Veterans Health Administration monitoring of carbapenem-resistant Enterobacteriaceae (CRE) trends from 2006 to 2015 shows a rise in resistance rates of E. cloacae complex nationwide.

The first major CRE outbreak, Klebsiella pneumoniae, occurred in the eastern United States in the early 2000s and has since spread across the country. K. pneumoniae has recently shown a decrease in resistance rates in the region including New York, both in the current VHA-based study and in a 2016 study of three New York City hospitals.

“CRE trends during 2006-2015 in the VHA recapitulate the epidemic of carbapenem-resistant K. pneumoniae in the United States and indicate that a ‘second epidemic’ of carbapenem-resistant E. cloacae complex appears to be unfolding,” wrote Brigid M. Wilson, PhD, of Louis Stokes Cleveland Department of Veterans Affairs Medical Center, and her coauthors.

The researchers used VHA network data to identify 128,431 K. pneumoniae and 38,219 E. cloacae complex (which refers to the species E. cloacae, E. asburiae, E. kobei, E. hormaechei, and E. xiafangensis) isolates from patients hospitalized in 140 facilities in 40 states, the District of Columbia, and Puerto Rico from 2006 to 2015. These isolates, paired with their carbapenem susceptibility test results, show the rise and geographic concentration of the CRE cases over the decade.

The increased E. cloacae complex resistance in 2014-2015 was centered around the Pacific Coast and Southwest regions. The researchers noted that E. cloacae complex has a less well defined genetic makeup, compared with K. pneumoniae.

“We hypothesize that E. cloacae complex contains genotypes with epidemic potential associated with increasing rates of carbapenem resistance observed in the VHA,” they wrote, concluding that “the VHA may serve as a vantage point for detecting nationwide trends in antimicrobial drug resistance” (Emerg Infect Dis. 2017 Mar. doi: 10.3201/eid2305.162034 ).