
Saba Choudhary, Kanishtha Sharma, Aishiya Ishrat, Bashir Ahmad Fomda
Comparison of Phenotypic Methods for Detection of Metallo-Beta- Lactamases in Gram Negative Bacteria at a Tertiary Care Hospital
Int.J.Adv.Microbiol.Health.Res.2018; 2(3):51-58
Publisher: IJAMHR, Category: Current Issues
Abstract
Metallo-β-lactamase (MBL)-producing bacteria lead to resistance to carbapenem an
antibiotic that is used as the last resort for treatment of multidrug-resistant bacteria,
extended spectrum beta-lactamases, and AmpC β-lactamase-producing Gram-negative
bacteria (GNB). The emergence of MBL-producing GNB is challenge to microbiology
laboratories because there are no standardized guidelines available to detect them. The aim
of this study was to compare three phenotypic methods to detect MBL production in GNB
and to determine antibiotic sensitivity of MBL-producing isolates. A total of 250 GNB
isolated from various clinical samples were tested for MBL production. All isolates were
subjected to antibiotic susceptibility testing. Out of 250 isolates, 130 Imipenem (IPM)-
resistant clinical isolates were taken as positive for MBL screening which were then
subjected to confirmation by three phenotypic methods including Combined Disc test, MIC
and Carba NP test. Out of 130 GNB, 112(86%) isolates were Carba NP positive for MBL
production whereas the 18(13.8%) were negative for the enzyme. CDST and MIC, done for
the presence of MBL enzyme revealed 104(80%) isolates to be positive for its presence
whereas 26(20%) isolates were negative. In this study Carba NP test was found to be most
sensitive and rapid method.
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