Rapid meropenem/vaborbactam NP test for detecting susceptibility/resistance in Enterobacterales

Background: The treatment options for infections caused by carbapenem-resistant Enterobacterales (CRE) are extremely scarce nowadays and the development of new Antibiotics does not follow the exponential increase in the dissemination of carbapenem resistance determinants worldwide. Meropenem/vaborbactam was recently approved for clinical use and it has been indicated for treating several infections. Although relatively rare, meropenem/vaborbactam resistance has already been reported in Enterobacterales and its early detection could be a valuable tool for faster clinical decision-making.

Objectives: To develop a rapid test, namely the Rapid MEV NP, for the identification of meropenem/vaborbactam resistance in Enterobacterales.

Methods: The Rapid MEV NP test is based on detection of glucose metabolization occurring upon Bacterial growth in the presence of meropenem/vaborbactam at a concentration of 16/8 mg/L. Bacterial growth is detectable by a colour change of phenol red (from red to yellow) subsequent of the acidification of the medium upon Bacterial growth. A total of 75 Enterobacterales isolates were randomly selected for evaluating the performance of the Rapid MEV NP test.

Results: The test showed 97.2% sensitivity and 93.8% specificity when compared with the reference method. The results are obtained after 3 h of incubation at 35°C ± 2°C, which is a gain of time of at least 15 h (one day in practice) compared with currently used antimicrobial susceptibility testing including broth microdilution methods.

Conclusions: The Rapid MEV NP test, easy to perform and to interpret, showed remarkable performance while providing fast results, and is therefore suitable for implementation in routine clinical microbiology laboratories.