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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. when we see echym gangrenosum?
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
Antipseudomonal penicillin (pipercillin) or cephalosporin (ceftazdidime/cefepime) and aminoglycoside (tobramycin/amikacin)
ELISA; initial visit - 6 - 12 and 24 weeks;
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

2. what if monospot test is neg in IM?
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Postcoital voiding - increased intake of cranberry juice
Do EBV antibody test

3. What is difference between uti relapse versus recurrence?
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
ELISA; initial visit - 6 - 12 and 24 weeks;
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
Mainly clinical - epidemiological and seasonal setting

4. INH
Hepatotoxitcity incidence 2.6% - commonly seen in alcoholic - liver disease - >50
Viral load and CD4 count
Pt who have been treated before for latent TB
Aortic valve; endocardiits of AR p/w AV block and LBBB

5. damae that is about to occur?
HIV viral load
Acyclovir
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
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.

6. clinical manifestation of mucomycosis
Either TB or aspergillosis
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
Rifampin600mg q12. or cipro
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

7. what would be viral load after 4 weeks
Reddish orange discoloration of urine - feces - sweat - tears - sputum
<5000 copies/ml
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV

8. foot infections in DM
AA gradient >35 or Po2 <70
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
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
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer

9. What is the Tx of cryptococcal meninngitis
If a sample is ELISA positive - it is tested fro western blot for confirmation
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.
Acyclovir

10. oligodendrocyte with intranuclear inclusion and demyelination in HIV patient
PML; focal neurological deficit like MM; no specific tx; regress with HAART
HIV present in very minimal quantities in human saliva. exposure/contact of saliva will never trasmit HIV
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

11. low grade fever - maculopapular rash - lymphadenopathy
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Quinoloes (cipro/levo) cure rate 70% - TMP-SMZ
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

12. How to tx pcp?
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
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)

13. patient with diagnosed case of cryptococcal meningitis p/w severe headache and vomiting
ELISA and western blot of synovial fluid.
When cd4 count falls below 200. 2p in pcp =200
Need lumbar puncture to relieve pressure; they have high opening pressure >350
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region

14. What is tx for herpes zoster
Within 6 months viral load will be <50
Acyclovir
Rifampin600mg q12. or cipro
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

15. INH
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Every 3-4 hours to determine appropritate time to start HAART
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

16. When to tx asymptomatic bacteriurea >100 -000?
Pregnacy - urologic procedure - hip arthoplastu
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)
Within 6 months viral load will be <50

17. What is the criteria for Spontaneous bact peritonitis
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
Oropharyngeal secretions; hence named as kissing disease
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

18. infiltrate in upper lobe of lung?
Others lesions are ring enhancing and have mass effect while PML don't
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
Either TB or aspergillosis
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.

19. What are the behavioral interventions decrease the risk of UTI
Postcoital voiding - increased intake of cranberry juice
<5000 copies/ml
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin

20. rifampin
S. pneumonie. differentitate this from atypical pneumonia and pcp which are gradual onset - non productive cough -
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Reddish orange discoloration of urine - feces - sweat - tears - sputum
Non pregnant premanopausal - elderly - dm - sci - chronic foley

21. How to tx TSS?
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
Monospot test which screen heteropile ab that agglutinate horse rbc
Voriconazol. mycetoma-surgical removal
Pt who have been treated before for latent TB

22. What is the prognosis of lyme arthritis?
PML; focal neurological deficit like MM; no specific tx; regress with HAART
Monospot test which screen heteropile ab that agglutinate horse rbc
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

23. pathophysiology of toxic shock syndrom?
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
Pt who have been treated before for latent TB
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain

24. 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.
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved
Voriconazol. mycetoma-surgical removal
N meningitidis colonize in nasopharynx; cause mucosal invasion - systemic bacterimia and seeding in the meninges

25. How to confirm chlamydia infection?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Chlamydia pcr - 88% sensitivity and 99% specificity; if negative think about MUT organims; mycoplasma - ureaplasma and trichomonas; tx MUT with metronidazole
Bronchoalveolar washing and transbronchial biopsy
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle

26. how im is transmitted?
6-12 weeks
Trimethoprime-sulphamethoxazole if intolerant give pentamidine (cause pancreatitis p for p)
Oropharyngeal secretions; hence named as kissing disease
Within 6 months viral load will be <50

27. When to give prophylaxis against MAC
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Aortic valve; endocardiits of AR p/w AV block and LBBB
For mac - we give azithromycin - mac has a for azithromycin; cd4 <50; remember CML designates for <50 c-cmv; m- mac - L-cns lymphoma
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

28. gas gangrene
6-12 weeks
Aortic valve; endocardiits of AR p/w AV block and LBBB
HIV viral load
Clostridium perfringens after penetrative injuries/wounds

29. pneumococcal vaccine indication?
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.
HIV viral load
250 neutrophil/mm3 in peritoneal fluid - tx empiric abx; if tremor or other neuro sign give lactulose

30. which heart valve is closer to ventricular conduction system/
ELISA and western blot of synovial fluid.
Blastomycosis
Petechial rash developed 3-5th days of illness begins ankle or wrist and spread to palm/soles
Aortic valve; endocardiits of AR p/w AV block and LBBB

