Occurrence of bla genes encoding carbapenem-resistant Acinetobacter baumannii from Intensive Care Unit

Background: The spread of carbapenem-resistant Acinetobacter baumannii is a global concern. Metallo-beta-lactamase (MBL) enzymes cause extensive drug resistance among Gram-negative bacteria. The aim of this study was to investigate the prevalence of metallo β-lactamase (MBL) genes (bla VIM, and blaIMP) among isolated multidrug-resistant A. baumannii. Methods: A total of50 non repetitive carbapenem-resistant A. baumannii were collected from different clinical specimens.Antibiotic susceptibility was done by disk diffusion method. MICs were determined by E test method. The resistant strains were detected for the production of carbapenemases by Modified Hodge Test (MHT) followed by EDTA-disk synergy test was performed for metallo-β-lactamases (MBL) phenotypic detection. Detection of bla VIM, and blaIMP was performed by PCR followed by sequencing. Results: All isolates had a multidrug resistant profile, but remainded susceptible to colistin. Among these isolates, Carbapenemase production was confirmed by Modified Hodge test for 42 (84%) isolates. Phenotypic method showed productions of MBL in 15(30%) isolates.Searching for MBLs genes in all the isolates showed that 13 (26%) were positive for blaVIM and all of them were negative for blaIMP. Conclusion: Our study concludes that high prevalence of carbapenem resistant Acinetobacter species with MBL production is oneof the main concerns in our country and this situation which needs strict infection control measures.

Keywords:

Acinetobacter baumannii , Carbapenem Resistance , Metallo-beta-Lactamases , Modified Hodge Test