Department of Microbiology, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand.
The Antimicrobial Resistance Interdisciplinary Group (AmRIG), Faculty of Pharmacy, Mahidol University, Bangkok, Thailand.
PLoS One. 2021 Nov 4;16(11):e0259686. doi: 10.1371/journal.pone.0259686. eCollection 2021.
The increasing incidence of carbapenem resistance in Acinetobacter baumannii is a critical concern worldwide owing to the limitations of therapeutic alternatives. The most important carbapenem resistance mechanism for A. baumannii is the enzymatic hydrolysis mediated by carbapenemases, mostly OXA-type carbapenemases (class D) and, to a lesser extent, metallo-β-lactamases (class B). Therefore, early and accurate detection of carbapenemase-producing A. baumannii is required to achieve the therapeutic efficacy of such infections. Many methods for carbapenemase detection have been proposed as effective tests for A. baumannii; however, none of them are officially recommended. In this study, three carbapenemase detection methods, namely, CarbaAcineto NP test, modified carbapenem inactivation method (mCIM), and simplified carbapenem inactivation method (sCIM) were evaluated for phenotypic detection of clinically isolated A. baumannii. The MICs of imipenem, meropenem, and doripenem were determined for 123 clinically isolated A. baumannii strains before performing three phenotypic detections. The overall sensitivity and specificity values were 89.09%/100% for the carbAcineto NP test, 71.82%/100% for sCIM, and 32.73%/33.13% for mCIM. CarbAcineto NP test and sCIM performed excellently (100% sensitivity) when both Class B and Class D carbapenemases were present in the same isolate. Based on the results, the combined detection method of sCIM and CarbAcineto NP test was proposed to detect carbapenemase-producing A. baumannii rather than a single assay, significantly increasing the sensitivity of detection to 98.18%. The proposed algorithm was more reliable and cost-effective than the CarbAcineto NP test alone. It can be easily applied in routine microbiology laboratories for developing countries with limited resources.
鲍曼不动杆菌碳青霉烯类耐药性的发生率不断增加，这是一个全球性的重大问题，因为可供选择的治疗方法有限。鲍曼不动杆菌最重要的碳青霉烯类耐药机制是由碳青霉烯酶介导的酶水解，主要是 OXA 型碳青霉烯酶（类 D），其次是金属β-内酰胺酶（类 B）。因此，需要早期和准确地检测产碳青霉烯酶的鲍曼不动杆菌，以实现此类感染的治疗效果。已经提出了许多碳青霉烯酶检测方法作为鲍曼不动杆菌的有效检测方法；然而，没有一种方法被正式推荐。在这项研究中，评估了三种碳青霉烯酶检测方法，即 CarbAcineto NP 试验、改良碳青霉烯灭活法（mCIM）和简化碳青霉烯灭活法（sCIM），用于表型检测临床分离的鲍曼不动杆菌。在进行三种表型检测之前，测定了 123 株临床分离的鲍曼不动杆菌菌株对亚胺培南、美罗培南和多利培南的 MIC。CarbAcineto NP 试验的总敏感性和特异性值分别为 89.09%/100%，sCIM 为 71.82%/100%，mCIM 为 32.73%/33.13%。当同一分离株同时存在 B 类和 D 类碳青霉烯酶时，CarbAcineto NP 试验和 sCIM 表现出色（敏感性为 100%）。基于这些结果，提出了 sCIM 和 CarbAcineto NP 试验联合检测产碳青霉烯酶鲍曼不动杆菌的方法，而不是单一检测，检测敏感性显著提高到 98.18%。与 CarbAcineto NP 试验单独相比，该算法更可靠且更具成本效益。它可以很容易地应用于资源有限的发展中国家的常规微生物学实验室。
