New Study: Hospitalizations Related to Superbug Infections Double over Six Years

WASHINGTON - Hospitalizations related to methicillin-resistant Staphylococcus aureus (MRSA) infections more than doubled, from 127,000 to nearly 280,000, between 1999 and 2005, according to a new study in the December issue of the journal Emerging Infectious Diseases. During that same period, hospitalizations of patients with general staph infections increased 62 percent across the country.

Staph, or Staphylococcus aureus, are a kind of bacteria that attack wounds and cause life-threatening infections, such as blood poisoning and pneumonia. Methicillin-resistant S. aureus (MRSA) are "superbugs" that have evolved resistance to most commonly used antibiotics, so they are more difficult and expensive to treat.

The study, which is the first to examine the recent magnitude and trends related to staph and MRSA infections, found that such infections are now "endemic, and in some cases epidemic," in many U.S. hospitals, long-term care facilities, and communities. Study researchers say that control of the infection should be made a "national priority."

The study, conducted by researchers at Resources for the Future and the University of Florida, finds that the pattern of infection is changing. The researchers saw dramatic increases in the rate of minor skin and soft tissue infections caused by staph and MRSA that are commonly spread outside hospital walls. At the same time, there was no trend in the number of deaths from hospital-associated staph or MRSA infections.

"Taken together, these findings indicate a change in the ecology of the disease," says senior study author Ramanan Laxminarayan, Ph.D., M.P.H., of Extending the Cure, a project of Resources for the Future. "Antibiotic-resistant infections are spreading more rapidly in the community while the epidemic of drug-resistant infections in hospitals continues unabated.

In all likelihood, the researchers say, MRSA infections are spreading in both hospitals and communities, complicating efforts to prevent infections in hospital patients. Hospital-acquired infections from all causes result in an estimated 90,000 deaths per year, and are the sixth-leading cause of death nationally. They also increase patient suffering and the length of time patients spend in the hospital in addition to direct health care costs, estimated to be more than $6 billion annually.

Antibiotic-resistant infections impose even greater costs. Several studies have estimated that antibiotic resistant infections increase direct costs by 30 percent to 100 percent. MRSA-specific studies suggest that the additional cost of treating an antibiotic-resistant staph infection versus an antibiotic-sensitive infection range from a minimum of $3,000 to more than $35,000 per case. This suggests that such infections cost the health care system an extra $830 million to $9.7 billion in 2005, even without taking into account indirect costs related to patient pain, illness, and time spent in the hospital.

"At a national level, the rising tide of antibiotic resistance that we are seeing raises concerns about our ability to effectively treat serious bacterial infections," says J. Glenn Morris, Jr., M.D., professor and director of the Emerging Pathogens Institute at the University of Florida and a renowned expert on hospital infections. "Research on antibiotic resistance, and on development of therapies to treat antibiotic-resistant infections, should clearly be a national priority."

In addition, the researchers say that the rising incidence of MRSA will likely increase demand for vancomycin, a powerful antibiotic often used when other antibiotics fail. The emergence of infections that are resistant to vancomycin is already a serious problem in hospitals, the researchers contend. The MRSA epidemic is likely to make things worse.

The researchers offer several suggestions to address the spread of both staph and MRSA infections. These include national surveillance or reporting requirements for these infections, more research to explore the interaction between community- and hospital-associated infection, stepped-up efforts to control hospital infection, and increased investment in the development of a staph vaccine.

Funding for this research was provided by the Robert Wood Johnson Foundation's Pioneer Portfolio, which supports innovative ideas that may lead to breakthroughs in the future of health and health care.

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