Patients harboring methicillin-resistant Staphylococcus aureus (MRSA) for long periods of time continue to be at increased risk of MRSA infection and death, according to a new study in the July 15 issue of Clinical Infectious Diseases, currently available online.
MRSA is an antibiotic-resistant bacterium that can cause a variety of serious infections. The bacterium most commonly colonizes the nostrils, although it can be found in other body sites. Most research has focused on people who are newly colonized by the bacteria and has found that they are at substantial risk of subsequent infections. The new study shows that the increased risk of infection continues, with almost a quarter of MRSA-colonized patients developing infections after a year or more has passed since the colonization was confirmed. The infections include pneumonia and bloodstream events, and some infections were linked to deaths.
"Since infection risk remains substantial among long-term carriers of MRSA, these patients should be targeted for interventions to reduce subsequent risk of infection along with patients who newly acquire MRSA," said author Susan Huang, MD, MPH.
The researchers built on their previous work in this area, which showed that one-third of new MRSA carriers in a large tertiary care medical center developed infections within the year following the first detection of colonization. But, as, Dr. Huang points out, "risks beyond the first year of carriage were largely unknown."
In this study, Dr. Huang and coauthor Rupak Datta, MPH, followed 281 patients who had been MRSA-positive for at least one year and some for more than four years. Of these, 23 percent developed an MRSA infection within the year-long duration of this study. Pneumonia was the most common infection. MRSA was identified as a contributor to the deaths of 14 of the patients.