Genetic and Biochemical Characterization of VMB‐1, a Novel Metallo‐β‐Lactamase Encoded by a Conjugative, Broad‐Host Range IncC Plasmid from Vibrio spp

Abstract The increasing incidence of phenotypic resistance to carbapenems in recent years is mainly attributed to acquisition of mobile carbapenemase‐encoding genetic elements by major bacterial pathogens. Here, a novel carbapenemase known as Vibrio metallo‐β‐lactamase 1 (VMB‐1), which is encoded by a gene ( bla VMB‐1 ) located in an integron‐bearing, highly transmissible IncC type plasmid, namely pVB1796, is identified and characterized, both genetically and functionally. Recovered from a foodborne Vibrio alginolyticus strain that exhibits resistance to all known β‐lactam antibiotics, pVB1796 is found to possess a hybrid backbone that exhibits unique features of both type 1 and type 2 IncC elements. VMB‐1 exhibits 94% sequence homology with several recently reported but poorly characterized metallo‐β‐lactamases (MBLs) produced by the marine organisms Alteromonadaceae , Glaciecola , and Thalassomonas actiniarum . Sequence alignment analysis shows that VMB‐1 shares a structurally identical active site with subclass B1 MBLs. Importantly, pVB1796 is found to be efficiently transferred from Vibrio to other Gram‐negative bacterial pathogens, including Salmonella typhimurium , Klebsiella pneumoniae , and Acinetobacter baumanni , via conjugation. These findings suggest that bla VMB‐1 ‐bearing plasmids have the potential to be disseminated to other Gram‐negative bacterial pathogens in the near future and render carbapenems useless in treatment of multidrug resistant infections.