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Item Genotypic and phenotypic characterization of Staphylococcus aureus causing persistent and nonpersistent subclinical bovine intramammary infections during lactation or the dry period(Journal of Dairy Science, 2015-01) Klein, R. C.; Veh, K. A.; Ster, C.; Keefe, G.; Lacasse, P.; Scholl, D.; Roy, J. P.; Haine, D.; Dufour, S.; Talbot, v; Ribon, A. O. B.; Malouin, F.Staphylococcus aureus is a significant pathogen frequently causing persistent intramammary infections (IMI) in dairy cows. We compared some genotypic and phenotypic characteristics of 285 strains collected from quarter milk samples from cows with persistent and nonpersistent subclinical IMI across Canada. Variable number of tandem repeats typing was used to infer the persistence of the same S. aureus strain in 3 consecutive quarter milk samples collected at intervals of 3 wk during lactation or before and after dry-off. All first isolates of the series were used as the representative strains from persistent IMI and were compared with nonpersistent strains for the presence of genes seg, sen, sec, and tst as well as by spa typing. Biofilm production in vitro and hld-RNAIII expression levels were also quantified. The gene seg was associated with a reduction in the likelihood of the bacteria to cause a persistent IMI during lactation. Strains persisting through the dry period produced significantly more biofilm in vitro than strains that do not persist after calving. Also, we showed that strains expressing more hld were more likely to be non- persistent during either lactation or through the dry period. Three spa types were predominant (t529, t267, and a novel type: t13401). In the strains studied, the spa type t529 was the most frequent, and 97.0% of the strains of this spa type carried both sen and seg. Strains from the spa type t529 were less likely to cause a persis- tent IMI in the dry period. Most (86.7%) of the strains of the novel spa type (t13401) were negative for seg, sen, or both and produced significantly more biofilm in vitro than t529 and t267. The present study expanded our current knowledge on the genotypic and phenotypic traits of S. aureus strains recovered from persistent and nonpersistent IMI in Canada.Item Draft genome sequences of Staphylococcus aureus strains isolated from subclinical bovine mastitis in Brazil(Genome Announcements, 2016-02-18) Silva, Danielle Mendes; Silva, Mônica Pacheco da; Vidigal, Pedro M. Pereira; Barcelos, Rafael Mazioli; Klein, Raphael Contelli; Aguilar, Ananda Pereira; Fabres-Klein, Mary Hellen; Oliveira, Guilherme; Ribon, Andréa Oliveira BarrosHere, we present the draft genome sequences of four Staphylococcus aureus strains isolated from mastitic milk collected from animals with subclinical manifestations. Three of them were typed as sequence type 126 (ST126), a genotype with no genome sequence available. ST126 is found in several herds of southern Brazil and is described as a bovine pathogen strongly associated with milk around the world.Item An association between milk and slime increases biofilm production by bovine Staphylococcus aureus(Biomed Central Public Veterinary Research, 2015-01-16) Fabres-Klein, Mary Hellen; Santos, Mário Junior Caizer; Klein, Raphael Contelli; Souza, Guilherme Nunes de; Ribon, Andrea de Oliveira BarrosStaphylococcus 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.