Background: Enterobacteriaceae producing extended-spectrum beta-lactamase (ESBL), AmpC, and metallo-beta-lactamases (MBL) have been increasingly reported worldwide. These organisms usually exhibit multidrug resistance that is not always detected in routine susceptibility tests. This leads to uncontrolled spread of ESBL- and AmpC-producing organisms and related treatment failures. Hence, detection of ESBL, AmpC, and MBL is important in the routine clinical laboratory.
Objective: To investigate the presence of different classes of beta-lactamase enzymes in clinical isolates of Enterobacteriaceae.
Materials and Methods: A total of 100 consecutive Enterobacteriaceae, that is, Escherichia coli, Klebsiella spp., Citrobacter spp., and Proteus spp., isolates from various clinical samples were included in this study. Detection of ESBL production was carried out by phenotypic confirmatory test as per Clinical and Laboratory Standards Institute guidelines. AmpC production was detected by AmpC disk test and MBL by EDTA disk potentiation test.
Result: Among the 100 clinical isolates tested, ESBL production was seen in 34 (34%), AmpC in 16 (16%), ESBL and AmpC coproduction in 24 (24%), and MBL in 8 (8%) isolates.
Conclusion: The study emphasizes the high prevalence of multidrug-resistant Enterobacteriaceae producing beta-lactamase enzymes of diverse mechanisms. Thus proper antibiotic policy and measures to restrict the indiscriminative use of cephalosporins and carbapenems should be taken to minimize the emergence of this multiple beta-lactamase-producing pathogens.
Key words: AmpC beta-lactamases, extended-spectrum beta-lactamases, coexistence, prevalence, gram-negative bacteria
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