New Subclass B1 Metallo-β-Lactamase Gene from a Clinical Pathogenic Myroides odoratus Strain

Myroides odoratus is a low-virulence opportunistic human pathogen. Infections caused by M. odoratus are not common, but reports are increasing in recent years. The biggest challenge for treatment is its resistance to most antibiotics. In 2015, we isolated a pathogenic multidrug-resistant strain of M. odoratus from a urinary tract infection (UTI) patient's urine sample. To report the experience in managing M. odoratus-related UTI and investigate the genetic mechanism of this carbapenem-resistant strain, we conducted a series of microbiological and molecular studies. The bacterial strain was identified as M. odoratus by 16S rRNA gene sequencing. The minimum inhibitory concentrations (MICs) of 17 antimicrobial agents were determined against this strain. Whole-genome sequencing was performed and screened for possible β-lactamase genes. A β-lactamase gene, bla_MOC, was identified by whole-genome sequencing, then cloned and expressed in Escherichia coli DH5α to characterize its function. Antimicrobial susceptibility testing showed that the strain had relatively low MIC to levofloxacin and sulfamethoxazole/trimethoprim (SMZ/TMP). After unsuccessful empirical therapy, the UTI was controlled by levofloxacin in combination with SMZ/TMP. Whole-genome sequencing identified a subclass B1 metallo-β-lactamase gene, bla_MOC, which conferred resistance to most β-lactams except for aztreonam and cefepime. In conclusion, a new β-lactamase gene, bla_MOC, was found in an isolate of M. odoratus. The broad antimicrobial resistance of this isolate is at least attributed partially to this gene.