Shahandeh Zahra, Kalantrai Narges, Sadighian Farahnaz
Department of Laboratory Sciences, Faculty of Paramedical Sciences, Babol University of Medical Sciences, Babol, Iran.
Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran.
Caspian J Intern Med. 2020 Fall;11(4):426-431. doi: 10.22088/cjim.11.4.426.
A routine phenotypic test has not been recommended for the detection of metallo-β-lactamases (MBLs) producing species such as . The current study was conducted to compare the 2-mercaptopropionic acid (2-MPA) phenotypic method and ertapenem non-susceptibility test with polymerase chain reaction in predicting the production of MBLs in clinical isolates of .
Antimicrobial susceptibility test for beta-lactam antibiotics were performed by disk diffusion method. All isolates which showed inhibition zones of ≤ 22 mm for CAZ and ≤ 27 mm for CTX were considered potential MBLs producing isolates. The production of MBLs was confirmed using 2-MPA compound. Also, susceptibility to ertapenem was evaluated in all isolates. Conventional PCR was performed to detect IMP-1 and/or NDM-1 genes in all potential MBLs producing isolates.
Of 259, 138 (53.3%) isolates were potential MBLs producing bacteria. One hundred and fifteen out of 138 (83.3%) isolates were susceptible to ertapenem. MBLs production was confirmed in 75/138 (54.4%) isolates by 2-MPA phenotypic method. The NDM-1 or/and IMP-1 genes were found in 30/75(40%) and 39/115(33.9%) isolates which were confirmed by 2-MPA and were susceptible to ertapenem, respectively. The sensitivity of 2-MPA method and ertapenem non-susceptibility test compared with PCR were 65.2% and 15.2%, and the specificity was 52.1% versus 82.6%, respectively.
This study demonstrated that the 2-MPA phenotypic method does not have acceptable sensitivity and specificity in comparison with PCR, but its results are more reliable for the detection of MBL producing isolates compared with non-susceptibility to ertapenem.
尚未推荐通过常规表型试验来检测产金属β-内酰胺酶（MBLs）的菌株，如……。本研究旨在比较2-巯基丙酸（2-MPA）表型方法和厄他培南不敏感试验与聚合酶链反应在预测临床分离株中MBLs产生情况方面的效果。
采用纸片扩散法对β-内酰胺类抗生素进行药敏试验。所有对头孢他啶抑菌圈直径≤22mm且对头孢噻肟抑菌圈直径≤27mm的分离株均被视为潜在产MBLs分离株。使用2-MPA化合物确认MBLs的产生情况。此外，还评估了所有分离株对厄他培南的敏感性。对所有潜在产MBLs的分离株进行常规PCR检测IMP-1和/或NDM-1基因。
在259株分离株中，138株（53.3%）为潜在产MBLs细菌。138株中有115株（83.3%）对厄他培南敏感。通过2-MPA表型方法在75/138（54.4%）株分离株中确认了MBLs的产生。分别在75株经2-MPA确认且对厄他培南敏感的分离株中，有30/75（40%）株和39/115（33.9%）株检测到NDM-1或/和IMP-1基因。与PCR相比，2-MPA方法和厄他培南不敏感试验的敏感性分别为65.2%和15.2%，特异性分别为52.1%和82.6%。
本研究表明，与PCR相比，2-MPA表型方法的敏感性和特异性均不可接受，但与厄他培南不敏感试验相比，其结果在检测产MBLs分离株方面更可靠。
