The correct answer is D, "sodium hypochlorite," as it is an effective sporicidal disinfectant for Clostridioides difficile that the infection preventionist (IP) should recommend. According to the Certification Board of Infection Control and Epidemiology (CBIC) guidelines, Clostridioides difficile (C. difficile) is a spore-forming bacterium responsible for significant healthcare-associated infections (HAIs), and its spores are highly resistant to many common disinfectants. Sodium hypochlorite (bleach) is recognized by the Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA) as a sporicidal agent capable of inactivating C. difficile spores when used at appropriate concentrations (e.g., 1:10 dilution of household bleach) and with the recommended contact time (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.4 - Implement environmental cleaning and disinfection protocols). This makes it a preferred choice for environmental disinfection in outbreak settings or areas with known C. difficile contamination.

Option A (quaternary ammonium compound) is effective against many bacteria and viruses but lacks sufficient sporicidal activity against C. difficile spores, rendering it inadequate for this purpose. Option B (phenolic) has broad-spectrum antimicrobial properties but is not reliably sporicidal and is less effective against C. difficile spores compared to sodium hypochlorite. Option C (isopropyl alcohol) is useful for disinfecting surfaces and killing some pathogens, but it is not sporicidal and evaporates quickly, making it ineffective against C. difficile spores.

The IP’s recommendation of sodium hypochlorite aligns with CBIC’s emphasis on selecting disinfectants based on their efficacy against specific pathogens and adherence to evidence-based guidelines (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.5 - Evaluate the environment for infection risks). Proper use, including correct dilution and contact time, is critical to ensure effectiveness, and the IP should collaborate with the Product Evaluation Committee to ensure implementation aligns with safety and regulatory standards (CDC Guidelines for Environmental Infection Control in Healthcare Facilities, 2019).