Chea, NoraBulens, Sandra N.Kongphet-Tran, ThiphasoneLynfield, RuthShaw, KristinVagnone, Paula SnippesKainer, MarionMuleta, DanielWilson, LucyVaeth, ElisabethDumyati, GhinwaConcannon, CathleenPhipps, Erin C.Culbreath, KarissaJanelle, Sarah J.Bamberg, WendyGuh, Alice Y.Limbago, Brandi M.Kallen, Alexander J.2023-08-032023-08-032015-09Chea N, Bulens SN, Kongphet-Tran T, Lynfield R, Shaw K, Vagnone P, et al. Improved Phenotype-Based Definition for Identifying Carbapenemase Producers among Carbapenem-Resistant Enterobacteriaceae. Emerg Infect Dis. 2015;21(9):1611-1616. https://doi.org/10.3201/eid2109.150198https://doi.org/10.3201/eid2109.150198http://hdl.handle.net/11603/29069Preventing transmission of carbapenemase-producing, carbapenem-resistant Enterobacteriaceae (CP-CRE) is a public health priority. A phenotype-based definition that reliably identifies CP-CRE while minimizing misclassification of non–CP-CRE could help prevention efforts. To assess possible definitions, we evaluated enterobacterial isolates that had been tested and deemed nonsusceptible to >1 carbapenem at US Emerging Infections Program sites. We determined the number of non-CP isolates that met (false positives) and CP isolates that did not meet (false negatives) the Centers for Disease Control and Prevention CRE definition in use during our study: 30% (94/312) of CRE had carbapenemase genes, and 21% (14/67) of Klebsiella pneumoniae carbapenemase–producing Klebsiella isolates had been misclassified as non-CP. A new definition requiring resistance to 1 carbapenem rarely missed CP strains, but 55% of results were false positive; adding the modified Hodge test to the definition decreased false positives to 12%. This definition should be considered for use in carbapenemase-producing CRE surveillance and prevention.6 pagesen-USThis is a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.Public Domain Mark 1.0http://creativecommons.org/publicdomain/mark/1.0/Text