Characterization of genetic diversity and population structure within Staphylococcus chromogenes by multilocus sequence typing

Staphylococcus chromogenes is a common skin commensal in cattle and has been identified as frequent cause of bovine mastitis intramammary infections. We have developed seven locus Multilocus Sequence Typing (MLST) scheme for typing S . Sequence-based systems, such MLST, application studies genetic diversity, population structure, epidemiology, including strain variation factor pathogenicity or host adaptation. The was tested on 120 isolates collected from three geographic locations, Vermont Washington State the United States Belgium. A total 46 sequence types (STs) were with most STs being location specific. utility indicated by discrimination power 95.6% all greater than 90% each locations. Phylogenetic analysis placed 39 into single core group consistent lineage; this differ less 0.5% at nucleotide level. Most diversification lineage can be attributed to mutation; recombination plays limited role. This includes two clusters variants starburst configurations indicative recent clonal expansion; nearly 50% sampled study are these clusters. remaining set apart having alleles highly variable sequences one more loci. Recombination had higher impact mutation outlier STs. Alleles hypervariable detected five loci used MLST scheme; average distances between ranged 12 34 nucleotides. extent differences suggests may remnants an ancestral genotype.