Milk helps bacteria survive antibiotics

September 8th, 2008 - 11:44 am ICT by IANS  

London, Sep 8 (IANS) Milk may help protect dangerous bacteria like Staphylococcus from antibiotics used in treating animals.Bacteria sometimes form structures called biofilms that protect them against antibiotics and the body’s natural defences. Micro-oroganisms like Staphylococcus that cause mastitis in cows and sheep can evade the animal’s defences and medicines by forming these protective biofilms.

Mastitis is an infection of the udder in cattle and sheep. It is often a painful condition for the cows and can even cause death.

“Mastitis causes risks for public health if people drink infected milk and is expensive for farmers as it usually causes severe milk production losses, increased treatment costs and means the animals may have to be culled,” said Manuela Oliveira, faculty of veterinary medicine, Technical University of Lisbon, Portugal.

“We have discovered that milk may also protect bacteria against low concentrations of antibiotics - in the presence of milk, three of the five antibiotics tested, penicillin, gentamicin and sulphamethoxazole combined with trimethoprim, were less effective against Staphylococcus when compared with the same experiment performed in the absence of milk,” said Oliveira.

In the past, scientists studying mastitis have conducted most of their experiments under lab conditions rather than mimicking the conditions found in living animals.

This may mean that they have missed important contributory factors. However, Oliveira and her colleagues have used realistic conditions to overcome this problem.

The Lisbon team is currently trying to identify the correct antibiotic concentrations needed to stop formation of biofilms and also the concentrations needed to destroy one that has already formed.

The scientists are also looking at the influence of the forces acting inside an udder during milking to see whether these help or hinder the bacteria in producing biofilms.

“This will allow for a better control of staphylococcal mastitis, cut disease costs and give an important improvement in the protection of consumers’ health,” said Oliveira.

The study was presented Monday at the Society for General Microbiology’s Autumn meeting being held this week at Trinity College, Dublin.

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