Detection of carbapenemases in Enterobacterales susceptible in vitro to meropenem.

Background: Carbapenemase-producing Enterobacterales (CPE) is a global threat. We evaluate the prevalence of CPE among isolates categorized as meropenem-susceptible, but that meet the European Committee on Antimicrobial Susceptibility Testing (EUCAST) screening cut-off values for carbapenemase detection, and analyze the susceptibility of these isolates to new available drugs.

Methods: We analyzed 257 isolates from patients hospitalized in a tertiary hospital in Brazil, from July 2022 to April 2023. Only isolates that met the screening cut-off values established by EUCAST for detection of carbapenemases were analyzed (i.e. meropenem inhibition zones of 25-27mm by disk diffusion). The detection of carbapenemases was performed by immnunochromatographic testing and confirmed by high-resolution melting-PCR (HRM-qPCR).

Results: We identified 12 (4.7%) CPE including 7 KPC, 4 NDM, and 1 OXA-48-like. The isolates were susceptible to ceftazidime-avibactam (72.7%), meropenem-vaborbactam (100%), imipenem-relebactam (63.6%) and ceftolozane-tazobactam (36.4%).

Conclusions: We highlight the importance of tracking carbapenemases for epidemiological control and therapeutic guidance.