With the rate of the most common form of methicillin-resistant Staphylococcus aureus (MRSA) infection falling in hospitals but remaining steady in the community, the biggest emerging risk factor for infection is intravenous drug use, a study published in Infection Control & Hospital Epidemiology found.
Community-associated MRSA, or CA-MRSA, initially emerged among children in day care, athletes, military personnel and in prisons, where close physical contact was thought to spread the germ. Now, risk factors include living in public housing, high-risk sexual behaviors, human immunodeficiency virus (HIV) infection and illicit drug use, according to the findings.
Illicit drug use was a significant factor for both community-acquired and hospital-onset MRSA (HO-MRSA). Researchers speculated that drug users already had MRSA when they entered the hospital.
The research focused on the USA300 strain of MRSA, which the researchers concluded is endemic in both hospital and community settings. USA300 is now more common in hospitals than the traditional hospital-acquired USA100 MRSA strain. Researchers concluded that preventative efforts focusing on illicit drug users might be required to curb MRSA infections.
The study was conducted at Cook County Hospital in Chicago, a large safety-net hospital serving a highly diverse urban population. Researchers noted that population might limit the degree to which the findings can be generalized across other hospital settings. But with similar rates of USA300 infection among U.S. inner-city populations, "the evolving epidemiology of USA300 that we demonstrated may be found in other areas."
Although the rate of hospital-onset MRSA infections has fallen in recent years, about 60 percent of 3,000 hospitals studied nationwide received the lowest or next-to-lowest scores for managing MRSA infections in a recent Consumer Reports study. However, 322 of the hospitals, or about 10 percent, reported zero MRSA infections, the study found.
Last year several prominent infection-control and healthcare organizations jointly released a set of strategies for reducing the spread of MRSA and guidance for prioritizing actions. The strategies included conducting a risk assessment, identifying ways to identify patients with a history of MRSA and to track hospital-acquired infections, ensuring compliance with hand-hygiene and physical contact protocols, and implementing an alert system to quickly contain infections.