Advancements in the understanding of Staphylococcal mastitis through the use of molecular tools

Staphylococci are the most common organisms isolated from cow’s milk and, depending on species, can have an impact on milk quality and milk yield.  Staphylococci can infect the mammary gland of not only lactating cows, but also heifers prior to parturition.  The objective of this thesis was to improve our understanding of the epidemiology of mastitis caused by staphylococcal species using molecular tools.

In the first study, a draft genome sequence of Staphylococcus chromogenes MU 970, a strain that was isolated from the right rear quarter of a Holstein cow for 16 consecutive months, was completed. Analysis of the genome identified two biofilm-associated protein genes: a gene encoding a putative superantigen-like protein, one gene encoding an IgG binding protein, and an open reading frame (ORF) with 41 per cent homology to a putative coagulase gene of Staphylococcus pseudintermedius. The data provides insight into possible virulence factors associated with chronic S. chromogenes intramammary infections (IMIs). The data also represents the first S. chromogenes genome sequence