Department of Clinical Infectious Diseases, Kochi Medical School Hospital, Kochi, Japan; Department of Clinical Infectious Diseases, Aichi Medical University, Aichi, Japan.
Department of Clinical Infectious Diseases, Aichi Medical University, Aichi, Japan; Fukoku CO., LTD, Saitama, Japan.
J Infect Chemother. 2022 Apr;28(4):526-531. doi: 10.1016/j.jiac.2021.12.018. Epub 2022 Jan 10.
BACKGROUND/PURPOSE: Rapid detection of β-lactamases is important in a recent situation where resistant bacteria are increasing. By using the drug susceptibility testing microfluidic device (DSTM), rapid screening of extended spectrum β-lactamases (ESBLs) and metallo-β-lactamases (MBLs) has become possible.
β-lactams and β-lactamase inhibitors were pre-fixed in the DSTM for use. A bacterial suspension in Mueller-Hinton broth (McF 0.25) was introduced into the device, and the effects of β-lactamase inhibitor on morphological changes caused by β-lactam were evaluated after 3 h incubation.
Clinical isolates genetically confirmed to produce β-lactamase were used. Of the 84 ESBL-producing strains, 80 strains (95%) turned to be ESBL positive, and five strains (6%) of them MBL were positive as well as ESBL. Four strains (5%) were negative for both ESBL and MBL. Of the 24 MBL-producing strains, 23 strains (96%) were positive for MBL. All the 43 AmpC-producing strains were negative for both ESBL and MBL. Of the 156 ESBL- and MBL-nonproducing strains, 155 strains (99%) were negative for both ESBL and MBL, and one strain was positive for ESBL. With this method, the detection sensitivity was 95% and the specificity was 100% for ESBL, whereas the detection sensitivity was 96% and the specificity was 98% for MBL. These results were not significantly different from the results of the disc diffusion method.
The DSTM method allows rapid detection of β-lactamases in 3 h and may be a useful replacement for the disc diffusion method.
背景/目的：在耐药菌不断增加的情况下，快速检测β-内酰胺酶变得尤为重要。通过使用药敏试验微流控装置（DSTM），可以快速筛选出扩展谱β-内酰胺酶（ESBLs）和金属β-内酰胺酶（MBLs）。
DSTM 中预先固定了β-内酰胺类药物和β-内酰胺酶抑制剂。将 McF0.25 肉汤中的细菌悬液注入装置中，孵育 3 小时后，评估β-内酰胺酶抑制剂对β-内酰胺引起的形态变化的影响。
使用经过基因确认产生β-内酰胺酶的临床分离株。在 84 株产 ESBL 的菌株中，80 株（95%）为 ESBL 阳性，其中 5 株（6%）同时为 MBL 和 ESBL 阳性，4 株（5%）为 ESBL 和 MBL 双阴性。在 24 株产 MBL 的菌株中，23 株（96%）为 MBL 阳性。所有 43 株产 AmpC 的菌株均为 ESBL 和 MBL 双阴性。在 156 株 ESBL 和 MBL 非产菌株中，155 株（99%）均为 ESBL 和 MBL 双阴性，1 株为 ESBL 阳性。该方法检测 ESBL 的灵敏度为 95%，特异性为 100%，检测 MBL 的灵敏度为 96%，特异性为 98%。这些结果与纸片扩散法的结果无显著差异。
DSTM 法可在 3 小时内快速检测β-内酰胺酶，可能是纸片扩散法的一种有用替代方法。
