Phenotypic detection of Metallo-β-Lactamase in Imipenem resistant Pseudomonas aeruginosa

Khosravi, Yalda and Loke, Mun Fai and Chua, Eng Guan and Tay, Sun Tee and Vadivelu, Jamuna (2012) Phenotypic detection of Metallo-β-Lactamase in Imipenem resistant Pseudomonas aeruginosa. Scientific World Journal, 2012. p. 654939. ISSN 2356-6140, DOI


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Carbapenems are the primary choice of treatment for severe Pseudomonas aeruginosa infection. However, the emergence of carbapenem resistance due to the production of metallo β-lactamases (MBLs) is of global concern. In this study, 90 imipenem-(IPM- or IP-) resistant P. aeruginosa (IRPA) isolates, including 32 previously tested positive and genotyped for MBL genes by PCR, were subjected to double-disk synergy test (DDST), combined disk test (CDT), and imipenem/imipenem-inhibitor (IP/IPI) E-test to evaluate their MBLs detection capability. All three methods were shown to have a sensitivity of 100%. However, DDST was the most specific of the three (96.6%), followed by IP/IPI E-test interpreted based on the single criteria of IP/IPI ≥ 8 as positive (62.1%), and CDT was the least specific (43.1%). Based on the data from this evaluation, we propose that only IRPA with IP MIC > 16 μg/mL and IP/IPI ≥ 8 by IP/IPI E-test should be taken as positive for MBL activity.With the new dual interpretation criteria,the MBL IP/IPI E-test was shown to achieve 100% sensitivity as well as specificity for the IRPA in this study. Therefore, the IP/IPI E-test is a viable alternative phenotypic assay to detect MBL production in IRPA in our population in circumstances where PCR detection is not a feasible option.

Item Type: Article
Additional Information: Department of Medical Microbiology
Uncontrolled Keywords: Phenotypic detection; Metallo-β-Lactamase; Imipenem resistant; Pseudomonas aeruginosa
Subjects: Q Science > Q Science (General)
R Medicine > R Medicine (General)
Divisions: Faculty of Medicine
Depositing User: Ms. Nur Azzura Azzahra Jaafar
Date Deposited: 14 Oct 2014 01:22
Last Modified: 25 Oct 2018 06:59

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