Carbapenemase-producing Enterobacteriaceae in animals and methodologies for their detection

Abstract

Carbapenemase-producing bacteria are difficult to treat and pose an important threat for public health. Detecting and identifying them can be a challenging and time-consuming task. Due to the recent rise in prevalence of infections with these organisms, there is an increased demand for rapid and accurate detection methods. This review describes and contrasts current methods used for the identification and detection of carbapenemase-producing bacteria to help control their spread in animal populations and along the food chain. The methods discussed include cultures used for screening clinical samples and primary isolation, susceptibility testing, culture-based and molecular confirmation tests. Advantages and disadvantages as well as limitations of the methods are discussed.

Figure 1

Structure of thienamycin, the first described, naturally produced carbapenem [adapted from (2)].

Figure 2

Base structure of carbapenemase with a — β-lactam ring shown in blue, variable R₁ region present in all carbapenemases shown in red, and variable R₂ region present in meropenem, doripenem, and ertapenem shown in green; b — R₁ group for imipenem; and c — R₁ and applicable R₂ groups for meropenem, ertapenem, doripenem, and biapenem. Molecular structures were adapted from (2).

Figure 3

Carbapenem-resistant Enterobacteriaceae (CRE) confirmation tests based on inactivation of carbapenemases: a — modified Hodge test using a meropenem disk (test strains counter-clockwise from top: NDM-producer, KPC-producer, OXA-48-producer, and CMY-producer); and b — carbapenemase inactivation method (counter-clockwise from top right: NDM-producer, KPC-producer, OXA-48-producer, and CMY-producer).