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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. When to give prophylaxis against MAC
Viral load and CD4 count
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Monospot test which screen heteropile ab that agglutinate horse rbc
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w

2. what would be viral load after 2-4m of HAART?
<500 copies/ml
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Blastomycosis
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

3. wisconsin - missisipi - ohio
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
If a sample is ELISA positive - it is tested fro western blot for confirmation
Blastomycosis
Aortic valve; endocardiits of AR p/w AV block and LBBB

4. How to tx IM?
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
Either TB or aspergillosis
Bed rest - NSAID - avoid contact sports; if patient develop SOB due to pharyngeal edema - give corticosteroid
PML; focal neurological deficit like MM; no specific tx; regress with HAART

5. when western blot is done for HIV testing
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Doesn't exceed more than 15 mm and size significantly decreases after 15 years
If a sample is ELISA positive - it is tested fro western blot for confirmation
Td every 10 years - tdap once before 65 and after 65

6. What is the pathophysiology of Meningococcal meningitis?
<500 copies/ml
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Viral load and CD4 count
Pt who have been treated before for latent TB

7. What is tx for herpes zoster
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Acyclovir
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

8. How to give postexposure prophylaxis for HIV
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
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
Mainly clinical - epidemiological and seasonal setting

9. What is tetanus - diptheria - pertusis recommendation?
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Td every 10 years - tdap once before 65 and after 65
Similar pathophysiology as ITP - tx zidovudine
AA gradient >35 or Po2 <70

10. How to dx cryptococal meninggits
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Ampicillin-sublactam; most bites contain eikenella

11. systolic HTN in elderly
Others lesions are ring enhancing and have mass effect while PML don't
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil

12. Tx of choice for human bites
Upper lobes; any fibrosis in this area suggestive of latent TB
Ampicillin-sublactam; most bites contain eikenella
HIV viral load
Aortic valve; endocardiits of AR p/w AV block and LBBB

13. What is characteristic for dx of rocky mountain spotted fever?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Ampicillin-sublactam; most bites contain eikenella
<500 copies/ml
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

14. INH
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
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
6-12 weeks

15. thrombocytopenia in HIV
Similar pathophysiology as ITP - tx zidovudine
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Clostridium perfringens after penetrative injuries/wounds

16. What is the Tx of STD uretheritis?
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
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
Oropharyngeal secretions; hence named as kissing disease

17. How often viral load is monitored after HAART?
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
Postcoital voiding - increased intake of cranberry juice
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months

18. How to tx pcp?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Need lumbar puncture to relieve pressure; they have high opening pressure >350
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

19. how im is transmitted?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Oropharyngeal secretions; hence named as kissing disease
Blastomycosis
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

20. When to tx asymptomatic bacteriurea >100 -000?
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
HIV viral load
Pregnacy - urologic procedure - hip arthoplastu
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses

21. What is difference between uti relapse versus recurrence?
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Upper lobes; any fibrosis in this area suggestive of latent TB
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
Doesn't exceed more than 15 mm and size significantly decreases after 15 years

22. How to differentiate gonococcal and nongonoccal urethritis?
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Aortic valve; endocardiits of AR p/w AV block and LBBB
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
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

23. rifampin
Pregnacy - urologic procedure - hip arthoplastu
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
Clostridium perfringens after penetrative injuries/wounds

24. What are the subjective /objective measure of encephalopathy?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Do EBV antibody test
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

25. How to dx?
6-12 weeks
Mainly clinical - epidemiological and seasonal setting
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

26. causative organisms of uti
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Pt who have been treated before for latent TB
HIV viral load

27. 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)
Monospot test which screen heteropile ab that agglutinate horse rbc
<5000 copies/ml
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

28. dame that has already occurred
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine
Td every 10 years - tdap once before 65 and after 65
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
Cd4 count

29. reddish colored papules with central umbilication in HIV or immunocompromised patient
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
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

30. How to dx bacterial meningitis from CSF study?

31. how CMV presents in immunocompromised patients
ELISA; initial visit - 6 - 12 and 24 weeks;
6-12 weeks
AA gradient >35 or Po2 <70
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits

32. damae that is about to occur?
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
AA gradient >35 or Po2 <70
Blastomycosis
HIV viral load

33. INH
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
HBIG hep B immunoglobulin
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles

34. clinical manifestation of mucomycosis
HBIG hep B immunoglobulin
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
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
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

35. What is the mch of ampicillin induced rash in IM
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Immune mediated; circulating IgG and IgM to penicillin derivatives
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

36. drugs work well on hypertriglyceridia?
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
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Gemfibrozil and other fibrate drugs; statin and niacin also work not as good as fibrate drugs like gemfibrozil
Others lesions are ring enhancing and have mass effect while PML don't

37. acute febrile reaction develops after starting penicilin tx to syphilis patient
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
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
Vaccine titer >10mU/ml

38. How often HIV postiive patients CD4 count needs to be evaluated?
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Every 3-4 hours to determine appropritate time to start HAART
Due to decrease elasticity of arterial wall; only systolic - diastolic normal - wide pulse pressure
Markedly elevated csf pressure >200 - inc protein - low glucose ; tx amphotericin and flucytosine

39. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Need lumbar puncture to relieve pressure; they have high opening pressure >350
ELISA and western blot of synovial fluid.
Cd4 count

40. What is used for prophylaxis against meningo..meningitis?
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Rifampin600mg q12. or cipro
Vaccine titer >10mU/ml

41. after exposure of HIV when antibody testing is performed?
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Pegylated interferon and lamivudine
ELISA; initial visit - 6 - 12 and 24 weeks;
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.

42. What are indicators for progression of HIV
Viral load and CD4 count
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.
Bronchoalveolar washing and transbronchial biopsy
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

43. How long abx is given in pseudomonas infection?
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
Oropharyngeal secretions; hence named as kissing disease
Td every 10 years - tdap once before 65 and after 65
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

44. hypertension in children
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
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
Immune mediated; circulating IgG and IgM to penicillin derivatives
Pregnacy - urologic procedure - hip arthoplastu

45. What is the criteria for Spontaneous bact peritonitis
Most common; fibromuscular dysplasia - Rt renal artery more common - angiography string of beads
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
Mainly clinical - epidemiological and seasonal setting
Postcoital voiding - increased intake of cranberry juice

46. How to dx adequate response to HBV vaccine
<5000 copies/ml
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Vaccine titer >10mU/ml
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

47. What is the classic signs of nec fasc?
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
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
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
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

48. When to tx influenza with antiviral therapy?
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
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
ELISA; initial visit - 6 - 12 and 24 weeks;
PML; focal neurological deficit like MM; no specific tx; regress with HAART

49. when not to give INH therapy if ppd positive and patient asyptomatic
CTP subjective; MELD objective; meld uses serum billirubin - inr and serum creatinin. meld used to determine 90 day mortality of liver diease
Jarish-Herxheimer reaction; immunologica reaction due to rupture of sprochetes
If a sample is ELISA positive - it is tested fro western blot for confirmation
Pt who have been treated before for latent TB

50. gas gangrene
Clostridium perfringens after penetrative injuries/wounds
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose
HBIG hep B immunoglobulin
Pt who have been treated before for latent TB