Addiction Medicine Certification Infection Control & Prevention 3 — Questions and Answers
Question 1: Which route of HIV transmission carries the HIGHEST per-act risk?
- Receptive anal intercourse
- Sharing injection equipment (Correct answer)
- Needle-stick injury in healthcare settings
- Receptive vaginal intercourse
Correct answer: Sharing injection equipment
Sharing injection equipment (particularly syringes) carries the highest per-act HIV transmission risk, estimated at approximately 63 per 10,000 exposures.
Question 2: Necrotizing fasciitis in a patient who injects drugs is most commonly caused by which type of organism?
- Single aerobic gram-negative rods only
- Polymicrobial infection with aerobic and anaerobic bacteria (Correct answer)
- Candida species alone
- MRSA exclusively
Correct answer: Polymicrobial infection with aerobic and anaerobic bacteria
Necrotizing fasciitis in people who inject drugs is typically polymicrobial, involving a mix of aerobic and anaerobic bacteria that produce synergistic tissue destruction.
Question 3: A patient with alcohol use disorder asks about infection risk. Which organism is most associated with spontaneous bacterial peritonitis (SBP) in cirrhotic patients?
- Staphylococcus aureus
- Escherichia coli (Correct answer)
- Clostridium difficile
- Mycobacterium tuberculosis
Correct answer: Escherichia coli
Escherichia coli and other gram-negative enteric bacteria, particularly E. coli, are the most common causative organisms of spontaneous bacterial peritonitis in cirrhotic patients.
Question 4: Which of the following best describes pre-exposure prophylaxis (PrEP) for HIV?
- A single-dose injection given after high-risk exposure within 72 hours
- Daily antiretroviral medication taken by HIV-negative individuals to prevent infection (Correct answer)
- A vaccine that prevents HIV acquisition
- Treatment given to HIV-positive individuals to reduce viral load
Correct answer: Daily antiretroviral medication taken by HIV-negative individuals to prevent infection
PrEP consists of daily antiretroviral medications (e.g., tenofovir/emtricitabine) taken by HIV-negative individuals to significantly reduce their risk of acquiring HIV.
Question 5: Which tuberculosis test is preferred for immunocompromised patients, including those with HIV, due to superior sensitivity?
- Tuberculin skin test (TST/PPD)
- Interferon-gamma release assay (IGRA) (Correct answer)
- Chest X-ray alone
- Sputum acid-fast bacilli smear
Correct answer: Interferon-gamma release assay (IGRA)
IGRAs (e.g., QuantiFERON-TB Gold) are preferred in immunocompromised individuals because they are less affected by anergy and do not require a return visit.
Question 6: Patients with severe alcohol use disorder are at increased risk for pneumonia caused by which atypical organism due to impaired mucociliary clearance and aspiration?
- Legionella pneumophila
- Klebsiella pneumoniae (Correct answer)
- Pneumocystis jirovecii
- Histoplasma capsulatum
Correct answer: Klebsiella pneumoniae
Klebsiella pneumoniae is classically associated with aspiration pneumonia in alcoholic patients, often producing the characteristic 'currant jelly' sputum.
Question 7: Which of the following statements about methicillin-resistant Staphylococcus aureus (MRSA) is correct in the context of injection drug use?
- MRSA is sensitive to beta-lactam antibiotics like oxacillin
- MRSA prevalence is low among people who inject drugs
- Vancomycin is a first-line treatment for serious MRSA infections (Correct answer)
- MRSA only causes skin infections and never causes bacteremia
Correct answer: Vancomycin is a first-line treatment for serious MRSA infections
Vancomycin remains the standard first-line treatment for serious MRSA infections, including bacteremia and endocarditis in people who inject drugs.
Addiction Medicine Certification Infection Control & Prevention 3
Which route of HIV transmission carries the HIGHEST per-act risk?