Staphylococcus aureus within-host adaptation in persistent bovine intramammary infections

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

Simposio; 18th International Symposium on Staphylococci and Staphylococcal Infections; 2018

Bovine mastitis due to Staphylococcus aureus is a major problem in the dairy industry. Recurrentbovine intramammary infections (IMIs) are very common, presenting the farmer with concernsfor the animal well-being, food safety and economic loss. Earlier studies of persistent bovine IMIsrecognize the existence of only a single or a few S. aureus clone(s) in a herd, which is thought to bea result of S. aureus adaptation to the individual udder environment.Here we aim to shed light onto the S. aureus within-host adaptation over the course of a persistentbovine IMI. Analysing an initial and a host adapted S. aureus isolate, sampled over the courseof three months from a naturally infected dairy cow with no antibiotic treatment, enabled us tocapture their essential phenotypic differences, including capsule polysaccharide expression andproteolytic activity. Since intracellular survival of the pathogen in non-professional phagocytes isexpected to be one key factor in chronic S. aureus infections, we assessed their internalization andsurvival potential with bovine mammary epithelial cells (Mac-T), their binding to fibronectin, anddifferences in their cytotoxic profile affecting the health of Mac-T cells, all revealing a preliminarydistinguishable profile of the initial and within-host adapted S. aureus strain.The precise molecular mechanisms of this particular S. aureus? within-host adapted lifestyle willhave to be further investigated to allow pheno- and genotypic differentiation, paving the way tounderstand the role of S. aureus ? host cell interaction in the pathogenesis of bovine mastitis.