Genotypic and phenotypic detection of capsular polysaccharide and biofilm formation in Staphylococcus aureus isolated from bovine milk collected from Brazilian dairy farms

SALIMENA, A.P.S.; LANGE, C.C.; CAMUSSONE, C.; SIGNORINI, M.; CALVINHO, L.F.; BRITO, M.A.V.P.; MENDONÇA, L.C.; BORGES, C.A.V.; GUIMARÃES, A.S.; RIBEIRO; J.B.; PICCOLI, R.H.

VETERINARY RESEARCH COMMUNICATIONS

SPRINGER

Lugar: Berlin; Año: 2016 vol. 40 p. 97 - 106

0165-7380

Staphylococcus aureus is a pathogen that frequentlycauses mastitis in bovine herds worldwide. This pathogen producesseveral virulence factors, including cell-associatedadhesins, toxic and cytolytic exoproteins, and capsular polysaccharides.The aim of the present study was to test for the presenceof genes involved in capsular polysaccharide productionand biofilm formation in S. aureus isolated from bovine mastitissamples collected from 119 dairy herds located in threedifferent Brazilian regions, as well as to assay the productionof capsular polysaccharides and biofilm, in vitro. The detectionof the cap, icaAD, and bap genes was performed using PCR.The detection and quantification of capsular polysaccharideproduction was performed using ELISA assays. The ability ofthe isolates to form a biofilm was examined using the polystyrenesurface of microtiter plates. All 159 S. aureus isolatesinvestigated harboured the cap gene: 80 % carried the cap5gene and 20 % carried the cap8 gene. Sixty-nine percent ofthe isolates expressed capsular polysaccharide (CP) in vitro,58 % expressed CP5 and 11 % expressed CP8. All of the isolates harboured the icaA and icaD genes, and 95.6 % ofthe isolates carried the bap gene. Of the 159 isolates analysed,97.5 % were biofilm producers. A significant association betweenthe capsular genotype and phenotype and the amount ofbiofilm formation was detected: cap5/CP5 isolates tended toform more biofilm and to produce a thinner CP layer thancap8/CP8 isolates. The results indicate a high potential forpathogenicity among S. aureus isolated from bovine milk collectedfrom three different regions in Brazil.