Study on the correlation between Carbapenem-Resistant Klebsiella pneumoniae infection strains and intestinal colonization strains in Intensive Care Unit of a tertiary hospital in China.

Abstract

Objectives: Colonization by Carbapenem-Resistant Klebsiella pneumoniae (CRKP) is associated with the risk of developing CRKP infection. Whether infected strains come from colonized strains is not well known.

Methods: An observational, prospective cohort study (July 2022 to June 2023) was conducted on ICU patients undergoing rectal CRKP colonization screening. Antibiotic susceptibility testing, modified carbapenem inactivation method (mCIM), serum bactericidal and phagocytic assays, and whole genome sequencing (WGS) were performed on intestinal colonization and infection site isolates from 7 ICU patients.

Results: Among 412 ICU patients included, 88 were screened positive. Out of 82 patients who experienced colonization during hospitalization, 41 (50.0%) developed infections. 14 CRKP strains isolated from 7 patients were positive for carbapenemase in mCIM and exhibited similar resistance and virulence phenotype. WGS showed that the 14 CRKP, including 2 ST11, 2 ST15, and 10 ST5422, were bla_KPC-2 producing strains, and the genetic environment surrounding bla_KPC-2 was the same. Comparing the colonized and infected strains of the same patient, they both carried identical virulence genes, but the resistance genes and plasmids were not completely the same, however, the SNPs differed by less than 10.

Conclusions: Nosocomial CRKP infection should focus on preventing intestinal colonization in hospitalized patients. Small SNPs differences indicated that the infected strain may have originated from the colonized strain, but some resistance genes or plasmids may have been obtained during this transformation process. bla_KPC-2-carrying K. pneumoniae ST5422 was first reported in our study, and its genetic relationship was closely related to the clone strain ST11.