Slaying MRSA: Not all OTC products created equal, study indicates

December 1, 2008

National report - An over-the-counter compound with essential oils is not only superior in completely killing community-acquired methicillin-resistant Staphylococcus aureus organisms, it also acts faster than two other OTC products for the prevention of skin and soft-tissue infections, researchers say.

Key Points

Investigators say benzethonium chloride (StaphAseptic, Tec Laboratories) with essential oils bested two other preparations in a first-of-its-kind study of differential activity of topical prevention products against the CA-MRSA strain.

Recent news reports about healthy student athletes contracting MRSA have focused the spotlight on the highly contagious disease.

"This is the population not typically considered to be at high risk of infection," he tells Dermatology Times.

A recent University of Oregon study showed that not all products kill the staph organism equally.

Study details

The study was reported in the October 2008 issue of the Journal of Antimicrobial Chemotherapy.

"The key issue we wanted to look at was how these three products compared in the speed of killing the CA-MRSA bacteria, and how completely they did that in the lab," Dr. Bearden says.

"We wanted to know how likely it was that each product would kill organisms that are on or in a wound before infection starts," he says.

Researchers tested four strains of CA-MRSA isolates: three of USA 300 and one of USA 400. They then chose three commercially available OTC topical products marketed for the prevention of wound infections: benzethonium chloride 0.2 percent tea tree oil and white thyme oil (StaphAseptic, Tec Laboratories); neomycin 3.5 mg/g and polymyxin B sulphate 10,000 U/g (Maximum Strength Antibiotic Cream, Rite Aid Corp.); and polymyxin B sulphate 10,000 U/g and gramicidin 0.25 mg/g (Polysporin Cream, Pfizer).

Upon completion of time-kill studies using a modified Food and Drug Administration (FDA) bactericidal assay technique, researchers found that at 24 hours, all three agents were superior to controls in reducing CA-MRSA organisms.

Benzethonium chloride with essential oils was more active at 24 hours than polymyxin B/gramicidin against all four strains, and more active than neomycin/polymyxin B against three of the isolates.

The role of additional essential oils in the activity of the commercial product StaphAseptic is not currently known, but the oils may play a role in its antibacterial activity, Dr. Bearden says.

"In the end, we found that the StaphAseptic ... had the most rapid killing and the most complete killing of organisms of the three products we looked at," he says.

Further studies on the product will likely be forthcoming, Dr. Bearden says.