Detection of oxacillanase and metallobetalactamase in carbapenem resistant isolates of Acinetobacter spp., from various clinical samples by phenotypic and genotypic methods in a tertiary care hospital

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Original Article

Author Details : Gomathi Maniyan, Dillirani Vedachalam, Nithya Chinnusamy

Volume : 4, Issue : 1, Year : 2017

Article Page : 26-30

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Abstract

Background: Non fermenting Gram Negative Bacilli (NFGNB) once considered as contaminants, now emerged as a major cause of life threatening nosocomial infections and as multidrug resistant pathogens. Acinetobacter species are the opportunistic pathogens with increasing prevalence in the nosocomial infections. Community acquired infections are also common in Acinetobacter. It accounts for 10% of all community-acquired bacteraemic pneumonias.
Aim: To isolate, identify and detect Carbapenem resistance producing Acinetobacter spp., and confirm Oxacillanase (OXA) and Metallo Beta Lactamase (MBL) production by phenotypic& genotypic methods.
Materials and Methods: This cross sectional study conducted in a tertiary care hospital for a period of one year and samples collected like pus, urine, endotracheal aspirates, blood, sputum and body fluids were identified using standard protocol, which includes Gram staining, test for motility, catalase test, oxidase test, OF test and various biochemical reactions. The resistant strains of Acinetobacter species as identified by phenotyping were subjected to molecular analysis of OXA-51, VIM and IMP genes.
Results: Out of 110 isolates of non-fermenters, Acinetobacter baumannii accounted for 36 (81.8%) and Acinetobacter lwoffi 8 (18.2%). The antimicrobial susceptibility pattern revealed maximum resistance to Gentamycin (50%), Cotrimoxazole (47%), followed by Ciprofloxacin (50%) and Cefotaxime (32.2%). Sensitivity to Polymyxin B (100%) followed by Imipenem and Meropenem (75.5%). MBL production was 20.5%. Molecular characterization of MBL of Acinetobacter species revealed, OXA-51 (33.3%), 3 (33.3%) for bla IMP. and 2(22.2%) isolates blaVIM positive.
Conclusion: Acinetobacter baumannii were the most common isolate in this study. Differences in antimicrobial susceptibility pose a great problem in treating these infections. MBL production by these organisms leads to high morbidity and mortality and left with the only option of treating them by potentially toxic drugs like Colistin and Polymyxin B.

Keywords: Acinetobacter, Metallo Beta Lactamase, OXA, IMP, VIM Gene

How to cite : Maniyan G, Vedachalam D, Chinnusamy N, Detection of oxacillanase and metallobetalactamase in carbapenem resistant isolates of Acinetobacter spp., from various clinical samples by phenotypic and genotypic methods in a tertiary care hospital. Indian J Microbiol Res 2017;4(1):26-30

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