Milk may help bacteria survive antibiotics

DUBLIN, Ireland, Sept. 8 (UPI) -- Portuguese scientists say they've learned milk may help protect potentially dangerous bacteria from being killed by antibiotics used to treat animals.

The researchers from Portugal's Technical University of Lisbon said bacteria sometimes form structures called biofilms that protect them against antibiotics and the body's natural defenses. Now the scientists have discovered one of the most important micro-organisms that causes mastitis in cows and sheep, called staphylococcus, can evade the animal's defenses by forming such biofilms.

Mastitis is an infection of the udder in cattle and sheep.

The researchers, led by Manuela Oliveira of the university's veterinary medicine department, found that when the staphylococci produce a biofilm, that structure protects them against host defenses and antibiotic treatment, allowing the bacteria to persist in the udder.

The researchers said they also determined low concentrations of antibiotics such as penicillin, gentamicin and sulphamethoxazole, combined with trimethoprim, were less effective against staphylococcus when compared with the same experiment performed in the absence of milk.

The research was presented Monday at Dublin, Ireland's Trinity College during the fall meeting of the Society for General Microbiology.