Evaluation of Two Commercial Kits for Rapid Detection and Typing of Carbapenemase in Carbapenem-Resistant Enterobacterales

Seunghoo Lee1   Kyu-Hwa Hur1   Yunsil Chung1   Heungsup Sung1   Mi-Na Kim1   

1 Departments of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul,

* Corresponding author: Tel: +82-2-3010-4511, Fax: +82-2-478-0884, E-mail: mnkim@amc.seoul.kr

Abstract

Background: Rapid detection of carbapenemase-producing Enterobacterales (CPE) is desirable to guide antimicrobial therapy and infection control. The NG-Test Carba5 (Carba5; NG Biotech, France) rapid multiplex lateral flow immunoassay and BD MAX Check-Points CPO Assay (CPO; BD Diagnostic Systems, USA) fully automated real-time PCR assay were evaluated for the detection of KPC, NDM, VIM, IMP, and OXA-48-like group in a culture colony compared to genotyping using conventional PCR.

Methods: Among the clinical isolates of carbapenem-resistant Enterobacterales (CRE) collected from 2013 to 2019, up to 20 isolates for each carbapenemase type, and approximately 60 carbapenemase-negative CRE were enrolled. Genotyping of carbapenemases were performed using single-target PCR for KPC, NDM, and OXA-48-like group and the multiplex PCR for VIM, IMP, GIM, SIM, and SPM. All isolates were tested with Carba5 and CPO. The discrepant results were resolved by single-target specific conventional PCR or GeneXpert Carba-R Assay (Carba-R; Cepheid, USA).

Results: Of 147 CREs, 82 were CPE (55.8%) including 20 KPC, 22 NDM, 17 VIM, three IMP, and 13 OXA-48-like group, and seven double carbapenemase-positive (three KPC/VIM, two NDM/VIM, one KPC/NDM, and one NDM/OXA-48-like group) isolates. Carba5 and CPO detected all CPE correctly along with two more IMP-producing CPE. The sensitivity and specificity of both kits were equally 100% and 97%. Two false IMP-positives were confirmed IMP-positive with Carba-R and IMP-specific single-target PCR.

Conclusion: Carba5 and CPO reliably detect and differentiate five common carbapenemases in cultured colonies. Carba5, faster and simpler, is preferred as a spot test.

Figures & Tables

Table 1Primer sequences for the carbapenemase genotyping