SAN DIEGO—Invasive methicillin-resistant Staphylococcus aureus (MRSA) infections have declined in incidence among chronic dialysis patients in the United States, according to researchers.

Although the study could not ascertain the reasons for the decrease, investigator Priti Patel, MD, a medical officer with the Centers for Disease Control and Prevention in Atlanta, observed: “It is possible that the Fistula First program and other efforts to reduce central venous catheter use in outpatient hemodialysis centers have contributed to this finding. Efforts occurring within hospitals to reduce bloodstream infections and prevent MRSA transmission also could have played a role in the rate decrease.”

She presented study findings at IDWeek, a joint meeting of the Infectious Diseases Society of America and three other medical organizations.

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The researchers analyzed population-based data from nine U.S. metropolitan areas participating in Active Bacterial Core surveillance (ABCs). During the 2005-2010 study period, the researchers identified 6,462 cases of invasive MRSA among dialysis patients, 85.4% of them outpatient. Incidence rates decreased from 6.5 cases per 100 dialysis patients in 2005 to 4.4 cases per 100 dialysis patients in 2010. The incidence rates decreased annually by 6.5% for outpatients and 10.6% for inpatients, the study found.

The researchers identified 1,971 cases of invasive MRSA in dialysis patients from 2009-2010. Nearly 93% of these cases were bloodstream infections. The median age of these dialysis patients was 59 years (range 3-97 years). The group was 54% male and 57.4% African-American. The dialysis modality was hemodialysis in 97.4% of patients and peritoneal dialysis in 2.6%. The study showed that 70.8% of the patients had been hospitalized in the year prior to the MRSA culture. Among the hemodialysis patients, 60.9% had a central venous catheter.

“The study was conducted to better understand the epidemiology of invasive MRSA infections among dialysis patients, including changes in infection rates over time,” Dr. Patel told Renal & Urology News. “Despite the reassuring finding of decreasing rates between 2005 and 2010, the burden of invasive MRSA infections remains extremely high in dialysis patients compared to other populations. Physician leadership is needed to prevent these devastating infections through improved infection prevention practices.”

For the study, the researchers classified cases as either inpatient (culture collected beyond three days after admission) or outpatient (all others). The researchers calculated the incidence rates using dialysis population denominators from the U.S. Renal Data System.

The mortality rate within seven days of MRSA culture was 6.1%. The investigators concluded that infection prevention measures should include “fastidious vascular access care” and efforts to decrease central venous catheter use.

“Unfortunately, the burden of invasive MRSA infections remains extremely high in the dialysis patient population, and these infections have substantial associated mortality,” Dr. Patel said. “Aggressive prevention efforts are needed that focus on improving hemodialysis catheter care, along with catheter reduction and measures to prevent AV [arteriovenous] fistula-related and graft-related infections. Nephrologists should be aware of the Centers for Disease Control and Prevention’s recommended list of practices for bloodstream infection prevention and the available tools to help put these into practice in dialysis centers.”