Active surveillance and molecular epidemiological study of intestinal colonization of carbapenem-resistant Enterobacterales / 中华传染病杂志

ABSTRACT

Objective:To investigate the detection rate of intestinal colonization of carbapenem-resistant Enterobacterales (CRE) in inpatients, and to analyze the molecular epidemiological characteristics of CRE strains.Methods:This was a prospective study. Stool, rectal swab or perianal swab specimens of 213 inpatients in the surgical intensive care unit (SICU), medical intensive care unit (MICU) and the department of hematology (transplantation ward) in The Second Hospital of Anhui Medical University were collected from March to December, 2019. MacConkey plate containing carbapenems was used to screen CRE strains, and bacteria identification and drug susceptibility test were conducted. Key strains were selected for whole genome sequencing (WGS). Besides, multilocus sequence typing, capsular serotype, drug resistance gene, virulence gene and plasmid carrying characteristics of these strains were analyzed. Using KPN FJ723042 sequence as a reference, the single-nucleotide polymorphism (SNP) of all strains was analyzed.Results:Twenty-three CRE strains were detected, with a detection rate of 10.8%(23/213), which included 15(65.2%) carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates, three (13.0%) Escherichia coli strains, three (13.0%) Enterobacter cloacae strains and two (8.7%) Citrobacter freundii strains. SNP cluster analysis showed that the 15 CRKP strains had two main clonotypes, which were both predominant in SICU. Fifteen strains of CRKP were type ST11-K64. All these strains carried β-lactamase Klebsiella pneumoniae carbapenemase 2 ( blaKPC-2 ), and 12 strains carried regulator of mucoid phenotype gene A2 ( rmpA2) and iucABCD. Conclusions:The detection rate of intestinal colonization of CRE in inpatients is high, and most strains are CRKP of type ST11-K64. These CRKP strains have both multidrug resistance and virulence characteristics, which are risks for hospital transmission.