Comparing initial and within-host adapted Staphylococcus aureus during the course of a persistent bovine mastitis.

BUZZOLA, FR; GRUNERT, T; MARBACH H; SORDELLI DO; MAYER K; EHLING-SCHULZ, M

Amsterdan, Holanda

Congreso; 29th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID).; 2019

Our work demonstrates that S. aureus within-host adaptation to the bovine mammary gland favores the transition towards a SigB-deficient pathotype associated with a single nucleotide polymorphism in rsbU (G368A → G122D), a contributor to SigB-functionality. Along with phenotypic features, typical for sigB-deficiency, the emergence of the host-adapted isolate implies a selective advantage associated with distinct pathotypic traits, allowing it to presumably better survive extracellular within the mammary gland: strong increased protease activity and production of poly-N-acetylglucosamine (PNAG)-based biofilm. Importantly, the SigB-deficient pathotype also showed a significantly decreased virulence in a mouse model of infection, indicating a switch towards reduced virulence during infection. In conclusion, our work fosters the hypothesis that the sigB-regulon is most crucial for S. aureus adaptation during chronic infection.