Purification and characterization of an imipenem hydrolysing metallo-β-lactamase from Bacteroides fragilis

An imipenem resistant β-lactamase producing strain of Bacteroides (fragilis was isolated from a clinical specimen. The specific activity of the unpurified β-lactamase was 5.5 U/mg protein. The β-lactamase was purified 60-fold by Q Sepharose, Sephacryl S-300 and Mono Q column passages. The strain was able to inactivate imipenem and cefoxitin in broth cultures. The enzyme hydrolysed imipenem more rapidly than ampicillin, benzylpenicillin, cephalothin and cefoxitin. The activity of the enzyme was Zn 2+ dependent and was completely inhibited by EDTA