Genomic Analysis of Staphylococcus aureus Isolates Associated With Peracute Non-gangrenous or Gangrenous Mastitis and Comparison With Other Mastitis-Associated Staphylococcus aureus Isolates

Abstract

Staphylococcus aureus is a highly prevalent cause of mastitis in dairy herds worldwide, capable of causing outcomes that vary from subclinical to peracute gangrenous mastitis. We performed a comparative genomic analysis between 14 isolates of S. aureus, originating from peracute bovine mastitis with very severe signs (9 gangrenous, 5 non-gangrenous) and six isolates originating from subclinical or clinical mastitis with mild to moderate signs, to find differences that could be associated with the clinical outcome of mastitis. Of the 296 virulence factors studied, 219 were detected in all isolates. No difference in the presence of virulence genes was detected between the peracute and control groups. None of the virulence factors were significantly associated with only a single study group. Most of the variation in virulence gene profiles existed between the clonal complexes. Our isolates belonged to five clonal complexes (CC97, CC133, CC151, CC479, and CC522), of which CC522 has previously been detected only in isolates originating from caprine and ovine mastitis, but not from bovine mastitis. For statistical analysis, we sorted the CCs into two groups. The group of CCs including CC133, CC479, and CC522 was associated with gangrenous mastitis, in contrast to the group of CCs including CC97 and CC151. The presence of virulence genes does not explain the clinical outcome of mastitis, but may be affected by allelic variation, and especially different regulation and thus expression in the virulence genes.

Comparative genomics study of Staphylococcus aureus isolated from cattle and humans reveals virulence patterns exclusively associated with bovine clinical mastitis strains

“…Multinomial logistic regression was done with all genes that showed a significant value in Fisher’s test to assess the significance of association between the types of condition, considering raw milk samples as the reference, and the origin of the isolates being the response variable, and the genes, the explanatory variable. Using a modification of the method of Åvall-Jääskeläinen et al (2021) the multinomial logistic regression model was then analyzed by Wald’s Z test and the value of p values were obtained by the pnorm() function of the nnet package. Genes with p < 0.05 were considered significant for the determination of the model in each disease ( Dalgaard, 2008 ).…”

Multiclonal human origin and global expansion of an endemic bacterial pathogen of livestock

“…Numerous studies have employed whole genome sequencing to explore the diversity of S. aureus from dairy cattle but they have tended to include a limited number of isolates from geographically restricted regions (6)(7)(8)(9)(10)(11)(12)(13)(14)(15). In order to address this gap in understanding, we established a genome sequence dataset of 10,254 S. aureus genomes including 1,896 bovine isolates from 32 countries in 6 continents to carry out a comprehensive phylodynamic and accessory genome network analysis.…”

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): antimicrobial‐resistant Staphylococcus aureus in cattle and horses

“…S. aureus is among the most common causes of clinical bovine mastitis as well (Verbeke et al., 2014 ; Åvall‐Jääskeläinen et al., 2021). Occasionally, the severity of clinical S. aureus mastitis can go to peracute gangrenous mastitis causing necrosis of the affected udder quarter, severe systemic signs and even death of the cow (Rainard et al., 2018 ; Åvall‐Jääskeläinen et al., 2021 ).…”

“…SSTI in horses may be treated with a selected number of antimicrobial compounds, including penicillin, ampicillin, oxacillin, ceftiofur, cefquinome, amphenicols, gentamicin, tetracycline, (potentiated) sulfonamides and fluoroquinolones. This is due to the fact that horses are naturally highly sensitive for antimicrobials, with respect to the risk of developing dysbacteriosis (Costa et al, 2015;Arnold et al, 2021). Depending on whether the horses are meant for food production or not, the availability might differ.…”