“Superbug” infections more than doubled in hospitals, study finds

November 30, 2007

GAINESVILLE, Fla. — Hospitalizations related to a potentially deadly, antibiotic-resistant “superbug” more than doubled between 1999 and 2005, soaring from 127,000 to nearly 280,000, according to a new study co-authored by a University of Florida researcher.

The study, which appears in the December issue of the journal Emerging Infectious Diseases, is the first to examine the recent magnitude and trends related to methicillin-resistant Staphylococcus aureus, or MRSA, infections. It also found that hospitalizations of patients with general staph infections increased 62 percent across the country.

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

The study concluded that MRSA and staph infections are now “endemic, and in some cases epidemic” in many U.S. hospitals, long-term care facilities and communities.

“We were the first ones to actually look at trends in MRSA and staph hospitalizations,” said David Smith, a UF faculty member who has a dual appointment in zoology and UF’s Emerging Pathogens Institute. “MRSA is out of control. Our numbers suggest that staph and MRSA infections should become a national research and public health priority. ”

The other authors are Ramanan Laxminarayan and Eili Klein, both of Resources for the Future, a Washington D.C.-based nonprofit organization that conducts independent research on environmental, energy, natural resources, and public health issues.

The study found 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,” Laxminarayan said. “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.

“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,” said Dr. J. Glenn Morris Jr., professor and director of the Emerging Pathogens Institute at the University of Florida and an expert on hospital infections. “Research on antibiotic resistance, and on development of therapies to treat antibiotic-resistant infections, should clearly be a national priority.”

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.

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.