Mastitis-related subtypes of bovine Staphylococcus aureus are characterized by different clinical properties

Abstract

Based on a former study from our group, one subtype of Staphylococcus aureus was associated with high within-herd prevalence of mastitis, whereas the other subtypes were associated with a low prevalence (sporadic intramammary infection). To confirm this hypothesis, a prospective study was done in 29 Swiss dairy herds. In particular, milk samples were collected from 10 herds with Staph. aureus herd problems (cases) and compared with samples from 19 herds with only sporadic cases of with Staph. aureus intramammary infection (controls). The isolates were tested for their virulence gene pattern and genotyped by PCR amplification of the 16S-23S rRNA intergenic spacer. The patterns and genotypes were then associated and compared with epidemiological and clinical data. Confirming the hypothesis, one particular subtype (genotype B) was associated with high within-herd and within-cow prevalence of intramammary infection, whereas the other subtypes were associated with low within-herd prevalence and infected single quarters. The gene patterns and genotypes were highly related, demonstrating the genetic diversity of the genotypes. The somatic cell counts were clearly increased in herds with a genotype B problem compared with herds with infections of other genotypes. Based on the different clinical properties and treatment consequences associated with these different genotypes found in Switzerland, we recommend subtyping Staph. aureus in other countries to determine if this finding is universally applicable.

Host adaptation of bovine Staphylococcus aureus seems associated with bacteriological cure after lactational antimicrobial treatment

“…Staphylococcus aureus genotypes can be associated with clinical or epidemiological characteristics such as persistence (Smith et al, 2005a), within-herd prevalence and SCC (Zadoks et al, 2000;Graber et al, 2009), milk production (Middleton and Fox, 2002), and severity of mastitis (Zadoks et al, 2000;Haveri et al, 2007). In our study, quarters with bovine-associated penicillinresistant strains were more likely to have high SCC than quarters with other Staph.…”

“…aureus strains may differ in virulence as evident in clinical signs (Zadoks et al, 2000;Haveri et al, 2007), SCC (Zadoks et al, 2000;Graber et al, 2009), or milk production losses (Middleton and Fox, 2002). The Staph.…”

Bovine Staphylococcus aureus: Subtyping, evolution, and zoonotic transfer

“…In the first instance, 17 different genotypes were found and further characterized for their virulence gene patterns (Fournier et al, 2008). Staphylococcus aureus genotype B (GTB) and GTC were the most frequent genotypes found in bovine milk (80%), but only GTB was contagious, with cow prevalences of up to 87% within herds, whereas GTC showed noncontagious behavior, infecting only single cows in a herd and single quarters of the udder (Fournier et al, 2008;Graber et al, 2009). Staphylococcus aureus GTB is characterized by the presence of the enterotoxin genes sea, sed, and sej and a SNP within the lukE gene (lukEB).…”

“…aureus involved in bovine mastitis (Fournier et al, 2008;Graber et al, 2009). Fournier et al (2008) developed a genotyping method based on amplifying the 16S-23S rRNA intergenic spacer region by PCR (ribosomal spacer-PCR, RS-PCR), which showed the associations of genotype with virulence gene pattern and clinical properties of the disease.…”

Success of interventions in mastitis problems with Staphylococcus aureus after the introduction of an automatic milking system

“…Seven of the eight isolates were positive for the enterotoxin sea, which is a common finding in S. aureus genotype B (GTB) strains (Fournier et al, 2008;Graber et al, 2009). Furthermore, S. aureus isolates belonging to clonal complex 8 and spa type t2953 are a common finding in mastitis milk in Swiss dairy herds as described by Johler et al (2011).…”