Background: We investigated the efficacy and cost-effectiveness of five antimicrobial regimens for mild to moderate facial acne and whether propionibacterial antibiotic resistance affects treatment response.
Methods: In this randomised, observer-masked trial, 649 community participants were allocated one of five antibacterial regimens. Primary outcomes were patients' self-assessed improvement and reduction in inflamed lesions at 18 weeks. Analyses were by intention to treat.
Findings: Moderate or greater improvement at 18 weeks was reported in 72 (55%) of 131 participants assigned oral oxytetracycline plus topical placebo, 70 (54%) of 130 assigned oral minocycline plus topical placebo, 78 (60%) of 130 assigned topical benzoyl peroxide plus oral placebo, 84 (66%) of 127 assigned topical erythromycin and benzoyl peroxide in a combined formulation plus oral placebo, and 82 (63%) of 131 assigned topical erythromycin and benzoyl peroxide separately plus oral placebo. Most improvement occurred in the first 6 weeks. Treatment differences for the proportion of people with at least moderate improvement were: minocycline versus oxytetracycline -1.2% (unadjusted 95% CI -13.3 to 10.9); combined erythromycin and benzoyl peroxide versus oxytetracycline 11.1% (-0.7 to 22.9) and versus minocycline 12.3% (0.4 to 24.2); erythromycin and benzoyl peroxide separately versus combined formulation -3.5% (-15.2 to 8.2); benzoyl peroxide versus oxytetracycline 5.0% (-7.0 to 17.0), versus minocycline 6.2% (-5.8 to 18.2), and versus combined formulation -6.1% (-17.9 to 5.7). Benzoyl peroxide was the most cost-effective treatment. Efficacy of both tetracyclines was reduced by pre-existing tetracycline resistance.
Interpretation: Topical benzoyl peroxide and benzoyl peroxide/erythromycin combinations are similar in efficacy to oral oxytetracycline and minocycline and are not affected by propionibacterial antibiotic resistance.