Publication

Abstract : Background and objectives: The predominant Acinetobacter spp. in clinical settings are the members of the Acinetobacter calcoaceticus- baumannii complex which are multi drug resistant and are responsible for causing outbreaks. Carbapenem resistance due to metallo-β-lactamase production in Acinetobacter spp. is on the rise. We investigated the production of carbapenemase among the meropenem resistant Acinetobacter spp. which were further screened for metallo-β-lacatmase production. The co-resistance to other classes of antibiotics was also investigated. materials and methods: Forty five non duplicate consecutive meropenem resistant Acinetobacter calcoaceticus- baumannii complex were investigated for carbapenemase production by the modified Hodge test. The carbapenemase producing isolates were further screened for metallo-β-lacatmase production by the combined disc diffusion test by using imipenem with EDTA as the chelator. The co-resistance to other classes of antibiotics was also investigated to identify the multi drug resistant isolates. results: Of the 45 non duplicate consecutive meropenem resistant Acinetobacter calcoaceticus- baumannii complex which were screened, 95% (43/45) of them were multi drug resistant and 71% (32/45) were found to be carbapenemase producers by the modified Hodge test, of which 21% (7/32) were found to be metallo-β-lacatmase producers phenotypically by the combined-disk test. Conclusion: Carbapenem resistance in Acinetobacter calcoaceticus-baumannii complex is very high and is predominantly due to carbapenemase production. However, metallo-β-lactamase production among these isolates is not very high but is gradually increasing. Only 21% of our isolates were metallo-β-lactamase phenotypes, thus suggesting that the production of carbapenem hydrolyzing oxacillinase is still the most common mechanism of resistance to carbapenems in this species.