Rapid and accurate eXDR screening: use Xpert Carba-R with FecalSwab
ABSTRACT
The FecalSwab® displays high performances for stool culture, but it was not assessed for carbapenemase-producing Enterobacterales (CPE) screening. We assess the performances of the Xpert Carba-R v2® with the FecalSwab®. Using a collection of 12 CPE strains, the limit of detection was assessed at 158 CFU/swab [interquartile range 93–589]. In 2019, 1540 swabs were included by 4 hospital laboratories, of which 39 (2.5%) yield an invalid result. Among the 1501 valid, 87 (5.8%) were positives by culture and PCR and 25 (1.7%) were discrepant: 7 PCR-negative culture-positive, and 18 PCR-positive culture-negative. Two PCR-positive culture-negative results involved non-Enterobacterales strains: a KPC-producing Acinetobacter baumannii and a KPC-producing Aeromonas spp. The overall percent agreement was 98.3% and the Kappa value was 0.88. FecalSwab® is an accurate sampling device for CPE screening. It allows performing all eXDR screening using a single swab, simplifying the sample collection, and improving the patient comfort. Regarding discrepant, we suggest combining a CPE screening by both culture and Xpert Carba-R v2® methods.
Introduction
Accurate identification of eXDR (emerging extensively drug-resistant organisms) carriers, that is, carbapenemase-producing Enterobacterales (CPE) and vancomycin-resistant enterococcus (VRE) carriers, is needed in order to implement eXDR-specific infection prevention and control (IPC) measures and avoid cross-transmission (Banach et al. 2018; Lepelletier et al. 2015; Magiorakos et al. 2017a). As the culture on selective media needs at least 24 to 48 hours, a rapid and robust method is required. The Xpert Carba-R v2 is a fully-integrated molecular method that provides accurate results within less an hour (Saliba et al. 2020). However, as it detects about 95% of all known carbapenemase genes and antimicrobial susceptibility testing is required, a culture remains needed (Dortet et al. 2017). Thus, rapid eXDR screening requires both a fullyintegrated molecular method and a conventional culture using selective media.
According to the manufacturer recommendations, Xpert Carba-R v2 should be performed on rectal or perirectal swabs sampled using the Transystem double swab (TDS) (Copan, Brescia, Italy). Consequently, at least 2 swabs are required in order to perform an eXDR (VRE plus CPE) screening. The FecalSwab (Copan, Brescia, Italy) combines a flocked swab with 3 mL of Cary-Blair medium. It displays high performances for stool culture (Goneau et al. 2019). The accuracy of Xpert Carba-R v2 using FecalSwab has never been assessed yet. In the present study, we aim to assess the limit of detection of the Xpert Carba-R v2 with the FecalSwab and its performances in routine use.
Read More
Full Scientific Study
Date
November 4, 2021
Conference or Journal
Diagnostic Microbiology and Infectious Disease 99 (2021) 115279
Author(s)
Eric Farfoura
Alexandra Lomontb
Vincent Fihmanc
Marion Lecurua
Sophie H€usslerc
Souad Ouzanid
Jean-Ralph Zaharb
Laurent Dortet