Molecular characteristics of bap-positiveStaphylococcus aureusstrains 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.

Virulence Genes of S. aureus from Dairy Cow Mastitis and Contagiousness Risk

“…This represents a cow-associated lineage that has been found in the Americas and in Southern Europe (see MLST database) [22], while studies from Central and Northern Europe failed to detect it [20,21,22,23]. Isolates of this lineage were observed in LP, but also in MHP and HP herds.…”

“…Sed , ser , and sej belong to a cluster harbored by different CCs, out of them CC151 and CC479 were indicated as the most frequent ones [11]. The genes sea , sak and scn , which are carried by β-hemolysin-converting bacteriophages, were present uniquely in some CC8 strains; their prevalence was higher than in other studies on bovine isolates, although lower than in studies on isolates from humans [20,21,22,23,24,25,26,27]. Accordingly, a recent paper reported that CC8 strains of bovine or human origin differed for the mobile genetic elements, among them the β-hemolysin-converting prophages: all bovine-only isolates were devoid of such prophages [28], probably because the untruncated hlb is necessary in ungulates for the different structure of erythrocyte membranes.…”

Staphylococcus aureusBiofilm Removal by Targeting Biofilm-Associated Extracellular Proteins

“…Among various surface proteins, biofilm-associated-protein (Bap) was first reported as a large, multi-domain, cell surface anchored protein, which plays a crucial role in S. aureus biofilm development, architecture and in the pathogenesis of bovine mastitis [15][16][17][18][19] . A recent study carried out in Brazil showed the presence of bap gene in all the coagulase-negative Staphylococcus spp.…”

Staphylococcus aureus biofilm removal by targeting biofilm-associated extracellular proteins

“…There are several reports on the role of surface proteins in S. aureus biofilm formation and its stability 8 9 . Among various surface proteins, biofilm-associated protein (Bap) was first reported as a large, multi-domain, cell surface-anchored protein, which plays a crucial role in S. aureus biofilm development, architecture and in the pathogenesis of bovine mastitis 10 11 12 13 . A study carried out in Brazil showed the presence of bap gene in all the coagulase-negative Staphylococcus spp.…”