A fatal case of peritonitis caused by Dysgonomonas capnocytophagoides harboring the novel metallo-beta-lactamase gene blaDYB-1.

Dysgonomonas capnocytophagoides shows multidrug resistance to antibiotics and causes opportunistic infections in immunocompromised hosts. The drug resistance mechanisms of D. capnocytophagoides have not yet been identified. In this work, we analyzed D. capnocytophagoides isolated from a fatal case of peritonitis to clarify its drug resistance mechanisms. Whole genome sequencing revealed that our isolate harbored a chromosomally encoded metallo-beta-lactamase (designated blaDYB-1) and a chromosomally encoded ermFS gene. Phylogenetic analysis, primary sequence comparison, and structural modeling analysis of DYB-1 showed it was highly similar to CfiA in Bacteroides fragilis and belonged to the B1 MBL family. Transformation analysis into Escherichia coli TOP10 showed that a recombinant plasmid containing blaDYB-1 increased the minimum inhibitory concentration of beta-lactams, including carbapenem. We identified a novel chromosomally encoded class B1 metallo-beta-lactamase gene designated blaDYB-1 and an ermFS gene that contributed to multidrug resistance. This study indicates the importance of further surveillance for D. capnocytophagoides harboring blaDYB-1.