Could antibiotic-resistant gene bacteria on cows transfer to create MRSA?

A previously unknown gene in Macrococcus caseolyticus, a harmless bacterium naturally found on the skin of dairy cows, has been found to confer resistance to all beta-lactam antibiotics, including the last generation of cephalosporins used against methicillin-resistant Staphylococcus aureus (MRSA).

The bacterium can spread to milk during milking and has also been found in cheeses and other products made from raw milk.

Now scientists at the Institute of Veterinary Bacteriology of the University of Bern are postulating that this gene could quite conceivably transfer from M. caseolyticus to S. aureus, turning this bacteria into a hazardous MRSA which is known to cause difficult-to-treat infections in hospitals.

Acquired methicillin resistance in bacteria is associated with genes mecA, mecB or mecC. However, none of these genes were present in the M. caseolyticus strains — they carried the novel resistance gene mecD.

The discovery has now been published in the Scientific Reports, a journal of the Nature Publishing Group.