PHENOTYPIC DETECTION OF METALLO-?-LACTAMASE AND CARBAPENEMASE AMONG IMIPENEM RESISTANT ACINETOBACTER BAUMANNII

Chaudhary Anish* and Routray Abhisek

ABSTRACT

Background: Carbapenems are the emperical and last resort of treatment used for Gram negative bacilli including Acinetobacter spp. However; an increase in carbapenem resistance among A. baumannii due to Ambler class B metallo-beta-lactamases (MBL) or class D OXA carbapenamases in recent years is of global concern. So this study was undertaken to detect antimicrobial susceptibility pattern and the presence of carbapenemase and metallo-β-lactamase among the carbapenemase resistant clinical isolates of Acinetobacter baumannii by phenotypic method.Material and Methods: A total of 130 non duplicate clinical isolates of A. baumannii from various clinical specimens were included in this study. Antimicrobial susceptibility test was carried out for all 130 isolates by Kirby Bauer disk diffusion method. Carbapenemase and metallo- β-lactamase production was tested among 76 imipenem resistant isolates of A. baumannii by modified Hodge test and combined disk test respectively. Result: In our study, resistance pattern of A. baumannii was as follows: ampicillin (91.53%), amikacin (63.07%), ceftazidime (73.07%), ciprofloxacin (73.84%), co-trimoxazole (60%), gentamicin (59.23%), imipenem (58.46%), ofloxacin (64.61%), and Piperacillin/Tazobactam(50%). Colistin and tigecycline are 93.84% and 100% sensitive respectively by disk diffusion method. Among 76 imipenem resistant isolates carbapenemase and MBL was detected in 54 (71.05%) isolates and 15 (19.73%) isolates respectively.

Keywords: Acinetobacter baumannii, Carbapenemase, Metallo-?-lactamase, Modified Hodge Test.