Comparative in vitro activities of topical wound care products against community-associated methicillin-resistant Staphylococcus aureus.
OBJECTIVE
Community-associated methicillin-resistant Staphylococcus aureus is responsible for an increasing number of skin infections. Over-the-counter topical wound care products may play a role in the prevention of these infections, but limited data are available regarding their activity. The current study utilized a modified time-kill design to evaluate the activity of three over-the-counter topical wound care products (benzethonium chloride/essential oils, neomycin/polymyxin B and polymyxin B/gramicidin) against four unique isolates (three USA 300 and one USA 400).


METHODS
All experiments were performed using commercially available formulations. Bactericidal activity was defined as a sustained 3 log(10) reduction in cfu/mL from the initial inoculum. Reductions in bacterial counts between agents were determined using analysis of variance.


RESULTS
At 10 min, the reduction (mean +/- SD) in log(10) cfu/mL for all strains was 2.87 +/- 1.22, 1.86 +/- 0.76 and 0.143 +/- 0.82 for benzethonium chloride/essential oils, neomycin/polymyxin B and polymyxin B/gramicidin, respectively. By 24 h, bactericidal activity was observed against two strains each for neomycin/polymyxin B and polymyxin B/gramicidin. Benzethonium chloride/essential oils was bactericidal against all strains by 6 h. At 24 h, all three agents were superior to controls (P < 0.05). Benzethonium chloride/essential oils was more active at 24 h than polymyxin B/gramicidin versus all four strains (P < 0.05) and more active than neomycin/polymyxin B versus three of four strains (P < 0.05).


CONCLUSIONS
These topical agents demonstrated variable activity against the four strains tested. Benzethonium chloride/essential oils was more rapidly and completely active than the other agents tested.
Bearden
David T
DT
Oregon State University College of Pharmacy at Oregon Health and Science University, 3303 SW Bond Avenue, CH12C, Portland, OR 97239, USA. beardend@ohsu.edu
Allen
George P
GP
Christensen
J Mark
JM
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D015169:Colony Count, Microbial; D017714:Community-Acquired Infections / Q000382:microbiology*; D016106:Methicillin Resistance; D050296:Microbial Viability; D013207:Staphylococcal Skin Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013997:Time Factors
D000900:Anti-Bacterial Agents; D000891:Anti-Infective Agents, Local