Abstract
There is an urgent need to be able to identify carbapenemase-producing Enterobacterales. In this study we aimed to compare the performance of the MALDI Biotyper Selective Testing of Antibiotic Resistance-βLactamase (MBT STAR-BL) test with the in-house Carba NP test in their ability to rapidly detect carbapenemase production in Escherichia coli and Klebsiella pneumoniae strains. MBT STAR-BL and Carba NP testing were performed in parallel. One hundred sixty-nine isolates in total were tested. K. pneumoniae (n = 139) and E. coli (n = 14) strains with previously characterized carbapenemase types, and non-carbapenemase-producing strains of K. pneumoniae (n = 8) and E. coli (n = 8), were included in the study. When the results of the ertapenem and meropenem hydrolysis assays were evaluated together, MBT STAR-BL correctly identified 151 out of 153 (99%) carbapenemase producers as positive, while giving false-negative results for OXA-48 and OXA-48+NDM-1 producers in two K. pneumoniae isolates. The specificity and sensitivity of MBT STAR-BL were 100% and 98.69%, respectively. For the Carba NP test we confirmed 100% specificity, but sensitivity was 96.7%, although increasing to 100% when using prolonged incubation timing (4 hours). False-negative results were associated with enzymes with low carbapenemase activity, particularly OXA producers, which are common in Enterobacterales.
Get full access to this article
View all access options for this article.