Infectious diseases often originate in animals and nature before being transmitted to humans. For example, the origin of the MERS-coronavirus was recently linked to bats and camels.

But these discoveries are much harder to stomach when the animals in question are also a direct source of food for millions of Americans. Unfortunately, that appears to be the case for the MRSA infection.

A newer strain of the MRSA bacteria – an evolved infection that has developed a resistance to antibiotics – has led to an increase in human infections for more than 15 years.

A genome analysis of this strain in several different species revealed a connection between the human sequence and the sequence found in cattle.

"Bovine strains … were closer to the root than the human strains. This led us to conclude that the strains infecting humans originated in cows and that they had evolved from bovine to human host jumps," said study author Ross Fitzgerald of the Roslin Institute and the University of Edinburgh in Scotland, in a press release.

Researchers also discovered that this strain developed new characteristics after human transmission, including antibiotic resistance.

Cattle could be the source of an eventual MRSA pandemic, but further investigation is required, according to researchers. These findings can eventually help stop further MRSA transmission from cattle to humans.

Improving biosecurity and hygiene measures could also prevent the spread of MRSA, and might be responsible for a recent reduction in hospital MRSA infections, the study authors conclude.