Comparison between IMP carbapenemase-producing Enterobacteriaceae and non-carbapenemase-producing Enterobacteriaceae: a multicentre prospective study of the clinical and molecular epidemiology of carbapenem-resistant Enterobacteriaceae

Background: Carbapenem-resistant Enterobacteriaceae (CRE) are classified as carbapenemase-producing Enterobacteriaceae (CPE) and non-CPE; the majority of CPE in Japan produce IMP carbapenemase. Objectives: We evaluated the clinico-epidemiological and microbiological information and effects of IMP-type carbapenemase production in CRE. Methods: Patients with isolations of CRE (MICs of meropenem >= 2mg/L, imipenem >= 2mg/L or cefmetazole >= 64mg/L) from August 2016 to March 2018 were included. Microbiological analyses and WGS were conducted and clinical parameters were compared between groups. Independent predictors for the isolation of CPE from patients were identified by logistic regression. For comparing clinical outcomes, a stabilized inverse probability weighting method was used to conduct propensity score-adjusted analysis. Results: Ninety isolates (27 CPE and 63 non-CPE) were collected from 88 patients (25 CPE and 63 non-CPE). All CPE tested positive for IMP carbapenemase. Antibiotic resistance (and the presence of resistance genes) was more frequent in the CPE group than in the non-CPE group. Independent predictors for CPE isolation were residence in a nursing home or long-term care facility, longer prior length of hospital stay (LOS), use of a urinary catheter and/or nasogastric tube, dependent functional status and exposure to carbapenem. Although in-hospital and 30 day mortality rates were similar between the two groups, LOS after CRE isolation was longer in the CPE group. Conclusions: IMP-CPE were associated with prolonged hospital stays and had different clinical and microbiological characteristics compared with non-CPE. Tailored approaches are necessary for the investigational and public health reporting, and clinical and infection prevention perspectives for IMP-CPE and non-CPE.