Characterization and Identification of a novel chromosome-encoded metallo-β-lactamase WUS-1 in Myroides albus P34

In this study, we identified and characterized a novel chromosomally-encoded class B metallo-β-lactamase (MBL) gene designated bla(WUS-1) in a carbapenem-resistant isolate Myroides albus P34 isolated from sewage discharged from an animal farm. Comparative analysis of the deduced amino acid sequence revealed that WUS-1 shares the highest amino acid similarities with the function-characterized MBLs MUS-1 (AAN63647.1; 70.73%) and TUS-1 (AAN63648.1; 70.32%). The recombinant carrying bla(WUS-1) exhibited increased MICs levels against a number of β-lactam antimicrobials such as carbenicillin, ampicillin and imipenem, and β-lactamase inhibitors (clavulanic acid and tazobactam). The metallo-β-lactamase WUS-1 could also hydrolyze these antimicrobials and the hydrolytic activities could be inhibited by EDTA. Genetic context analysis of bla(WUS-1) revealed that no mobile genetic element was found in its surrounding region. The plasmid pMA84474 of Myroides albus P34 harbored 6 resistance genes (bla(OXA-347), aadS, bla(MYO-1), ereD, sul2 and ermF) within an approximately 17 kb multidrug resistance (MDR) region. These genes, however, were all related to mobile genetic elements.