Epidemiological Characteristics of Carbapenem-Resistant Enterobacterales in Japan: A Nationwide Analysis of Data from a Clinical Laboratory Center (2016-2022).

In Japan, nationwide epidemiological surveys on carbapenem-resistant Enterobacterales (CREs), including comprehensive information, are scarce, with most data available only through public reports. This study analyzed data on the Enterobacterales family collected from nationwide testing centers between January 2016 and December 2022, focusing on isolates that met the criteria for CRE in Japan based on drug susceptibility. We investigated 5,323,875 Enterobacterales isolates of 12 different species; among 4696 (0.09%) CRE strains, the proportion of major CRE isolates was as follows: Escherichia coli, 31.3%; Klebsiella pneumoniae, 28.0%; Enterobacter cloacae, 18.5%; and Klebsiella aerogenes, 6.7%. Moreover, over a 7-year period, Providencia rettgeri, E. cloacae, K. aerogenes, and K. pneumoniae demonstrated relatively high CRE percentages of 0.6% (156/26,185), 0.47% (869/184,221), 0.28% (313/110,371), and 0.17% (1314/780,958), respectively. The number of CRE strains isolated from different samples was as follows: urine, 2390; respiratory specimens, 1254; stool, 425; blood, 252; others, 375. In the broader context, including colonization, the predominant isolates of CREs collected at nationwide testing centers are E. coli and K. pneumoniae. Furthermore, recently, attention has been directed toward less common CRE species, such as Klebsiella oxytoca and Providencia rettgeri, and thus, it might be necessary to continue monitoring these less common species.