Occurrence and Variability of the Efflux Pump Gene across the Genus.

NorA is one of the main native MDR efflux pumps of , contributing to reduced susceptibility towards fluoroquinolones and biocides, but little is known about its variability within or its distribution and conservation among other staphylococci. We screened for sequences homologous to and found it in 61 out of the 63 species described. To the best of our knowledge, this is the first study to report the occurrence of across the genus. The phylogenetic tree follows the evolutionary relations of staphylococci and the closely related genus. Comparative analyses suggest a conservation of the NorA function in staphylococci. We also analyzed the variability of within , for which there are several circulating alleles, differing up to 10% at the nucleotide level, which may hamper proper detection. We demonstrate the applicability of a PCR-based algorithm to detect and differentiate alleles in 52 representing a wider collection of 89 isolates from different hosts. Our results highlight the prevalence of and in different settings and the association of alleles with specific clonal lineages. Ultimately, it confirms the applicability of our PCR-based algorithm to rapidly detect and assign the different alleles, a trait that may impact antimicrobial efflux capacity and the search for potential NorA inhibitors.