Wan Nor Amilah W A W, Noor Izani N J, Ng W K, Ashraful Haq J
School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.
Trop Biomed. 2012 Dec;29(4):588-97.
Clinical utilization of carbapenems remains under threat with the emergence of acquired carbapenemase-producing bacteria, particularly metallo-β-lactamases (MBL). Rapid detection of MBL-producing Gram-negative bacilli is essential to prevent their widespread dissemination. However, no standardized detection method is available for routine laboratory use. The purpose of the study was to evaluate a chelating-agent based double disk synergic test and disk potentiation test for MBL-producing strain detection and to determine the isolation rate of MBL-producing Pseudomonas aeruginosa and Acinetobacter from clinical samples in our tertiary teaching hospital. A total of 22 and 66 imipenem-resistant P. aeruginosa and Acinetobacter isolates respectively were tested with ceftazidime (CAZ) disk by modified double disk synergic test and disk potentiation test using ethylenediaminetetraacetic acid (EDTA) and 2-mercaptopropionic acid (as chelating agents) to detect MBL production. The tests were compared with EDTA-phenanthroline-imipenem (EPI) microdilution MIC test as gold standard. MBL positive strains were detected in 17 (77.3%) P. aeruginosa and 2 (3.5%) Acinetobacter isolates. The disk potentiation test with 2-mercaptopropionic acid (2-MPA) dilution of 1:12 provided the most acceptable sensitivities and specificities (88.2% sensitivity and 100% specificity in P. aeruginosa; 100% sensitivity and specificity in Acinetobacter) compared to other screening methods used in this study. This study provided useful information on the local prevalence of MBL-producing P. aeruginosa and Acinetobacter in our hospital. Disc potentiation test with CAZ/2-MPA disc appears to be reliable and convenient MBL detection method in the routine clinical laboratory.
随着产碳青霉烯酶细菌的出现，尤其是金属β-内酰胺酶（MBL）的出现，碳青霉烯类药物的临床应用仍然受到威胁。快速检测产MBL的革兰氏阴性杆菌对于防止其广泛传播至关重要。然而，目前尚无适用于常规实验室使用的标准化检测方法。本研究的目的是评估基于螯合剂的双纸片协同试验和纸片增效试验用于检测产MBL菌株，并确定在我们的三级教学医院临床样本中产MBL的铜绿假单胞菌和不动杆菌的分离率。分别使用乙二胺四乙酸（EDTA）和2-巯基丙酸（作为螯合剂），通过改良的双纸片协同试验和纸片增效试验，用头孢他啶（CAZ）纸片对总共22株耐亚胺培南的铜绿假单胞菌和66株耐亚胺培南的不动杆菌分离株进行检测，以检测MBL的产生。将这些试验与作为金标准的EDTA-邻菲罗啉-亚胺培南（EPI）微量稀释MIC试验进行比较。在17株（77.3%）铜绿假单胞菌和2株（3.5%）不动杆菌分离株中检测到MBL阳性菌株。与本研究中使用的其他筛查方法相比，用1:12稀释的2-巯基丙酸（2-MPA）进行纸片增效试验提供了最可接受的敏感性和特异性（铜绿假单胞菌的敏感性为88.2%，特异性为100%；不动杆菌的敏感性和特异性均为100%）。本研究提供了关于我院产MBL的铜绿假单胞菌和不动杆菌的当地流行情况的有用信息。用CAZ/2-MPA纸片进行纸片增效试验似乎是常规临床实验室中可靠且方便的MBL检测方法。
