Isolation of Serratia fonticola producing FONA, a minor extended-spectrum β-lactamase (ESBL), from imported chicken meat in Japan

Abstract

Five novel strains of Serratia fonticola that produce FONA, a minor extended spectrum beta-lactamase (ESBL), were isolated during the routine surveillance of ESBLproducing Enterobacteriaceae in imported chicken meat in Japan in 2017 and 2018. These strains exhibited a clear ESBL phenotype in susceptibility tests carried out in the presence of clavulanic acid; however, they were all negative in the multiplex polymerase chain reaction assay used to detect the TEM, SHV and CTX-M β-lactamase genes. After identification of the bacterial species as S. fonticola, full bla_FONA genes were amplified and the DNA sequences were determined. The bla_FONA genes from all five strains were different from those previously reported (bla_FONA-1 to bla_FONA-6); they clustered closely with one another but were distinct from previously reported blaFONA genes in a phylogenic analysis based on amino acid sequences.