Improved Phenotype-Based Definition for Identifying Carbapenemase Producers among Carbapenem-Resistant Enterobacteriaceae

Emerg Infect Dis. 2015 Sep;21(9):1611-6. doi: 10.3201/eid2109.150198.

Abstract

Preventing 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.

Keywords: CRE; EIP; Emerging Infections Program; Enterobacteriaceae; United States; antimicrobial resistance; bacteria; carbapenem-resistant; carbapenemase; carbapenemase producers; enterobacteria; enterobacterial infection; identification; prevention; surveillance.

Publication types

  • Evaluation Study

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Carbapenems / pharmacology
  • Communicable Disease Control / standards
  • Communicable Diseases, Emerging / epidemiology
  • Communicable Diseases, Emerging / microbiology*
  • Communicable Diseases, Emerging / prevention & control
  • Diagnostic Tests, Routine / standards
  • Drug Resistance, Bacterial*
  • Enterobacteriaceae / drug effects
  • Enterobacteriaceae / enzymology
  • Enterobacteriaceae / isolation & purification*
  • Enterobacteriaceae Infections / epidemiology
  • Enterobacteriaceae Infections / microbiology*
  • Enterobacteriaceae Infections / prevention & control
  • Humans
  • Phenotype
  • Public Health Surveillance
  • United States / epidemiology
  • beta-Lactamases / genetics*
  • beta-Lactamases / metabolism

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Carbapenems
  • beta-Lactamases
  • carbapenemase