ST11 Carbapenem-Resistant Klebsiella pneumoniae Clone Harboring Capsular Type KL25 became the primarily prevalent capsular serotypes in a Tertiary Teaching Hospital in China.

Abstract

Objective: The spread of carbapenem-resistant Klebsiella pneumoniae (CRKP) that produces Klebsiella pneumoniae carbapenemase-2 (KPC-2) has garnered significant attention due to their increasing prevalence. In China, the dissemination of KPC-2-producing CRKP is predominantly linked to sequence type 11 (ST11), with the capsular serotypes KL47 and KL64 being the primary capsular identified.

Methods: Sixty-four CRKP-ST11 strains were collected from 2020 to 2023. We performed whole-genome sequencing on all isolated ST11-CRKP strains. Antibiotic susceptibilities were tested with VITEK 2 systems. Growth curve test and in vitro competition experiments were used to assess growth adaptability of different capsular type isolates. Moreover, the biofilm assessment and phagocytosis assay were performed to evaluate the virulence of the CRKP isolates.

Results: During the observed period, a no subclonal shift was perceived within the prevailing ST11-CRKP clone, wherein the previously dominant KL64 and KL47 serotypes have been largely supplanted by the KL25 serotype since 2022. The ST11-KL25-CRKP strain significantly outgrew both ST11-KL64-CRKP and ST11-KL47-CRKP. Additionally, ST11-KL25-CRKP displayed a greater enhanced capacity to form biofilms than ST11-KL64-CRKP and ST11-KL47-CRKP. Furthermore, the ST11-KL25-CRKP strain demonstrated enhanced resistance to phagocytosis than both of its counterparts.

Conclusion: ST11-KL25-CRKP possesses a remarkable level of adaptability and has the potential to regionally replace ST11-KL64-CRKP as the predominant strain in the region. And the novel and high-risk ST11-KL25-CRKP strain may indicate stronger virulence.