Third case of VRSA rocks SHEA meeting

VRSA continuing to emerge, or is it already here?

A third case of vancomycin-resistant Staphylo-coccus aureus (VRSA) has occurred in the United States, opening up the distinct possibility that the much-feared superbug will continue to emerge.

Though little was known about the case as this issue went to press, Hospital Infection Control was able to confirm that it occurred in a patient in New York.

Last year, cases were confirmed in Pennsylvania and Michigan.1,2

The mechanism of resistance in both cases last year was the result of a "conjugation event": a genetic transfer from vancomycin-resistant enterococci to MRSA. The vancomycin-resistance determinant vanA, typically found in VRE but never in a clinical staph strain, was found in the VRSA isolates in both cases. Researchers in England proved such a genetic transfer could occur a decade ago in controversial laboratory studies that produced a fully resistant strain in vitro.3

The mechanism of resistance on the most recent case could not be determined as this story was filed, but the report of a third case of VRSA in United States was first announced recently in Philadelphia at the annual conference of the Society for Healthcare Epidemiology of America (SHEA).

A bad outcome

"The more antibiotic resistant a microbe is, the more likely a patient, on average, will receive the wrong drug first," says Barry Farr, MD, epidemiologist at the University of Virginia in Charlottesville.

"That is associated with prolongation of the hospital illness, [length of] stay, increased costs and, for serious infections, an increase in mortality. In any pathogen, increasing antibiotic resistance has been associated with bad outcomes for patients," he adds.

Moreover, laboratory experts warn that the approaches used in many clinical labs may not be sufficient to detect VRSA, suggesting that VRSA has already multiplied beyond the sporadic identified case but is going undetected.

"This is just one more showing up," Farr notes in between sessions at the SHEA meeting. "We’ve expected to see these in that last decade ever since studies showed you could put MRSA and VRE together in a test tube or on a rabbit and end up with VRSA."

The Centers for Disease Control and Prevention (CDC) recommends contact precautions when caring for patients with VRSA infections. That includes placing the patient in a private room, wearing gloves and a gown during patient contact, washing hands after contact with the patient and infectious body tissues or fluids, and not sharing patient-care items with other patients.

For guidelines on preventing spread of VRSA, go to www.cdc.gov/ncidod/hip/10_20.pdf. Isolation of S. aureus with confirmed or "presumptive" vancomycin resistance should be saved and reported via state and local health departments to CDC’s Division of Healthcare Quality Promotion, National Center for Infectious Diseases at (800) 893-0485.

References

1. Centers for Disease Control and Prevention. Public health dispatch: Vancomycin-resistant Staphylococcus aureus — Pennsylvania, 2002. MMWR 2002; 51:902.

2. Centers for Disease Control and Prevention. Staphylo-coccus aureus resistant to vancomycin, United States, 2002. MMWR 2002; 51:565-567.

3. Noble WC, Virani Z, Cree RG. Co-transfer of vancomycin and other resistance genes from Enterococcus faecalis NCTC 12201 to Staphylococcus aureus. FEMS Microbiol Lett 1992; 93:195-198.