Environmental Persistence of High-Risk KPC-Producing ST463 Pseudomonas aeruginosa in Intensive Care Units in East China.

Purpose: This study aimed to investigate the distribution and characteristics of high-risk, difficult-to-treat resistant Pseudomonas aeruginosa (DTR-PA) sequence type (ST) 463 in intensive care units (ICUs) in East China. Patients and Methods: This 11-month study investigated Carbapenem-resistant Pseudomonas aeruginosa (CRPA) in patients and environments across four ICUs in a large teaching hospital in East China. It involved whole-genome sequencing, antibiotic susceptibility testing, and biofilm-forming ability testing of all the isolates. Molecular epidemiology and phylogenetic relationships were assessed using multi-locus sequence typing (MLST) and core genome multi-locus sequence typing (cgMLST). Bacterial virulence was evaluated using Galleria mellonella infection model. Results: A total of 54 CRPA were isolated from the environment and inpatients in ICUs and classified into 25 STs, with ST463 identified as the predominant ST (13/54, 24.07%). All 13 ST463 PA isolates belonged to DTR-PA, including 4 from patients and 9 from environments primarily from wastewater dumping pools. All ST463-DTR-PA isolates carried bla KPC-2 and exhibited exoU+/exoS+ virulence genotype. There were 3 KPC-ST463-DTR-PA additionally carried bla AFM-1, resulting in resistance to last-resort antibiotics. ST463-DTR-PA had higher biofilm-forming ability and mortality in infected larvae than non-ST463-DTR-PA. Both clinical and environmental strains showed high virulence. CgMLST results revealed that several ST463-DTR-PA isolated from different ICUs were genetically related. Conclusion: KPC-ST463-DTR-PA can widely colonize in ICU environment. Contamination and incomplete disinfection in humid environments may provide evolutionary opportunities for ST463-DTR-PA. Hence, it's worth our vigilance about the growing prevalence of ST463-DTR-PA in East China's ICUs. Meanwhile, it is important to strengthen the management of the ICU environment, especially water reservoirs, and even to promote the management of patients without water.