31. How to dx progressive multifocal leukoencephalopathy
Throat cx of positive of GAS means bacteria are colonized bur not infected in IM. tx with ampi can trigger maculopaular rash
Immunocompromised patient ? dec vision - weakness/tingling of extremities or other neurological symptoms - MRI nonenhancing lesion in parietooccipital region
Harrt ---rapid improvement of immune function---increased inflammatory reaction--worsening of clinical symptoms; self limiting....needs no tx
Voriconazol. mycetoma-surgical removal

32. thrombocytopenia in HIV
Pregnacy - urologic procedure - hip arthoplastu
If a sample is ELISA positive - it is tested fro western blot for confirmation
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
Similar pathophysiology as ITP - tx zidovudine

33. How to dx lyme arthritis?
Pregnacy - urologic procedure - hip arthoplastu
Start with amphotericin B and flucytosin for 2 weeks - if there is clinical improvement discontinue them and start with fluconazol
ELISA and western blot of synovial fluid.
Pegylated interferon and lamivudine

34. can HIV transmitted through human bite?
HIV syndrome or anti-retroviral syndrome; 2-3w after virus exposure. similar to IM.
Mainly clinical - epidemiological and seasonal setting
Every 3-4 hours to determine appropritate time to start HAART
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 - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Within 72hrs of unprotected sex with HIV pos person - give two nucleosidase inhibitors (eg. zidovudin - lamivudein - tenofovir -) X4w
Tampoon in nostril/vagina. think t for t - staph release exotoxin --activation of t cells directly--release of massive cytokines.
Immune mediated; circulating IgG and IgM to penicillin derivatives

36. HIV patient having fat deposition on back of neck and abdomen - like cushing
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
Staph - GBS - proteus - pseudomona - e coli - candida - bacteroids; organisms isolated only from deep curettage of ulcer
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Most common E coli; less common; klebsiella - enterobacter - proteus - staph - groupd d strep

37. dame that has already occurred
Cd4 count
Non pregnant premanopausal - elderly - dm - sci - chronic foley
Either TB or aspergillosis
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx

38. where TB normally affects
Upper lobes; any fibrosis in this area suggestive of latent TB
Massive (even 20L/day) fluid resuscitaiton which may clear toxin
ELISA and western blot of synovial fluid.
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

39. How to differentiat PML from toxoxplasmosis - cns lymphoma adn brain abscess

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40. after exposure of HIV when antibody testing is performed?
At first 4 weeks - then 8-12weks; remeasusing every 2m until viral load is undetectatable. then every 3 months
Pt who have been treated before for latent TB
ELISA; initial visit - 6 - 12 and 24 weeks;
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

41. hypertriglyceridemia in HIV
6-12 weeks
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
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
Exacerbate by HAART; give statin - if triglyceride >500 - give a fibrate

42. after bone marrow transplant - patient develop headache - fever - cought and chest pain. What is dx?
Aspergillosis. common in bone marrow transplants. typically involves lungs and sinuses
4 months; characterized by knee joint effusion-large amount - joint stiffness - pain
Non pregnant premanopausal - elderly - dm - sci - chronic foley
2 weeks in neutropenic patients and 7-10 days after catheter removed/patient improved

43. when HIV patient develop pcp?
ELISA; initial visit - 6 - 12 and 24 weeks;
AMS - focal neurological signs - seizures - multiorgan dysfunction - death; tx; doxycycline; for pregnant give chloramphenicle
When cd4 count falls below 200. 2p in pcp =200
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

44. how CMV presents in immunocompromised patients
Pregnacy - urologic procedure - hip arthoplastu
Fever of unknown orign - esophagiti - retinitis - diarrhoea - encephalits
HIV lipodystrophy; no correlation with viral load; p/w insulin resistance and dyslipidemia (inc cholesterol - dec HDL)
Give nystatin suspension or clotrimazol with an oral antifungal eg. fluconazol

45. How to give postexposure prophylaxis to patient who received vaccine but titer inadequate
Voriconazol. mycetoma-surgical removal
HBIG hep B immunoglobulin
Leukocytosis >100 cells - dec glucose - inc protien - inc opening pressure; in viral there will be lymphocytosis - normal glucose (virus doesn't eat) -
Classic triad: fever - pharyngitis - postauricular lymaphdenopahty - caused by EBV

46. What is the Tx of STD uretheritis?
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
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
ELISA; initial visit - 6 - 12 and 24 weeks;

47. What is the classic signs of nec fasc?
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
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
Only vaccine. immunoglobuin not required. previously unvaccinated person will receive both.
Vitamin B6 antagonist - can cause peripheral neuropathy if not give with b6

48. How to dx IM?
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
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
Monospot test which screen heteropile ab that agglutinate horse rbc

49. How often HIV postiive patients CD4 count needs to be evaluated?
Rifampin600mg q12. or cipro
HIV viral load
Every 3-4 hours to determine appropritate time to start 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

50. reddish colored papules with central umbilication in HIV or immunocompromised patient
Voriconazol. mycetoma-surgical removal
Fever - facial swelling - nasal discha - maxilary pain and tenderness - headache - present in DKA - caused by zygomycetes tx surgical debridement and intranasal amphotericin
Tx with amoxicillin or ceftriaxone. 90% are disease free after one year after tx
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