Multicenter survey for carbapenemase-producing Enterobacterales in central Japan

Carbapenemase-producing Enterobacterales (CPE) raise concerns about the treatment options for infectious diseases and infection control. We conducted a multicenter study to clarify the molecular epidemiology of CPE in the Aichi Prefecture during the first 3-month period from 2015 to 2019. Carbapenemase production was screened using a modified carbapenem inactivation method, and the genotypes of the carbapenemase genes were determined by polymerase chain reaction sequencing. Genetic relatedness was analyzed using multilocus sequence typing (MLST). Twenty-four hospitals participated in this study. Of the 56,494 Enterobacterales strains detected during the study period, 341 (0.6%) that met the susceptibility criteria were analyzed. Sixty-five of the 341 strains were determined to be CPE, with an incidence rate of 0.12% (65/56,494). The bacterial species responsible for CPE were Klebsiella pneumoniae (n = 24), Enterobacter cloacae complex (n = 23), Klebsiella oxytoca (n = 10), and Escherichia coli (n = 8). Most of the carbapenemase genotypes were IMP-1 (58/65), and only three were IMP-6 types. Three E. coli strains that produced NDM-5 were detected. MLST analysis showed that Sequence type (ST) 78 was predominant in E. cloacae complex CPE (14/23, 60.9%). Meanwhile, various STs were detected in carbapenemaseproducing (CP) K. pneumoniae, of which ST37 and ST517 were the most common. The incidence rate of CPE in this region was comparable to national data. This 3-month surveillance revealed the spread of ST78 of CP E. cloacae complex and ST517 and ST592 of CP K. pneumoniae across hospitals, indicating the need to strengthen regional infection control programs.