconazol. mycetoma-surgical removal
HIV viral load
6-12 weeks

18. When to give prophylaxis against MAC
Postcoital voiding - increased intake of cranberry juice
PML; focal neurological deficit like MM; no specific tx; regress with HAART
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma

19. Tx of choice for human bites
Ampicillin-sublactam; most bites contain eikenella
Pt who have been treated before for latent TB
Blastomycosis
High risk 19-64; 1-2 dose - above 65; one dose

20. What is characteristic for dx of rocky mountain spotted fever?
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
HBIG hep B immunoglobulin
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

21. gas gangrene
Immune mediated; circulating IgG and IgM to penicillin derivatives
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
Clostridium perfringens after penetrative injuries/wounds
HBIG hep B immunoglobulin

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

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23. INH
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Td every 10 years - tdap once before 65 and after 65
Ampicillin-sublactam; most bites contain eikenella
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

24. How to confirm dx if pcp?
Pregnacy - urologic procedure - hip arthoplastu
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Bronchoalveolar washing and transbronchial biopsy

25. What is the Tx of STD uretheritis?
Viral load and CD4 count
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Rifampin600mg q12. or cipro
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

26. How to differentiate different types of necrotizing fascitis?
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)
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
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

27. reddish colored papules with central umbilication in HIV or immunocompromised patient
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
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
HBIG hep B immunoglobulin

28. hypertriglyceridemia in HIV
Need lumbar puncture to relieve pressure; they have high opening pressure >350
ELISA; initial visit - 6 - 12 and 24 weeks;
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate
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

29. can HIV transmitted through human bite?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Others lesions are ring enhancing and have mass effect while PML don't

30. HIV patient having fat deposition on back of neck and abdomen - like cushing
When cd4 count falls below 200. 2p in pcp =200
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
Aortic valve; endocardiits of AR p/w AV block and LBBB
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)

31. when we see echym gangrenosum?
<5000 copies/ml
AA gradient >35 or Po2 <70
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
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

32. How to give postexposure prophylaxis for HIV
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
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.
Others lesions are ring enhancing and have mass effect while PML don't
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ

33. pathophysiology of toxic shock syndrom?
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
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
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

34. low grade fever - maculopapular rash - lymphadenopathy
AA gradient >35 or Po2 <70
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

35. what if monospot test is neg in IM?
Do EBV antibody test
ELISA; initial visit - 6 - 12 and 24 weeks;
Oropharyngeal secretions; hence named as kissing disease
Voriconazol. mycetoma-surgical removal

36. pneumococcal vaccine indication?
High risk 19-64; 1-2 dose - above 65; one dose
If a sample is ELISA positive - it is tested fro western blot for confirmation
Postcoital voiding - increased intake of cranberry juice
<5000 copies/ml

37. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Upper lobes; any fibrosis in this area suggestive of latent TB
HBIG hep B immunoglobulin
Aortic valve; endocardiits of AR p/w AV block and LBBB
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

38. What is tx for herpes zoster
Acyclovir
Do EBV antibody test
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.

39. How to dx cryptococal meninggits
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Do EBV antibody test
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
Td every 10 years - tdap once before 65 and after 65

40. How to tx pseudomonas?
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
Upper lobes; any fibrosis in this area suggestive of latent TB
Others lesions are ring enhancing and have mass effect while PML don't
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -

41. foot infections in DM
Immune mediated; circulating IgG and IgM to penicillin derivatives
Pt who have been treated before for latent TB
If a sample is ELISA positive - it is tested fro western blot for confirmation
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

42. thrombocytopenia in HIV
Similar pathophysiology as ITP - tx zidovudine
Clostridium perfringens after penetrative injuries/wounds
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Immune mediated; circulating IgG and IgM to penicillin derivatives

43. What is the criteria for Spontaneous bact peritonitis
Pegylated interferon and lamivudine
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
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads

44. acute onset +rusty sputum
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol
Immune mediated; circulating IgG and IgM to penicillin derivatives
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -

45. antibiotic with good prostate penetration?
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
Voriconazol. mycetoma-surgical removal
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Massive (even 20L/day) fluid resuscitaiton which may clear toxin

46. How to differentiate gonococcal and nongonoccal urethritis?
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
Aortic valve; endocardiits of AR p/w AV block and LBBB
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

47. causative organisms of uti
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
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
Acyclovir

48. aspergillosis
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Pt who have been treated before for latent TB
Voriconazol. mycetoma-surgical removal

49. what would be viral load after 4 weeks
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
<5000 copies/ml
Td every 10 years - tdap once before 65 and after 65
Reddish orange discoloration of urine - feces - sweat - tears - sputum

50. which heart valve is closer to ventricular conduction system/
Pegylated interferon and lamivudine
Aortic valve; endocardiits of AR p/w AV block and LBBB
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
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