Correlation Between Carbapenemase-Producing Enterobacterales Load, Environmental Contamination, and Transmission in Critical Care Units

Carbapenemase-producing Enterobacterales (CPE) are multidrug-resistant bacteria that can colonize the gastrointestinal tract of hospitalized patients and spread within intensive care units (ICUs). Some colonized individuals may carry a particularly high bacterial burden and contribute disproportionately to environmental contamination and transmission to other patients. Identifying these high-risk individuals could improve infection prevention and control strategies. This prospective observational study will be conducted in the Adult Intensive Care Unit of Hospital Italiano de Buenos Aires. Patients identified as colonized with CPE through routine surveillance will undergo quantitative culture and real-time polymerase chain reaction (PCR) testing of rectal swabs to measure bacterial load. Environmental samples will also be collected from high-touch surfaces surrounding colonized patients. In selected cases, molecular typing methods will be used to evaluate genetic relatedness between patient and environmental isolates and to investigate possible transmission events. The primary objective is to determine the correlation between bacterial load measured by culture and the PCR cycle threshold (Ct) value. Secondary objectives include evaluating the association between bacterial load and environmental contamination, and assessing whether patients with higher bacterial loads are more likely to contribute to transmission within the ICU. Results may help identify patients with increased dissemination potential and support targeted infection prevention interventions.