Reducing vancomycin use requires a new mind-set
Constraints on prescribing will be difficult
The emergence of vancomycin intermediate-resistant Staphylococcus aureus (VISA) strains spurred by antibiotic pressures raises a critical question: Can the use of vancomycin be sufficiently reduced to preserve its overall efficacy against one of the leading causes of both hospital and community-acquired bacterial infections?
Vancomycin is widely regarded as a last-line antibiotic, particularly against methicillin-resistant S. aureus (MRSA) strains. Clinicians reviewing the limited data available on the first U.S. case of VISA in Michigan, for example, say peritoneal dialysis patients are prone to such infections; the use of vancomycin appears to have been appropriate; and many other patients may be undergoing similar treatment.1 (See related story, p. 150.)
"Vancomycin is the drug that was indicated and would have been used by everybody. This is happening all over the country as we speak," says William Schaffner, MD, professor of infectious diseases and chairman of the department of preventive medicine at the University of Vanderbilt School of Medicine in Nashville, TN.
In addition, attempts to sharply reduce overall use of a drug that may be very effective in an individual patient runs against the time-honored medical mind-set in this country, notes Schaffner.
"It is clear there is a great overuse of antibiotics, but that is very difficult to [change] in a country that values individual decision-making," he says. "You would have to change a whole mind-set. The constraints on prescribing have come slowly and by the hardest [means] in this country. We’re trained to think, What is the best I can do for the patient in front of me?’"
Though similar efforts to eliminate unnecessary vancomycin use followed the emergence of VRE, officials are hopeful the first VISA cases may spur a much greater clinical response.2
"We have put out guidelines and others have commented on this," says David Bell, MD, assistant director for antimicrobial resistance at the CDC national center for infectious diseases. "Sometimes when it is only a theoretical possibility or a problem on the other side of the world, it doesn’t quite sink in as much as when it is in your own backyard. I am optimistic in a way that these [VISA] cases will have a major impact on reducing vancomycin use, whereas previous warnings may not have had as great an impact."
Many MRSA infections, for example, will warrant administration of vancomycin, but the drug is also being commonly used on staph strains that are susceptible to other drugs, he adds.
Indeed, one study found that 44 of 66 identified inappropriate uses of vancomycin were due to empiric treatment without obtaining cultures. The threat of MRSA was frequently cited for the use of vancomycin, but the authors noted that a "a number of antibiotic agents were potentially useful alternatives, but were used rarely."3 The authors also concluded that shortening the course of empiric therapy should decrease the amount of vancomycin used. Such programs targeted at inappropriate use of vancomycin particularly efforts that have buy-in from attending physicians have proven effective at some hospitals. (See Hospital Infection Control, August 1996, pp. 97-101.)
Still, health care settings that are treating a lot of MRSA infections have little choice but to use vancomycin, says Timothy Leach, MD, MPH, chief of infection control at the VA Medical Center, East Orange, NJ.
"Clearly, there are scenarios where you can reduce the amount of vancomycin being used in the hospital, but at an institution like ours where we have a lot of MRSA, we are kind of stuck with using a lot of it," he says. "I don’t think any of us here would be surprised if [VISA] shows up here at the VA in East Orange. I don’t think any hospital would be surprised. There is just a lot of vancomycin being used everywhere."
Some help may be on the way, however. Rhone-Poulenc Rorer in Collegeville, PA, recently filed for approval to begin marketing the drug Synercid, which was effective in lab tests against the first Japanese strain of VISA. (See Hospital Infection Control, July 1997, p. 99.)
The company filed a new drug application with the Food and Drug Administration for the streptogramin antibiotic, which has been administered under a compassionate-use program for VRE patients. Because it is the most likely new weapon to counter the emergence of VISA, the FDA is expected to handle the application quickly and allow distribution of the drug in early 1998. As previously reported in HIC, however, company officials report that despite Synercid’s general overall efficacy, some emerging resistance to the drug has already been observed in both VRE and MRSA.