RAA Enzyme Is a New Family of Class A Extended-Spectrum beta-Lactamase from Riemerella anatipestifer Strain RCAD0122

Whole-genome sequencing of Riemerella anatipestifer isolate RCAD0122 revealed a chromosomally located beta-lactamase gene, bla(RAA-1), which encoded a novel class A extended-spectrum beta-lactamase (ESBL), RAA-1. RAA-1 shared <= 65% amino acid sequence identity with other characterized beta-lactamases. The kinetic assay of native purified RAA-1 revealed ESBL-like hydrolysis activity. Furthermore, bla(RAA)(-1), could be transferred to a homologous strain by natural transformation. However, an epidemiological study showed that the bla(RAA)(-1) gene is not prevalent currently.