Increased Mortality Among Carbapenemase-Producing Carbapenem-Resistant Enterobacteriaceae Carriers Who Developed Clinical Isolates of Another Genotype

Background. Carbapenemase production by carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) is encoded by a variety of genes on mobile genetic elements. Patients colonized by 1 genotype of CP-CRE may be subsequently infected by another genotype of CP-CRE. We sought to determine whether CP-CRE carriers who developed infection with another genotype had a higher mortality risk. Methods. A retrospective cohort study was conducted using collected data from January 2012 to December 2016. Clinical isolates of CP-CRE were analyzed among the CP-CRE carriers who had developed an infection during their stay in the hospital. Comparison was made between CP-CRE carriers who developed clinical isolates of another genotype and those whose clinical isolates were of the same CP-CRE genotype that they were originally colonized with. The primary outcome analyzed was the 14-day mortality rate. Results. A total of 73 CP-CRE carriers who had developed infection were analyzed. Ten (15.4%) of the carriers who developed an infection with clinical isolates of the same CP-CRE genotype died within 14 days, whereas 5 (62.5%) of those who developed an infection with clinical isolates of a different genotype died. This represented a 6-fold increase (adjusted relative risk, 6.36; 95% confidence interval, 1.75-23.06; P = .005) in the 14-day mortality rate. Conclusions. CP-CRE carriers who developed clinical isolates of another genotype are at risk of increased mortality. This is a novel finding that is of interest to health care organizations worldwide, with profound implications for infection control measures, such as patient and staff cohorting.