New CDC report, recent events add to MRSA's infamy

Four student deaths occurred in recent weeks in locations across the country: a preschooler in Salisbury, N.H.; an 11-year-old in Vancleave, Miss.; a 12-year-old in Brooklyn, N.Y.; and a 17-year-old in Bedford, Va. More could follow.

These young people had a very serious problem in common: methicillin-resistant Staphylococcus aureus.

With headlines recounting these deaths and detailing an Oct. 17 Journal of the American Medical Association article on MRSA incidence rates, a firestorm of activity ensued. The JAMA article, a Centers for Disease Control and Prevention report, offered the first U.S. nationwide estimates of the burden of invasive MRSA disease based on 2005 data. An accompanying editorial noted that if these projections were accurate, the MRSA death rate would exceed the mortality totals attributable to HIV/AIDS for that year.

At the same time, cases of the antibiotic-resistant bacteria were noted in schools around the nation, with many closing their doors to scrub down their facilities. Following a student protest in the Virginia school district attended by the 17-year-old, for instance, officials closed all 21 schools for cleaning.

According to the CDC report, though, mortality from MRSA in the community is actually rare. The majority of deaths related to the infection are attributed to strains associated with health care.

Still, that finding did not quiet concerns, which some see as positive because it brought the reality of this infection to the mainstream. "We've known for some years when treating skin infections thought to be caused by staph, physicians should consider MRSA," said John J. Jernigan MD, a medical epidemiologist at the CDC.

The CDC MRSA report studied the U.S. incidence and mortality rates for 2005. Researchers estimate 94,360 invasive MRSA infections occurred that year, with 18,650 cases resulting in death. This total case number is nearly triple a CDC 2001 estimate of 31,440.

"The study was the first population-based look at severe MRSA disease," Dr. Jernigan said. "It showed that an overwhelming majority are health care-associated. The major message is hospitals and health care facilities need to make MRSA prevention a priority."

While topics such as MRSA and other resistant organisms are not new for public health officials, the issue has become more prominent in physician offices. And this new public awareness underscores to both physicians and patients the importance of appropriate antibiotic use.

"We've been using antibiotics inappropriately for years," said Bruce W. Dixon, MD, director of the Allegheny County Health Dept. in Pittsburgh. "That's absolutely the reason we have these growing numbers of strains that are antibiotic resistant. It is a society that wants a pill for everything, and it puts doctors in a difficult position. If the patient doesn't get it from one doctor, they'll go to another."

Steps toward prevention

In the Pittsburgh area, where last month nine football players in one school had confirmed MRSA infections and several more cases were reported in others, parents took children with suspicious lesions to doctors and insisted on MRSA cultures.

"There is still a group of doctors who don't culture in the interest of costs," Dr. Dixon said. "If you have the ability to culture, go ahead. It's assuring to know if it is or it is not. If it is, you can observe the patient more carefully to make sure it is healing. If you can't culture and see any abscess, use an antibiotic that will take care of MRSA."

The best prevention, public health officials say, is simple hygiene. "We are the carriers of the organism. Humans can have a personal reservoir of this," said Edward J. Septimus, MD, director of clinical integration at the Methodist Hospital System in Houston. He is also a member of the board of directors of the Infectious Diseases Society of America. "The best prevention protocol is hand washing. Not sharing razor blades; wiping down equipment; or covering a cut or a break in the skin will all cut down on transmission."

Nonetheless, closing schools to disinfect is generally not necessary, according to the CDC. "It's inappropriate. It costs a lot to close a school," Dr. Dixon said. "MRSA is spread person to person and, while it might be good public relations, it is not good public health."

According to the CDC, about 85% of all invasive MRSA infections were associated with health care settings. Of those, about two-thirds occurred outside of the hospital, while about one-third occurred during hospitalization. About 14% of all the infections occurred in people without obvious exposures to health care.

Health care-associated and community-associated MRSA have different clinical and molecular epidemiology. "The hospital-associated are 'USA 100 strains' and most community strains are 'USA 300,' but we're starting to see a mix," Dr. Septimus said. "We're seeing 'USA 300' in the hospital and 'USA 100' in the community. The boundaries are beginning to blur."

MRSA is part of the bigger problem of bad bugs, accounting for only about 10% of health care-associated infections. "If we were to eliminate it, we'd still have so many more," Dr. Jernigan said. "MRSA is important, but we need to take a comprehensive approach to have an impact on other resistant pathogens, such as C-difficile."

Neil Fishman, MD, associate professor of infectious diseases at the University of Pennsylvania, talked about the gram-negative organisms resistant to all antibiotics. He mentioned Acinetobacter, which has been found in soldiers returning from Iraq; and the more common, Klebsiella. "It's a different world versus even five years ago," said Dr. Fishman, who chairs the IDSA's Antimicrobial Resistance Work Group. "Multidrug-resistant bugs like Klebsiella and MRSA have cropped up and spread practically before anyone has had the chance to examine them under the microscope, much less do anything to stop their spread. If this continues, we will return to the pre-antibiotic era."