New antibiotic resistance gene found in milk.

New antibiotic resistance gene found in milk according to a new study by researchers in the University of Bern. A new antibiotic resistance gene has been found in bacteria from dairy cows. This gene confers resistance to all beta-lactam antibiotics including the last generation of cephalosporins used against methicillin-resistant Staphylococcus aureus. A transfer to S. aureus which is likely according to the researchers would jeopardize the use of reserve antibiotics to treat human infections caused by multidrug-resistant bacteria in hospitals. Researchers of the Institute of Veterinary Bacteriology of the University of Bern have identified a new methicillin resistance gene in strains of M. caseolyticus isolated from milk. Macrococcus caseolyticus is a harmless bacterium naturally found on the skin of dairy cows which can spread to milk during the milking process. It can also be present in dairy products made from raw milk like e.g. cheese. The transfer of the gene to Staphylococcus aureus, a bacteria found on the skin and mucosa of animals and humans, would have dramatic consequences for public health as experimental investigations of the "resistance island" showed that it also has the potential for integration into the chromosome of S. aureus. It is not impossible that this may happen in nature, since S. aureus and M. caseolyticus share the same habitats. This methicillin resistance gene would turn this bacteria into a hazardous methicillin-resistant S. aureus (MRSA), which is known to cause difficult-to-treat infections in hospitals. M. caseolyticus containing the novel mecD gene has been so far mainly found in cattle but in one case it has been isolated from skin infection in a dog indicating that this bacteria has the potential to colonize different animal species.