SAN DIEGO — Two medical centers of similar size located in the northeastern United States that use different methicillin-resistant Staphylococcus aureus infection control strategies have very similar rates of hospital-onset MRSA infection, results from a year-long analysis showed.
“Our study illustrates the need for these kinds of comparisons so we can decide which MRSA infection control strategies work best,” lead investigator Dr. Kathryn B. Kirkland said at the annual meeting of the Society for Healthcare Epidemiology of America. “We need to expand the set of measures that we have that will allow us to do ongoing comparisons across a range of settings. We also need to have better national benchmarks.”
Researchers set out to compare the incidence of MRSA and other health care-acquired infections at Dartmouth-Hitchcock Medical Center, Lebanon, N.H., and Fletcher Allen Health Care, Burlington, Vt., between October 2007 and September 2008. Both are academic medical centers, with an average daily census of 295 and 387, respectively, said Dr. Kirkland, medical director of infection prevention at Dartmouth-Hitchcock Medical Center.
Fletcher Allen Health Care staff screen for MRSA upon admission and screen all ICU patients on a weekly basis; the staff also uses contact precautions when providing care for any inpatient known to be colonized or infected with MRSA. In contrast, although Dartmouth-Hitchcock staff maintain an aggressive hand hygiene protocol, they do not screen for MRSA and use contact precautions only for patients with open wounds, uncontrolled secretions, or diarrhea, regardless of causative organism.
The researchers used National Healthcare Safety Network definitions to track hospital-onset primary bloodstream infections and MRSA infections, as well as Clostridium difficile infections with onset during or within 30 days of hospitalization. They calculated rates as per 1,000 patient days and used direct observation to estimate hand hygiene compliance.
During the study period, the number of inpatient days at Dartmouth-Hitchcock Medical Center and Fletcher Allen Health Care were 114,828 and 126,600, respectively, while the estimated hand hygiene compliance was 84% and 93%.
Dartmouth-Hitchcock and Fletcher Allen did not differ significantly in the rate of new hospital-onset infections (0.48 vs. 0.54 per 1,000 patient days, respectively), the rate of primary MRSA bloodstream infections (0.06 vs. 0.08 per 1,000 patient days), the rate of primary methicillin-sensitive S. aureus bloodstream infections (0.1 vs. 0.07 per 1,000 patient days), or the rate of primary bloodstream infections due to non-S. aureus organisms (0.49 vs. 0.52 per 1,000 patient days).
The only significant difference between the two medical centers was in the rate of C. difficile infection, which was higher at Fletcher Allen Health Care (0.81 vs. 0.55 patient days).
“Both programs could be said to successfully control health care-associated infections, including invasive MRSA, primary bloodstream infections due to all pathogens, and C. difficile infection,” Dr. Kirkland concluded. “Both strategies are effective in controlling a range of health care-associated infections. It may be that the hand hygiene rates, which were high at both institutions, are the key to the low observed rates that we saw. Contributors to the difference in the rates of C. difficile infection are unexplained, as our control programs differ in almost every aspect.”
Dr. Kirkland had no conflicts of interest to disclose.