The MALDI Biotyper Selective Testing of Antibiotic Resistance-β-Lactamase (MBT STAR-BL) assay enables rapid detection of β-lactamase activity using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. The assay is based on analysis of bacterially induced hydrolysis of β-lactam antibiotics. We investigated the performance of the MBT STAR-BL assay for detecting IMP metallo-β-lactamase (MBL) activity in Enterobacteriaceae. A total of 145 strains (30 Escherichia coli, 43 Klebsiella pneumoniae, and 72 Enterobacter cloacae complex) were evaluated using meropenem hydrolysis assays. The MBT STAR-BL correctly identified all 48 IMP MBL producers as positive, even those exhibiting a low minimal inhibitory concentration (MIC) (1 μg/mL) for meropenem. Conversely, all non-IMP MBL producers, including strains with higher MICs (4 or 8 μg/mL), were correctly identified as negative. The MBT STAR-BL is a rapid, accurate, and reliable system for detecting IMP MBL activity in Enterobacteriaceae.
Keywords: Antibiotic resistance; IMP metallo-β-lactamase; MALDI-TOF MS.
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