An association between milk and slime increases biofilm production by bovine Staphylococcus aureus

Abstract

BackgroundStaphylococcus aureus is associated with chronic mastitis in cattle, and disease manifestation is usually refractory to antibiotic therapy. Biofilm production is a key element of S. aureus pathogenesis and may contribute to the treatment failure that is consistently reported by veterinarians. Minas Gerais State is the largest milk-producing state in Brazil, and the characterization of bacterial isolates is an important aspect of disease control for dairy farmers. Here, we investigated the potential of S. aureus isolated from bovine mastitis to produce slime and biofilm in a skim-milk medium and classified the isolates according to their agr type.ResultsSlime was detected using the Congo Red agar (CRA) test in 35.18% (19/54) of the strains; however, 87.04% (47/54) of the strains were considered biofilm-positive based on crystal violet staining. Compared to TSB supplemented with 0.25% glucose, skim milk significantly increased the production of biofilm, but this effect was only observed in slime-producing strains. The bacteria belonged to agr groups I (12/54), II (34/54), III (6/54), and IV (2/54), and bacteria in agr group III were found to be stronger biofilm producers than those in groups I and II. Again, milk had a significant influence only on slime-positive agr I and II isolates, revealing an association between milk and slime.ConclusionsThe present study demonstrated that skim-milk medium and slime production are two factors that together influence biofilm formation by bovine strains of S. aureus. A predominance of bacteria belonging to agr group II was observed, and bacteria from agr group III showed the highest proportion of biofilm producers. The majority of bacteria characterized in this study formed biofilm in milk, which suggests that biofilm formation has an important role in the virulence of S. aureus isolated from bovine intramammary infections.

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

“…In these studies and in our study, the percentage of biofilm producing isolates was high, ranging from 97 % to 100 % positivity. The percentage of biofilm producing isolates in our study was, however, higher than those reported by Vasudevan et al (2003); Fox et al (2005) Marques et al (2013), andFabres-Klein et al (2015) found that 80 %, 81 % and 87 % of isolates produced biofilms, respectively.…”

“…Studies conducted with S. aureus isolated from bovine mastitis in different countries reported the concomitant presence of both genes in most of the S. aureus isolates analysed (Vasudevan et al 2003;Cucarella et al 2004;Szweda et al 2012;Melo et al 2013;Prenafeta et al 2014;Bar-Gal et al 2015;Castelani et al 2015;Fabres-Klein et al 2015). Moreover, other studies (Ciftci et al 2009;Dhanawade et al 2010;Coelho et al 2011;Darwish and Asfour 2013;Marques et al 2013) reported that lower percentages of S. aureus of bovine origin harboured these genes.…”

“…Xue et al (2014) reported that milk and lactose increased biofilm formation in two bovine mastitis S. aureus isolates. Fabres-Klein et al (2015) demonstrated that milk and slime production are factors that have a positive effect on biofilm production by bovine S. aureus. In addition, they suggested that bovine isolates of S. aureus adapt to the milieu found in the udder, with milk influencing biofilm production and consequently promoting bacterial survival.…”

Estudo genotípico e fenotípico de <i>Staphylococcus</i> spp formadores de biofilme isolados em linhas de produção de queijo Minas Frescal e de leite de vacas com mastite no Estado de São Paulo, Brasil

“…Um biofilme maduro contém estruturas tridimensionais específicas, referidas como torres ou cogumelos, separados por canais cheios de líquido (ATSHAN et al, 2012;CUE et al, 2012 O primeiro relato de biofilme foi feito há mais de 70 anos (ZOBELL,1943), e ainda é uma preocupação na área das industrias, especificamente de alimentos, ambientais e biomédicas (FLINT et al, 1997;SIHORKAR;VYAS, 2001;MAUKONEN et al, 2003;VÁZQUEZ-SÁNCHEZ et al, 2013).…”

“…É de extrema importância higienizar os equipamentos de processamento considerando-se tanto a composição inorgânica dos depósitos como a microflora constitutiva. A formação de biofilmes em industrias de produtos lácteos é predominantemente por substâncias bacterianas poliméricas extracelulares (EPS) nos resíduos de leite (FLINT et al, 1997;MITTELMAN, 1998 …”