Molecular Epidemiology of Carbapenem-Resistant in the United States, 2013-2017.

Healthcare-associated carbapenem-resistant (CRAB) infections are a serious threat associated with global epidemic clones and a variety of carbapenemase gene classes. In this study, we describe the molecular epidemiology, including whole-genome sequencing analysis and antimicrobial susceptibility profiles of 92 selected, nonredundant CRAB collected through public health efforts in the United States from 2013 to 2017. Among the 92 isolates, the Oxford (OX) multilocus sequence typing scheme identified 30 sequence types (STs); the majority of isolates ( = 59, 64%) represented STs belonging to the international clonal complex 92 (CC92). Among these, ST208 ( = 21) and ST281 ( = 20) were the most common. All isolates carried an OXA-type carbapenemase gene, comprising 20 alleles. Ninety isolates (98%) encoded an intrinsic OXA-51-like enzyme; 67 (73%) harbored an additional acquired gene, most commonly ( = 45; 49%). Compared with isolates harboring only intrinsic oxacillinase genes, acquired gene presence was associated with higher prevalence of resistance and a higher median minimum inhibitory concentration to the carbapenem imipenem (64 μg/mL vs. 8 μg/mL), and antibiotics from other drug classes, including penicillin, aminoglycosides, cephalosporins, and polymyxins. These data illustrate the wide distribution of CC92 and high prevalence of acquired carbapenemase genes among CRAB in the United States.