Hospitalizations associated with a drug-resistant form of a Staphylococcus bacterium doubled over six years in the U.S. to nearly 280,000 cases in 2005, according to a study published Thursday that provides a wider picture of the bug’s effects.
The rise in illnesses from methicillin-resistant Staphylococcus aureus, also known as MRSA, stemmed mostly from increased skin and soft-tissue infections, which typically are associated with strains acquired outside hospitals, the study found.
The figures provide the first good look at national trends over time, said Dr. Elizabeth Bancroft, a medical epidemiologist at the Los Angeles County Department of Public Health who was not involved in the study.
“It gives us more evidence that this bug has been here for a while and has been steadily growing,” she said.
Based on the data collected, the study estimated there were about 127,000 hospitalizations associated with MRSA in 1999 and about 278,000 in 2005.
Researchers found that the number of blood-poisoning and pneumonia cases associated with MRSA increased modestly, while the number of infections in other forms such as skin infections nearly tripled. The death toll rose from 4,700 in 1999 to about 6,600 in 2005, according to the study.
The report, published in the journal Emerging Infectious Diseases, was somewhat at odds with a study in October that focused on the most serious kinds of MRSA infections, such as blood and lung-fluid infections, using data from nine U.S. metropolitan areas, including Denver. It estimated that 94,000 Americans suffered invasive MRSA infections in 2005 and that about 19,000 died.
Senior author Ramanan Laxminarayan, an epidemiologist with the nonprofit research group Resources for the Future, attributed the differences to methodology and question answering.
The dominance of skin infections in the new analysis provides a nugget of good news, said Dr. Scott Fridkin, a researcher at the U.S. Centers for Disease Control and Prevention who worked on October’s study. “Skin infections don’t tend to be life-threatening,” he said.
