A study on carbapenem resistance and metallo-betalactamase production among clinical isolates of Acinetobacter baumanii in a tertiary care hospital

AIM The determine the carbapenem resistance among the various clinical isolates of Acinetobacter baumanii by both disc diffusion and minimum inhibitory concentration( MIC) method and to detect metallobetalactamase production among carbapenem resistant Acinetobacter baumanii isolates by phenotypic methods MATERIALS AND METHODS A total of 100 Acinetobacter baumanii were isolated from various specimens for a period of 4 months . These isolates were subjected to Kirby Bauer disc diffusion test as per CLSI guidelines. All strains resistant to meropenem by disc diffusion were considered to be carbapenemase producer and MIC for all meropenem resistant strains were done by macrobroth dilution method. All the carbapenem resistant strains were screened for Metallobetalactamse production by the Modified Hodge Test (MHT) and Imipenem Imipenem EDTA Combined Disc Test (CDT). Appropriate control strains were used while performing all the test. RESULTS The frequency of carbapenem resistance among the Acinetobacter baumanii isolates was (22).The disc diffusion test correlated with the MIC results.36.4 of MBL production was detected among carbapenem resistant isolates by Combined Disc Test. The Modified Hodge test were negative among the strains which were positive by Combined Disc Test. Majority of the MBL producers were among the urinary isolates. CONCLUSION The combined disc test is a simple method ,which can be used as initial screening test for routine phenotypic dectection of MBL production in any laboratory settings.