Molecular and Bacteriological Detection of Multi-drug resistant and Metallo- β -Lactamase Producer Acinetobacter baumannii in Ramadi City, West of Iraq

Abstract

Background: One leading factor responsible for resistance in Acinetobacter baumannii, is the production of carbapenamases like metallo-β-lactamases (MBLs), which hydrolyze a variety of β-lactams including penicillin, cephalosporins and carbapenems. This study aims to evaluate phenotypic method against genotypic, PCR as gold standard test among carbapenem resistant A. baumannii for identifying MBL producers. Patients and Methods: One hundred and eighty-eight of 213 patients were culture positive (88.26%). Forty-four Acinetobacter baumannii clinical isolates were chosen for this study. Phenotypic expression of MBL was detected by IPM-EDTA-disk synergy test and presence of blaIMP-1 and blaIMP was detected by PCR for all metallo- β -lactamase producing Acinetobacter baumannii. Results: Forty-one (93.2%) isolates of Acinetobacter baumannii (out of 44 isolates) were found to be MBL producers by IPM-EDTA-disk synergy test. Thirty-five (80%) Acinetobacter baumannii of 44 presumptive MBL producer isolates (with isolates were negative for MBL producer in phenotypic method used as control) were positive for bla IMP-1 gene by PCR, while twelve (27.3%) Acinetobacter baumannii out of 44 presumptive MBL producer isolates (with isolates were negative for MBL producer in phenotypic method used as control) were positive for blaIMP gene by PCR. The coexistence of blaIMP-1 with blaIMP genes in present study 25% (11/44) of cases. Conclusion: Most isolates of Acinetobacter baumannii were found to be metallo beta lactamase (MBL) producers using IPM-EDTA-disk synergy test. Further, isolates of A. baumannii have been produced MBL gene (bla IMP-1). It seems to be the major mechanism of resistance among Iraqi nosocomial isolates of A. baumannii. Key words: Multidrug-resistant, Acinetobacter baumannii, Metallo- β –lactamase (MBL), Imipenem