Study: Antibiotic Ointments May Aid Spread of MRSA
Researchers Suggest That Antibiotic Ointments May Be a Factor in Spread of Strain Called USA300
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Bacitracin is among the active ingredients in Neosporin and Polysporin ointments and generic versions of those products. Neomycin is an active ingredient in Neosporin ointment.
Nearly half of the USA300 samples grew unhampered by the antibiotics bacitracin and neomycin, indicating that they were resistant to those drugs. Another USA300 sample was resistant to bacitracin, but susceptible to neomycin.
In contrast, none of the 240 samples of other MRSA strains found in Japan were resistant to bacitracin, though more than half of the other strains demonstrated at least partial resistance to neomycin.
"I think this indicates that spreading of USA300 may be related with problems in North America, specifically," says study researcher Yoshitsugu Iinuma, MD, PhD, professor in the department of infectious diseases at Kanazawa Medical University in Ishikawa, Japan, in an email. Iinuma notes that antibiotic ointment is rarely used in countries outside North America.
Johnson & Johnson, the manufacturer of Neosporin and Polysporin, say the researchers haven't proven a connection between the use of the ointments and resistance to the antibiotics in them.
"This small study did not evaluate any relationship between development of resistance to bacteria and the usage of over the counter antibiotic ointments for the prevention of infection and the authors themselves convey that further research would be needed to reach any significant conclusions," says Jodie Wertheim, a spokeswoman for the company, in an email. "It should also be noted that antibiotic ointments have been used safely for years to provide a broad-spectrum of protection against a wide variety of germs."
More Study Needed
Experts who reviewed the study say that while its findings are intriguing, they need to be duplicated on a larger scale before any firm conclusions can be made about the role of antibiotic ointments in MRSA spread or resistance.
"This study is a first step to saying 'Hey, there may be a real problem here,'" says Lance Price, PhD, associate professor of pathogen genomics at the Translational Genomics Research Institute in Flagstaff, Ariz. "So now we need to do a multi-nation study to really look at this."