Bovine mastitis: control by local use of polyplex nanoparticles

Abstract

Mastitis control presents significant challenges, but the nature of the disease also offers opportunities for intervention. The challenges associated with antimicrobial resistance, biofilm formation and invasive strains inspired us to test the potential use of an organic polymer to kill antimicrobial resistant and intracellular pathogens. PHMB offers a compelling opportunity in the Mastitis area. PHMB has never been applied within the Mastitis area, yet it offers a sim pie "non-antibiotic" way to kill antibiotic resistant and invasive pathogens. We consider that the approach can be developed into an improved teat-dip and (in the longer term) treatment during the "dry off' period". Our approach is to use a non-antibiotic antimicrobial polymer. The main advantage of using an antimicrobial polymer, particularly the one chosen for this study, is that acquired resistance has not been observed. Also, the polymer offers additional advantages, including an ability to kill intracellular bacteria and degrade biofilms. At the very least, an antimicrobial polymer concept is different than the current antibiotic strategies and so worth testing. The main scientific objectives for the pump-prime stage are to: a) Develop an improved non-antibiotic teat-dip formulation using polyplex nanoparticles (PNPs); b) Characterise the in vitro host cell invasion and biofilm formation traits of S. aureus strains isolated from mastitis cases in Brazil; c) Measure the antimicrobial potencies of PNPs against planktonic, biofilm and intracellular S. aureus in vitro; d) Measure PNP adherence to teat surfaces and the speed and duration of antimicrobial action ex vivo. (AU)