ATLANTA – The overall incidence of methicillin-resistant Staphylococcus aureus infection has been declining in Connecticut since 2007, due entirely to decreases in infections caused by health care–related strains, according to laboratory reports on invasive MRSA isolates from across the state.
From 2001 to 2010, the overall incidence of MRSA infections declined significantly from 26.0 to 22.1 per 100,000 population. The incidence of health care–related MRSA infections declined significantly from 14.4 to 13.8 per 100,000 population, and the incidence of hospital-onset MRSA infections declined significantly from 10.0 to 5.2 per 100,000 population, which together were enough to offset a significant increase in the incidence of community-acquired MRSA infection during the same time period from 1.4 to 3.1 per 100,000 population, Dr. James Hadler reported during a poster session at the International Conference on Emerging Infectious Diseases.
Courtesy Janice Haney Carr/CDC
Recent research shows that the overall incidence of methicillin-resistant (MRSA) infection has been declining in the state of Connecticut.
The improvements in the health care–related strains of MRSA coincided with increased public, public health, and hospital attention to the problem of MRSA infections, said Dr. Hadler of the Connecticut and Yale Emerging Infections Program, Yale School of Public Health, New Haven, Conn.
MRSA has posed two distinct problems over the years, including hospital-onset bloodstream infections associated with highly-resistant strains, and community-onset infections, which mostly involve skin and soft-tissue infections caused by less resistant community MRSA strains. These started to increase in the 1980s and 1990s, respectively. Now hospital strains are causing infection in the community, and community strains are causing infections in the hospital, Dr. Hadler said.
Laboratory reporting for invasive MRSA became mandatory in Connecticut in 2001, and legislative initiatives in Connecticut in 2006 resulted in laws requiring reporting of hospital-related infection. In 2007, national attention was called to MRSA in a publication by the Emerging Infections Program that highlighted the magnitude of the problem, and the passing of legislation in Connecticut and other states mandating reporting of hospital infections.
From 2001 to 2007, the incidence of MRSA in Connecticut was either increasing or stable, but after 2007 the incidence began to decline, he explained.
Furthermore, an examination of incidence trends in three time periods (2001-2003, 2004-2006, and 2007-2010) showed that the trends for decline did indeed occur only from 2007 to 2010 for the overall, health care–associated, and hospital-onset cases. The increase in community-acquired disease occurred from 2004 to 2006.
Between 2007 and 2010, the overall incidence decreased 18.8%, the hospital-onset incidence decreased by 33.2%, and health care–associated infections decreased by 12.8%. After the initial increase from 2004 to 2006, the incidence of community-acquired cases decreased by 12.7%.
MRSA cases in this study were defined as those with MRSA isolated from normally sterile body sites. Cases were classified, based on a medical record review, as being a hospital-onset case (with MRSA isolated greater than 2 days after admission), a community-onset case, or a health care–associated case (with MRSA acquired during hospitalization, surgery, dialysis, or a stay in a long-term care facility in the past year, or central line at diagnosis).
The findings are encouraging, although continued monitoring to assess the sustainability of these apparent improvements in MRSA prevention is needed, according to Dr. Hadler.
"It looks like we’re making real progress with MRSA-related hospital- and health care–associated infections, but bigger improvements have been dampened by the community MRSA strains," he said in an interview.
The findings in Connecticut may reflect those of other areas in the United States, because Connecticut, which serves as one of seven MRSA surveillance areas that are part of the Centers for Disease Control and Prevention’s Emerging Infections Programs, is demographically diverse and representative of the larger U.S. population, he added.
Dr. Hadler said he had no relevant financial disclosures.