PROVIDENCE – A new study led by a Rhode Island Hospital researcher has identified several populations as particularly vulnerable to methicillin-resistant Staphylococcus aureus (MRSA) infections, because they are likelier to have the bacteria in their noses.
The high-risk populations are people in long-term elder care, those who are HIV-positive, and hemodialysis patients, the study found. Researchers also found that patients have vastly different quantities of MRSA in their noses, which could be used as an indicator of their risk for MRSA infection after surgery.
Dr. Leonard Mermel, medical director of epidemiology and infection control at Rhode Island Hospital, led the multi-center study, whose findings will be in the June 2010 edition of the journal Infection Control and Hospital Epidemiology and are already posted online.
Mermel worked with researchers at The Cleveland Clinic, Johns Hopkins Medical Institutions, Emory University and other organizations to obtain specimens from the noses of a variety of patients.
In general, research has shown, one in three individuals has Staphylococcus aureus, most often in the nose, and about 1 percent of U.S. residents carry MRSA in the nose, which increases the risk of MRSA infections in the blood and in surgical sites, or pneumonia.
Staphylococcus aureus is the second most common pathogen involved in U.S. health care-associated infections, and 49 percent of those cases involve MRSA.
In Mermel’s study, 444 nose cultures of 2,055 patients from 13 enrollment centers came out positive for MRSA. The high-risk populations were far likelier than average to have MRSA: 14 percent and 15 percent of inpatient and outpatient hemodialysis patients, respectively; 16 percent of HIV-infected patients, and 20 percent of those in long-term elder care.
Based on those findings, Mermel recommended that hospitals screening for MRSA give priority to those patients.
The study also found the quantity of MRSA in patients’ noses varied dramatically, from as few as three colonies, to as many as 15 million.
“This finding is important because heavy MRSA colonization of the nose is an independent risk factor for the development of a surgical site infection,” said Mermel, who is also a professor of medicine at The Warren Alpert Medical School of Brown University and a physician with University Medicine.
The study is available here.
