Infection Control & Prevention Flashcards

A nurse removes gloves after caring for a patient on contact precautions, then immediately sanitizes hands with an alcohol-based hand rub. Thirty seconds later, she touches a clean medication cart. Which statement best describes the infection control risk in this scenario?

Answer: There is potential risk if the patient had Clostridioides difficile, as alcohol-based hand rub is ineffective against its spores.

Clostridioides difficile produces spores that are resistant to alcohol-based hand rubs. The WHO and CDC guidelines specifically recommend soap-and-water handwashing — not ABHR — after caring for patients with C. difficile. Even correct ABHR technique does not eliminate C. diff spores, posing a genuine transmission risk to the medication cart.

During a surgical procedure, the scrub technician's sterile gown sleeve briefly contacts the non-sterile back table drape edge. The circulating nurse is unavailable. What is the MOST appropriate immediate action?

Answer: Notify the surgeon and request a sterile gown change before continuing the procedure.

Any contact between a sterile field component and a non-sterile surface constitutes a break in sterile technique, regardless of duration. The scrub technician's gown sleeve must be considered contaminated. The correct action is to notify the surgeon and change the gown before continuing, as there is no acceptable method to re-sterilize a gown intraoperatively using bedside measures.

A patient with active pulmonary tuberculosis is being managed in a negative-pressure isolation room. The HVAC system temporarily fails, equalizing room pressure with the corridor for approximately 4 minutes before being corrected. What is the PRIORITY action for infection control personnel?

Answer: Document the pressure failure, conduct contact tracing for all corridor personnel present during the event, and notify the infection control department.

A negative-pressure room failure during TB isolation is a reportable infection control incident. The room may have allowed aerosolized M. tuberculosis droplet nuclei to migrate into the corridor. The priority is documentation of the event, identification of all individuals in the corridor during the breach period (contact tracing), and formal notification of the infection control team for exposure assessment — which may include TB testing follow-up for exposed personnel.

A healthcare worker sustains a needlestick injury from a needle used on an HIV-positive patient with a known undetectable viral load (< 20 copies/mL) on antiretroviral therapy. Regarding post-exposure prophylaxis (PEP), which statement is MOST accurate?

Answer: PEP should be initiated within 72 hours, as current evidence cannot guarantee zero transmission risk even with undetectable viral load.

While Undetectable = Untransmittable (U=U) is established for sexual transmission, occupational needlestick exposure guidelines still recommend initiating PEP within 72 hours regardless of source viral load, because compartmental differences in viral load (e.g., blood vs. tissue), assay variability, and the mechanics of percutaneous inoculation mean that risk cannot be categorically excluded. Delaying PEP beyond 72 hours renders it ineffective.

A central venous catheter (CVC) inserted 6 days ago is found to have purulent discharge at the insertion site. Blood cultures are drawn peripherally and through the catheter lumen. The peripheral culture grows Candida parapsilosis; the catheter-lumen culture is negative at 48 hours. How should this differential time-to-positivity (DTP) result be interpreted?

Answer: Because Candida parapsilosis has a high biofilm-forming capacity and catheter cultures can be falsely negative due to the biofilm matrix, CRBSI remains strongly suspected and catheter removal is indicated.

Candida parapsilosis is notorious for forming robust biofilms on catheter surfaces. Biofilm-embedded organisms shed intermittently, making intraluminal sampling frequently falsely negative despite active CRBSI. Furthermore, guidewire exchange is contraindicated in suspected fungal CRBSI. Current IDSA guidelines recommend catheter removal (not exchange) for candidemia with a CVC in situ, as antifungals cannot adequately eradicate biofilm. A negative lumen culture does not exclude CRBSI when purulence is present at the site.

In a hospital experiencing an outbreak of carbapenem-resistant Klebsiella pneumoniae (CRKP), contact tracing reveals that a colonized patient was bathed by two different nursing assistants using a shared bath basin. Which mechanism of transmission is MOST likely responsible for inter-patient spread in this scenario?

Answer: Common vehicle transmission via the contaminated bath basin acting as a fomite bridge between patients.

Bath basins are a well-documented fomite in hospital outbreaks of gram-negative pathogens including CRKP. The basin itself becomes colonized and, when shared between patients or between care episodes without adequate disinfection, acts as a common vehicle — directly inoculating a new host via the healthcare worker's hands or direct basin contact. This is classified as common vehicle (fomite-mediated contact) transmission, not airborne or droplet, as CRKP does not aerosolize meaningfully during bathing.