Evaluation of inhibitor-combination mCIM for detecting MBL-producing Enterobacterales using three MBL inhibitors

• Published in: Journal of medical microbiology Vol. 68; no. 11; pp. 1604 - 1606
• Main Authors: Yamada, Kageto, Sasaki, Masakazu, Imai, Waka, Murakami, Hinako, Morita, Toshisuke, Aoki, Kotaro, Ishii, Yoshikazu, Tateda, Kazuhiro
• Format: Journal Article
• Language: English
• Published: England 01-11-2019
• Subjects: inhibitor combination mCIM; dipicolinic acid; sodium mercaptoacetate; EDTA; metallo-β-lactamase; modified carbapenem inactivation method
• ISSN: 0022-2615; 1473-5644
• DOI: 10.1099/jmm.0.001073

The increase in carbapenemase-producing
(CPE), including metallo-β-lactamase (MBL) producers, is a severe global health concern. Thus, highly sensitive and specific methods for detecting MBL producers are needed. In this study, we tested the detectability of MBL-producing
against three types of MBL inhibitors (sodium mercaptoacetate, SMA; ethylenediaminetetraacetic acid, EDTA; and dipicolinic acid, DPA) used in combination with a modified carbapenem inactivation method (mCIM). These inhibitor-combination mCIMs were tested against 129 CPE (IMP, 93; NDM, 11; KPC, 13; NMC, 1; OXA-48, 11) and 75 non-CPE. For evaluation of MBL inhibitors, we used two concentrations for each of the three inhibitors: DPA (200 and 300 mg l
), EDTA (5 and 10 mM), and SMA (1500 and 3000 mg l
). The overall sensitivities of SMA, EDTA and DPA were 97.1-99.0 %, 81.7-99.0 % and 88.5-96.2 %, respectively. Moreover, each method showed high specificity (99.0-100 %). Although inhibitor-combination mCIMs were highly sensitive and specific for the detection of MBL producers, we found that sensitivity was dependent on the concentration of inhibitors.