By Rob Stein
Washington Post Staff Writer
Wednesday, October 17, 2007
A dangerous germ that has been spreading around the country causes more life-threatening infections than public health authorities had thought and is killing more people in the United States each year than the AIDS virus, federal health officials reported yesterday.
The microbe, a strain of a once innocuous staph bacterium that has become invulnerable to first-line antibiotics, is responsible for more than 94,000 serious infections and nearly 19,000 deaths each year, the Centers for Disease Control and Prevention calculated.
Although mounting evidence shows that the infection is becoming more common, the estimate published today in the Journal of the American Medical Association is the first national assessment of the toll from the insidious pathogen, officials said.
"This is a significant public health problem. We should be very worried," said Scott K. Fridkin, a medical epidemiologist at the CDC.
Other researchers noted that the estimate includes only the most serious infections caused by the germ, known as methicillin-resistant Staphylococcus aureus (MRSA).
"It's really just the tip of the iceberg," said Elizabeth A. Bancroft, a medical epidemiologist at the Los Angeles County Department of Public Health who wrote an editorial in JAMA accompanying the new studies. "It is astounding."
MRSA is a strain of the ubiquitous bacterium that usually causes staph infections that are easily treated with common, or first-line, antibiotics in the penicillin family, such as methicillin and amoxicillin. Resistant strains of the organism, however, have been increasingly turning up in hospitals and in small outbreaks outside of heath-care settings, such as among athletes, prison inmates and children.
On Monday, Ashton Bonds, 17, of Lynch Station, Va., succumbed to MRSA, prompting officials to shut down 21 Bedford County schools today for cleaning to prevent further infections. The infection had spread to Bonds's kidneys, liver, lungs and the muscle around his heart.
The MRSA estimate is being published with a report that a strain of another bacterium, which causes ear infections in children, has become impervious to every approved antibiotic for youngsters.
"Taken together, what these two papers show is that we're increasingly facing antibiotic-resistant forms of these very common organisms," Bancroft said.
The reports underscore the need to develop new antibiotics and curb the unnecessary use of those already available, experts said. They should also alert doctors to be on the lookout for antibiotic-resistant infections so patients can be treated with the few remaining effective drugs before they develop serious complications, experts said.
MRSA, which is spread by casual contact, rapidly turns minor abscesses and other skin infections into serious health problems, including painful, disfiguring "necrotizing" abscesses that eat away tissue. The infections can often still be treated by lancing and draining sores and quickly administering other antibiotics, such as bactrim. But in some cases the microbe gets into the lungs, causing unusually serious pneumonia, or spreads into bone, vital organs and the bloodstream, triggering life-threatening complications. Those patients must be hospitalized and given intensive care, including intravenous antibiotics such as vancomycin.
In the new study, Fridkin and his colleagues analyzed data collected in California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New York, Oregon and Tennessee, identifying 5,287 cases of invasive MRSA infection and 988 deaths in 2005. The researchers calculated that MRSA was striking 31.8 out of every 100,000 Americans, which translates to 94,360 cases and 18,650 deaths nationwide. In comparison, complications from the AIDS virus killed about 12,500 Americans in 2005.
"This indicates these life-threatening MRSA infections are much more common than we had thought," Fridkin said.
In fact, the estimate makes MRSA much more common than flesh-eating strep infections, bacterial pneumonia and meningitis combined, Bancroft noted.
"These are some of the most dreaded invasive bacterial diseases out there," she said. "This is clearly a very big deal."
The infection is most common among African Americans and the elderly, but also commonly strikes very young children.
"We see these cases all the time," said Robert S. Daum, a pediatric infectious-disease specialist at the University of Chicago. "In the last five weeks, I've taken care of five children who were sick enough to be hospitalized and require intensive care."
Studies have shown that hospitals could do more to improve standard hygiene to reduce the spread of the infection. Individuals can reduce their risk through common-sense measures, such as frequent hand-washing.
In the second paper, Michael E. Pichichero and Janet R. Casey of the University of Rochester in New York documented the emergence of an antibiotic-resistant strain of another bacterium known as Streptococcus pneumoniae, which causes common ear infections. Although all 11 children identified in the Rochester area with the microbe so far were successfully treated, five required an antibiotic approved only for adults, and one child was left with permanent hearing loss.
The researchers attributed the emergence of the strain to a combination of the overuse of antibiotics and the introduction of a vaccine that protects against the infection.
"The use of the vaccine created an ecological vacuum, and that combined with excessive use of antibiotics to create this new superbug," Pichichero said.