Novel β-Lactamase bla ARL in Staphylococcus arlettae

Whole-genome sequencing of penicillin-resistant Staphylococcus arlettae strain SAN1670 from bovine mastitis milk revealed a novel β-lactamase operon consisting of the β-lactamase-encoding gene bla ARL , the antirepressor-encoding gene blaR1 ARL , and the repressor-encoding gene blaI ARL . The functionality of bla ARL was demonstrated by gene expression in Staphylococcus aureus . The bla ARL operon was chromosomally located in SAN1670 and present in 10 additional unrelated strains, suggesting intrinsic penicillin resistance in S. arlettae . Furthermore, a GenBank search revealed more unique potential β-lactamases in Staphylococcus species. IMPORTANCE Penicillins are an important group of antibiotics used to treat various types of infections caused by Gram-positive bacteria. So far, the blaZ gene was the only known β-lactamase gene in staphylococci. However, other putative β-lactamases were identified, and one of them was shown to be a novel functional β-lactamase encoded by bla ARL in Staphylococcus arlettae , further limiting treatment options.