Rare staph infection reported in Phila.

A patient at Pennsylvania Hospital has a rare form of staph infection that is believed to stem from the overuse of antibiotics.

The patient - a woman on kidney dialysis - had been transferred from Delaware and did not catch the bacterial infection at the University of Pennsylvania-owned hospital, Penn officials said.

Experts say the rare case of so-called vancomycin-resistant Staphylococcus aureus or VRSA underscores the importance of surveillance and frequent hand-washing in hospitals to prevent the spread of such infections. It also shows the perils of overusing potent antibiotics such as vancomycin, which doctors often use when other medications fail.

VRSA, as its name implies, is able to survive the onslaught of vancomycin.

The drug is commonly used to keep patients with weak or no kidney function from getting bacterial infections.

While rare - 11 cases have been reported nationally - the infection is not particularly virulent and is susceptible to existing antibiotics, said Neil Fishman, an infectious-disease expert at Penn.

VRSA has never been transmitted from one person to another, he said. Rather, the resistant form appears to develop in a patient with two infections: the more common MRSA (methicillin-resistant Staphylococcus aureus) and drug-resistant bacteria known as vancomycin-resistant Enterococcus or VRE.

"Vancomycin-resistance genes from the VRE are transferred to the MRSA, and that leads to the VRSA," Fishman said.

Because the patient was known to have MRSA when she was admitted to Pennsylvania Hospital, she has been in contact isolation since her arrival. Contact isolation was increased so that everyone who enters her room is logged in as extra protection against transmission.

"As a precaution, we are testing the limited number of staff who have been in regular contact with the patient," Penn said in a statement.

The health system also noted that the patient had several severe medical problems.

The case "underscores the need for monitoring of antibiotic use and the importance of infectious-control protocols such as hand-washing to limit the spread of not only this organization but other multidrug-resistant organisms," said infectious-disease doctor Deena Athas of Thomas Jefferson University.

Athas said the precautions taken with patients infected with this form of staph might be "one reason VRSA may not have spread widely" or been transmitted from one person to another.

Athas and Fishman agreed that the case illustrated the danger of overusing antibiotics.

"It is a consequence of overexposure to vancomycin," Fishman said. First sold by Eli Lilly in the 1950s, the drug is licensed in the United States to ViroPharma Inc., based in Exton.

According to the latest data from the U.S. Centers for Disease Control and Prevention, this would be the first reported case of VRSA in the country since 2007, when two cases were reported.

Four other cases were reported in 2006 and 2005. A less-resistant form of the bacteria, vancomycin-intermediate staph, is more common, with 13 cases this year and 183 reported to the CDC from 2005 through 2009.

The case at Pennsylvania Hospital is being investigated by infectious-disease experts at Penn in conjunction with the Pennsylvania Department of Health and the CDC.