Short-Lived Success: Carbapenem-Resistant Enterobacterales Recolonization in Sinks Following Repeated Peroxide-Peracetic Acid-Based Foam Disinfection

Sink-drains/traps in healthcare facilities are recognized reservoirs of drug-resistant Gram-negative bacilli, yet effective remediation strategies remain uncertain. Using culture-based and metagenomic approaches, we evaluated the impact of a peroxide peracetic-acid(PPAA)-foam disinfectant applied at 3-, 5- or 7-day intervals over four-weeks in a controlled Sinklab and a hospital setting. Across all application frequencies and repeated applications, PPAA-foam was ineffective in reducing carbapenemase-producing Enterobacterales counts from baseline over 28days. Instead, treatment induced pronounced microbiome dysbiosis in sink-drains and traps, characterized by reduced community diversity, enrichment of Enterobacterales, and amplification of resistance determinants, including blaKPC and blaNDM. Hospital sinks exhibited comparable transient effects following PPAA-foam treatment, with rapid post-treatment recovery of both microbial communities and resistome. Together, these findings demonstrate that repeated chemical disinfection in established plumbing systems may destabilize drain microbiomes and paradoxically reinforce the persistence of high-risk pathogens and antimicrobial resistance, underscoring the need for ecologically informed alternatives to chemical-only interventions.