Evaluation of the MBT STAR-Carba Assay for the Detection of Carbapenemase Production in Enterobacteriaceae and Hafniaceae with a Large Collection of Routine Isolates from Plate Cultures and Patient-Derived Positive Blood Cultures.

The spread of carbapenemase-producing Enterobacterales is a major public health concern worldwide, and methods for their prompt and reliable detection are highly demanded for therapeutic and hygiene control purposes. In this study, we evaluate the MBT STAR® -Carba assay (Bruker Daltonik) to detect the carbapenemase production in clinical and surveillance isolates from plate cultures and directly from patient-derived positive blood cultures bottles. Overall, n  = 1,307 samples were analyzed ( n  = 900 plate cultures, and n  = 407 positive blood cultures, using the bacterial pellet obtained with the Sepsityper® Kit; Bruker Daltonik), including n  = 793 carbapenemase producers ( n  = 579 Klebsiella pneumoniae carbapenemase, n  = 161 metallo-beta-lactamases, n  = 45 OXA-48, and eight isolates harboring two different enzymes), n  = 239 carbapenem-resistant noncarbapenemase producers, and n  = 275 carbapenem-susceptible strains. The STAR-Carba assay detected 657/661 (99.4%) carbapenemase producers from plate cultures, and 132/132 (100%) from positive blood cultures. Specificity resulted in 100% for carbapenem-susceptible strains, and 91.6% for carbapenem-resistant strains resulted negative for carbapenamase production with the routine methods used in this study. In this study, the MBT STAR-Carba assay proved to be a highly reliable method for the detection of carbapenemase-producing Enterobacterales , regardless of the enzyme family, and from both plate cultures and positive blood culture bottles.