Intestinal Carriage of Carbapenemase-Producing Organisms: Current Status of Surveillance Methods

Abstract

SUMMARYCarbapenemases have become a significant mechanism for broad-spectrum β-lactam resistance inEnterobacteriaceaeand other Gram-negative bacteria such asPseudomonasandAcinetobacterspp. Intestinal carriage of carbapenemase-producing organisms (CPOs) is an important source of transmission. Isolation of carriers is one strategy that can be used to limit the spread of these bacteria. In this review, we critically examine the clinical performance, advantages, and disadvantages of methods available for the detection of intestinal carriage of CPOs. Culture-based methods (Centers for Disease Control and Prevention [CDC] protocols, chromogenic media, specialized agars, and double-disk synergy tests) for detecting carriage of CPOs are convenient due to their ready availability and low cost, but their limited sensitivity and long turnaround time may not always be optimal for infection control practices. Contemporary nucleic acid amplification techniques (NAATs) such as real-time PCR, hybridization assays, loop-mediated isothermal amplification (LAMP), or a combined culture and NAAT approach may provide fast results and/or added sensitivity and specificity compared with culture-based methods. Infection control practitioners and clinical microbiologists should be aware of the strengths and limitations of available methods to determine the most suitable approach for their medical facility to fit their infection control needs.

Carbapenem-Resistant Non-Glucose-Fermenting Gram-Negative Bacilli: the Missing Piece to the Puzzle

“…It does not differentiate resistance mechanisms based on organism type (i.e., glucose nonfermenters and fermenters). All classes of Ambler carbapenemases have been detected in Pseudomonas and Acinetobacter species (15). The most commonly acquired carbapenemases among Acinetobacter spp.…”

“…In contrast, the most commonly encountered carbapenemases among Pseudomonas spp. are class B MBLs, such as VIM and IMP (15,17). Of note, other carbapenemases, such as GES, NDM, and KPC, are now also being detected and reported in both Pseudomonas and Acinetobacter species (4,18).…”

“…Some ␤-lactamase experts disagree and support resistance testing for both infection control measures and for routine diagnostic testing. One reason cited in support of resistance testing is that carbapenemase production among Gram negatives may lead to elevated carbapenem MICs that do not always cross the resistance threshold based on the current clinical breakpoints (15,21). Accordingly, EUCAST has proposed the use of epidemiological breakpoints followed by phenotypic carbapenemase detection among the Enterobacteriaceae to prevent the spread of both phenotypically resistant isolates and isolates with MICs below the resistance cutoff carrying transmissible elements that could further spread to susceptible bacteria.…”

Case Report of Enterobacter cloacae Producing IMP-8 Carbapenemase Isolated from Secretions of Burn Patients and Diabetes Patients with Diabetic Foot

“…IMP of class B MBL is one of the early described carbapenemases in Enterobacteriaceae. Since the first report of IMP-1 in Serratia marcescens from Japan in 1991 (2), IMP carbapenemase have been described worldwide, particularly in Asian countries, such as Japan, Indian, and Korea (1,3). In China, the gene types found in E. cloacae are IMP-1, IMP-4, IMP-8 and IMP-26, and carbapenem resistance in E. cloacae is becoming a great concern in the region (4,5).…”

“…The strains could spread easily between humans and acquire antibiotic resistance through horizontal gene transfer, mediated mostly by plasmids and transposons. The infection of carbapenem-resistant isolates has brought great difficulties in clinical treatment, and the main drug resistance mechanism is the production of carbapenemase (1). Carbapenemases are generally categorized to Ambler class A, B, and D β-lactamases.…”