2018 Volume 67 Issue 5 Pages 727-733
Recently, the frequency of detection of ESBL-producing Enterobacteriaceae has been increasing, and several rapid detection methods for ESBLs have been developed. The ESBL NDP test, a colorimetric assay described by Nordmann, is very useful because it can be used to detect ESBLs rapidly and accurately. However, in this method, it is necessary to use 20 mmol/L Tris-HCl lysis buffer (BPERII Bacterial Protein Extraction Reagent, Thermo Scientific), which is a commercially available protein extraction reagent, for the extraction of ESBLs within 30 min. In this study, we modified the NDP test to make it more rapid, easy, and inexpensive by using glass beads for extraction (GB test). Then, we evaluated the efficiency of the GB test in comparison with the NDP test as a screening method for ESBLs by comparing the test results using ESBL-producing Enterobacteriaceae strains and other strains. 112 ESBL-producing strains were phenotypically and genotypically identified, and 109 strains that were susceptible to third-generation cephalosporin were tested. The concordance rate between the NDP test and the GB test was 100%. The sensitivity and specificity of both tests were 94.6% and 100%, respectively. Furthermore, with only 30 s needed for enzyme extraction, the GB test significantly shortened the assay time (p < 0.01) in comparison with the NDP test. In conclusion, we confirmed the high efficiency of the GB test as a screening method for ESBLs because it is more rapid, easier, and more cost-effective than the NDP test.
