The Phenotypic Detection Of Carbapenemase In Meropenem Resistant Acinetobacter Calcoaceticus–Baumannii Complex In A Tertiary Care Hospital In South India 223-226
Dr.V.Anil Kumar MD (Microbiology) Clinical Assistant Professor Department of Microbiology Amrita Institute of Medical Sciences Ponekara, Kochi,Kerala India: 682041. email@example.com Office:0484 2801234 (Extn : 8010,8015] Mob: 09037401413
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.