Objective: Metallo-β-lactamase-producing Enterobacterales is widely distributed and confers resistance to all β-lactams, including carbapenems. Recently, a cefepime-taniborbactam combination has been developed that aims to provide a treatment option for infections caused by metallo-β-lactamase-producing bacteria. The objective of this study was to develop a rapid diagnostic test, namely the Rapid Cefepime-Taniborbactam NP test, for the early identification of cefepime-taniborbactam susceptibility or resistance in Enterobacterales.

Methods: The Rapid Cefepime-Taniborbactam NP test is based on the detection of glucose metabolism resulting from bacterial growth, detectable by a change in colour of a red phenol (from red to yellow) in the presence of cefepime-taniborbactam. A total of 103 Enterobacterales isolates, including 94 carbapenemase producers, were selected for evaluation of the performance of the Rapid Cefepime-Taniborbactam NP test. In the absence of available breakpoints, two provisional breakpoints were taken for the interpretation-one corresponding to the current Clinical and Laboratory Standards Institute cefepime resistance breakpoint (R ≥ 16 mg/L) and one following current literature on this combination (R ≥ 32 mg/L).

Results: The test demonstrated a sensitivity and specificity of 95% and 98%, respectively, following a resistance breakpoint of ≥16 mg/L. When considering a resistance breakpoint of ≥32 mg/L, the sensitivity and specificity were found to be 100% and 91%, respectively. All results were obtained within a 3 h incubation period at 35°C ± 2°C, representing a significant reduction in time compared with current antimicrobial susceptibility testing methods.

Conclusions: The results of this study demonstrate that the Rapid Cefepime-Taniborbactam NP test is a highly accurate and time-efficient technique for the detection of bacterial resistance.