Unveiling the clonal dynamics and transmission mechanism of carbapenem-resistant Klebsiella pneumoniae in the ICU environment.

CRKP infections are a significant public health threat due to their high mortality and limited treatment options. This study aimed to investigate CRKP colonization and clonal dissemination mechanism in an ICU. From August 2019 to December 2019, 8668 samples were collected from patients and the ICU environment for CRKP screening. Positive samples underwent antimicrobial susceptibility testing, whole-genome sequencing, and molecular epidemiological analysis. Disinfectant sensitivity and ultraviolet (UV) resistance experiments were conducted to evaluate clonal persistence. The overall CRKP positive rate was 4.85% (420/8668), with higher rates in patients (14.77%, 247/1672) compared to environmental surfaces (2.47%, 173/6996). Intestinal and ventilator-related surfaces were identified as high-risk colonization sites. Molecular analysis revealed six sequence types, with ST11-KL64 (44.05%, 185/420) and ST15-KL112 (24.05%, 101/420) as dominant clones, both exhibiting elevated virulence. Notably, the emerging ST15-KL112 clone demonstrated enhanced resistance to disinfectants including chlorhexidine (MIC 8 mg/L) and benzalkonium chloride (32 mg/L). While most isolates produced KPC-2 (72.86%), OXA-232 prevalence (25.23%) exceeded prior reports. Crucially, ST11 strains survived standard UV disinfection (60-second exposure) at rates 1.3- to 5-fold higher than other clones (p < 0.01). Our findings highlight the critical role of disinfectant resistance in sustaining CRKP transmission. To mitigate outbreaks, we advocate for disinfectant rotation protocols targeting disinfectant-resistant clones and prolonged UV exposure times in ICUs. The persistence of resistant CRKP clones in the ICU environment, particularly their high tolerance to disinfectants, highlights the urgent need for enhanced infection control strategies, including tailored disinfection protocols and surveillance programs.