title: Molecular characteristics of bap-positive Staphylococcus aureus strains from dairy cow mastitis.
abstract: The biofilm-associated protein (Bap) of Staphylococcus aureus is a high molecular weight cell-wall-anchored protein involved in biofilm formation, first described in bovine mastitis strains from Spain. So far, studies regarding Bap were mainly based on the Spanish strain V329 and its mutants, but no information on the genetic variability of bap-positive Staph. aureus strains is yet available in the literature. The present study investigated the molecular characteristics of 8 bap-positive Staph. aureus strains from subclinical bovine mastitis, isolated in 5 herds; somatic cell counts (SCC) of milk samples were also registered. Strains were characterised using MLST, SPA typing and microarray and the results were compared with V329. All isolates from this study and V329 were assigned to ST126, t605, but some molecular differences were observed. Only herd A and B strains harboured the genes for β-lactams resistance; the leukocidin D/E gene, a type I site-specific deoxyribonuclease subunit, 3rd locus gene and serin-protease A and B were carried by all strains, but not by V329, while serin-protease E was absent in V329 and in another isolate. Four isolates and V329 harboured the fibronectin-binding protein B gene. SCC showed the highest value in the milk sample affected by the only strain carrying all the virulence factors considered. Potential large variability of virulence was evidenced among V329 and all bap-positive Staph. aureus strains considered: the carriage of fnb could enhance the accumulation of biofilm, but the lack of lukD/E and splA, B or E might decrease the invasiveness of strain.
authors: Department of Veterinary Science and Public Health,University of Milan,Via Celoria 10,20133 Milan,Italy.
authors: Gustavo G M
authors: GG
authors: Snel
authors: Alere Technologies GmbH,Jena,Germany.
authors: Stefan
authors: S
authors: Monecke
authors: Alere Technologies GmbH,Jena,Germany.
authors: Ralf
authors: R
authors: Ehricht
authors: Department of Veterinary Science and Public Health,University of Milan,Via Celoria 10,20133 Milan,Italy.
authors: Renata
authors: R
authors: Piccinini
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics; D018441:Biofilms / Q000254:growth & development; D002417:Cattle; D002452:Cell Count; D004269:DNA, Bacterial; D003612:Dairying; D005260:Female; D005838:Genotype; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000166:cytology / Q000382:microbiology; D058885:Multilocus Sequence Typing; D020411:Oligonucleotide Array Sequence Analysis; D013030:Spain; D013203:Staphylococcal Infections / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C425726:Bap protein, Staphylococcus aureus; D004269:DNA, Bacterial
keywords:     bap gene; Staphylococcus aureus; biofilm; dairy cow mastitis