Health officials are concerned about the bacterium Staphylococcus aureus, or golden staph, which is the most common cause of staphylococcal infections among people. The same genetic strains of Staphylococcus aureus have been found among both human and animal cases.
Shelley Rankin, a microbiologist at the Ryan Veterinary Hospital of the University of Pennsylvania, said she suspected that the frequency of the transfer of the disease between pets and humans was extremely low, and suggested a figure far less than 1 per cent.
Yesterday, Dr Rankin reported on Staphylococcus aureus isolated from 38 animal cases at her hospital from 2002 to 2005. She said six of the cases "almost certainly were infected" at her hospital, the world’s largest veterinary hospital. An additional 12 cases might have been infected there, she said.
After Staphylococcus aureus among humans developed resistance to penicillin many years ago, doctors prescribed another antibiotic, methicillin. Now methicillin-resistant staphylococcal infections lead to more than 125,000 hospitalisations a year in the US, epidemiologists have reported.
The bacteria can cause the same variety of problems in animals and humans, including skin infections, abscesses, joint infections and death.
"The question on everyone’s lips is: Where is it coming from?" Dr Rankin said. "Probably it is not an owner patting Fluffy on the head."
Staphylococci are commonly found on human skin and in the nasal passages, but much less so on animal skin, Dr Rankin said. Veterinarians have reported cases among dogs after they underwent a limb amputation and other kinds of surgery.