Guclu Aylin U, Gozen Ayse G
Clin Lab. 2020 Oct 1;66(10). doi: 10.7754/Clin.Lab.2020.200135.
This study aimed to investigate the genetic diversity of OXA-51-like, OXA-23-like, OXA-24, and OXA-58-like genes and the role of β-lactamases in carbapenem resistance among multidrug resistant Acinetobacter baumannii strains recovered from patients in intensive care units (ICUs).
Non-duplicate clinical isolates of A. baumannii from ICUs that were identified as imipenem and meropenem resistant were collected. Antimicrobial susceptibilities were determined by PhoenixTM system (Becton Dickinson, USA). Minimum inhibitory concentrations (MICs) for imipenem and meropenem were determined by using gradient strip method (E-test) and interpreted according to CLSI. Presence of carbapenemase activity was determined by the modified Hodge test (MHT) and detection of metallo-β-lactamase (MBL) was performed by the double-disk synergy test (DDST) and MBL E-test. Detection of the four groups of OXA carbapenemase genes (OXA-23, OXA-24, OXA-51, and OXA-58) was carried out using a multiplex PCR assay. Sequencing of the products in both directions was performed by ABI 3130XL genetic analyzer (Life Technologies Corporation, CA, USA). The resulting DNA sequence was analyzed by the BLAST program, available at the NCBI website.
Sixty-one non-duplicate, multidrug resistant clinical A. baumannii isolates were studied. MHTs were positive for all 61 A. baumannii strains, but none of them showed MBL activity. As determined through multiplex PCR, all of the 61 isolates had blaOXA-51 genes including blaOXA-64, blaOXA-66, and blaOXA-91, 50 isolates had blaOXA-23, and 11 isolates had blaOXA-58 genes. Alleles encoding OXA-24-like enzymes were not detected in any isolates.
This study indicated that the major cause of carbapenem resistance in our region was OXA-type car-bapenemase encoded by blaOXA-51, blaOXA-23, and blaOXA-58 genes and as we know, this is the first report from Turkey identifying blaOXA-51-like sequences.
本研究旨在调查从重症监护病房（ICU）患者中分离出的多重耐药鲍曼不动杆菌菌株中OXA-51样、OXA-23样、OXA-24和OXA-58样基因的遗传多样性，以及β-内酰胺酶在碳青霉烯类耐药中的作用。
收集ICU中鉴定为对亚胺培南和美罗培南耐药的非重复鲍曼不动杆菌临床分离株。采用PhoenixTM系统（美国BD公司）测定抗菌药物敏感性。采用梯度纸条法（E-test）测定亚胺培南和美罗培南的最低抑菌浓度（MIC），并根据CLSI标准进行判读。采用改良Hodge试验（MHT）测定碳青霉烯酶活性，采用双纸片协同试验（DDST）和MBL E-test检测金属β-内酰胺酶（MBL）。采用多重PCR检测四组OXA碳青霉烯酶基因（OXA-23、OXA-24、OXA-51和OXA-58）。使用ABI 3130XL基因分析仪（美国加利福尼亚州Life Technologies公司）对产物进行双向测序。所得DNA序列通过NCBI网站上的BLAST程序进行分析。
研究了61株非重复的多重耐药鲍曼不动杆菌临床分离株。所有61株鲍曼不动杆菌菌株的MHT均为阳性，但均未显示MBL活性。通过多重PCR测定，61株分离株均有blaOXA-51基因，包括blaOXA-64、blaOXA-66和blaOXA-91，50株有blaOXA-23基因，11株有blaOXA-58基因。在任何分离株中均未检测到编码OXA-24样酶的等位基因。
本研究表明，我们地区碳青霉烯类耐药的主要原因是由blaOXA-51、blaOXA-23和blaOXA-58基因编码的OXA型碳青霉烯酶，据我们所知，这是土耳其首次鉴定出blaOXA-51样序列的报告。
