Chitosan and cloxacillin combination improve antibiotic efficacy against different lifestyle of coagulase-negative Staphylococcus isolates from chronic bovine mastitis

BRESER, MARÍA L; FELIPE VERÓNICA; BOHL, LUCIANA P; ORELLANO, MARÍA SOLEDAD; ISAAC, PAULA; CONESA, AGUSTÍN; RIVERO, VIRGINIA E; CORREA, SILVIA G; BIANCO, ISMAEL; PORPORATTO, CARINA

Scientific Reports

Nature Publishing Group

Año: 2018

Bovine mastitis affects the health of dairy cows and the profitability of herds worldwide. Coagulasenegativestaphylococci (CNS) are the most frequently isolated pathogens in bovine intramammaryinfection. Based on the wide range of antimicrobial, mucoadhesive and immunostimulant propertiesdemonstrated by chitosan, we have evaluated therapy efficiency of chitosan incorporation to cloxacillinantibiotic as well as its effect against different bacterial lifestyles of seven CNS isolates from chronicintramammary infections. The therapeutic effects of combinations were evaluated on planktoniccultures, bacterial biofilms and intracellular growth in mammary epithelial cells. We found that biofilmsand intracellular growth forms offered a strong protection against antibiotic therapy. On the otherhand, we found that chitosan addition to cloxacillin efficiently reduced the antibiotic concentrationnecessary for bacterial killing in different lifestyle. Remarkably, the combined treatment was not onlyable to inhibit bacterial biofilm establishment and increase preformed biofilm eradication, but it alsoreduced intracellular bacterial viability while it increased IL-6 secretion by infected epithelial cells. Thesefindings provide a new approach to prophylactic drying therapy that could help to improve conventionalantimicrobial treatment against different forms of bacterial growth in an efficient, safer and greenermanner reducing multiresistant bacteria generation and spread.