Development of a novel chromogenic method, Penta-well test, for rapid prediction of beta(-)lactamase classes produced in clinical Enterobacteriaceae isolates

摘要

We developed a novel chromogenic method, Penta-well test, which enables the rapid detection and classification of beta-lactamases in clinical Enterobacteriaceae isolates. This test is based on a combination of nitrocefin and 3 beta-lactamase inhibitors specific to classes A. B, and/or C, with nitrocefin hydrolysis by beta-lactamases being assessed by optical density measurements at 490 nm. When the cutoff value for each beta-lactamase class was determined (0.09, 0.4, and 0.55 for class A, class B, and class C beta-lactamase producers, respectively), the sensitivity and specificity of classification were 93.5% and 68.8% for class A, 93.8% and 100% for class B, and 86.7% and 100% for class C. respectively. Moreover, this method allowed accurate beta-lactamase classification in 20 of 23 (87.0%) isolates producing plural class of beta-lactamases. Thus, the Penta-well test can provide information that would be useful in the accurate detection and classification of beta-lactamases produced by causative bacteria. (C) 2015 Elsevier Inc. All rights reserved.