Comparative Evaluation of Four Phenotypic
Tests for Detection of Metallo-ß-Lactamase
and Carbapenemase Production in
Acinetobacter baumannii
Published: May 1, 2014 | DOI: https://doi.org/10.7860/JCDR/2014/.4317
Aparna Shivaprasad, Beena Antony, Poornima Shenoy
1. Assisstant Professor, Department of Microbiology, MVJ Medical College, Bengaluru, Karnataka, India.
2 Professor, Department of Microbiology, Father Muller Medical College, Mangalore, Karnataka, India.
3. Professor, Department of Microbiology, MVJ Medical College, Bengaluru, Karnataka, India.
Correspondence
Dr. Beena Antony,
Professor, Department of Microbiology, Father Muller Medical College, Mangalore,
Karnataka-575002, South, India.
Phone: +919448024684, E-mail: beenafmmc@gmail.com
Introduction: Acinetobacter baumannii is an emerging multi-drug resistant opportunistic pathogen that causes a variety of nosocomial infections. In recent years, carbapenem resistance in A.baumannii has increased due to Ambler class B Metallo ß-lactamases or class D OXA Carbapenemases.
Objective: The present study was undertaken to detect and compare the various phenotypic methods for MBL production in nosocomial A.baumannii isolates. Materials and Methods: One hundred sixty eight A.baumannii isolates were subjected to disc diffusion assay. Imipenem resistant isolates were subjected to 4 different phenotypic tests. MBL screening was done by Imipenem-EDTA double disc synergy test, Imipenem-EDTA combined disc test, Modified Hodge test and MBL E-test.
Results: Out of 168 A.baumannii isolates, 85 (50.59%) were imipenem resistant. Among these 85 isolates, 57 (67.05%) were MBL positive by DDST, 69 (81.18%) by CDT, 85 (100%) by MHT and all these 85 isolates were confirmed to be MBL positive by MBL E-test method.
Conclusion: Combined disc test, Modified Hodge test & E-test are equally effective to detect MBL production. However, considering the cost constraints of E-test, simple MHT and CDT can be used. They are easy, economical and can be incorporated into routine testing in laboratories to monitor the emergence of MBLs in MDR A.baumannii.
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