Notes: Summary Background Propionibacterium acnes and P. granulosum are widely regarded as the aetiological agents of inflammatory acne. Their proliferation and metabolism are controlled using lengthy courses of oral and/or topical antibiotics. Despite numerous reports of skin colonization by antibiotic-resistant propionibacteria among acne patients, accurate prevalence data are available only for the U.K. Objectives To determine the prevalence of skin colonization by antibiotic-resistant propionibacteria among acne patients and their contacts from six European centres. Methods Skin swabs were collected from 664 acne patients attending centres in the U.K., Spain, Italy, Greece, Sweden and Hungary. Phenotypes of antibiotic-resistant propionibacteria were determined by measuring the minimum inhibitory concentrations (MIC) of a panel of tetracycline and macrolide, lincosamide and streptogramin B (MLS) antibiotics. Resistance determinants were characterized by polymerase chain reaction (PCR) using primers specific for rRNA genes and erm(X), followed by nucleotide sequencing of the amplified DNA. Results Viable propionibacteria were recovered from 622 patients. A total of 515 representative antibiotic-resistant isolates and 71 susceptible isolates to act as control strains were characterized phenotypically. The prevalence of carriage of isolates resistant to at least one antibiotic was lowest in Hungary (51%) and highest in Spain (94%). Combined resistance to clindamycin and erythromycin was much more common (highest prevalence 91% in Spain) than resistance to the tetracyclines (highest prevalence 26·4% in the U.K.). No isolates resistant to tetracycline were detected in Italy, or in Hungary. Overall, there were strong correlations with prescribing patterns. Prevalence of resistant propionibacteria on the skin of untreated contacts of the patients varied from 41% in Hungary to 86% in Spain. Of the dermatologists, 25 of 39 were colonized with resistant propionibacteria, including all those who specialized in treating acne. None of 27 physicians working in other outpatient departments harboured resistant propionibacteria. Conclusions The widespread use of topical formulations of erythromycin and clindamycin to treat acne has resulted in significant dissemination of cross-resistant strains of propionibacteria. Resistance rates to the orally administered tetracycline group of antibiotics were low, except in Sweden and the U.K. Resistant genotypes originally identified in the U.K. are distributed widely throughout Europe. Antibiotic-resistant propionibacteria should be considered transmissible between acne-prone individuals, and dermatologists should use stricter cross-infection control measures when assessing acne in the clinic.

Notes: Background This NHS/HTA-funded study aimed to rank five commonly used antimicrobial therapies for acne in order of their clinical effectiveness and cost-effectiveness. We also wanted to identify which agents are less likely to promote resistance and those which are effective in patients who harbour high numbers of resistant Propionibacterium acnes strains. Methods From surgeries and colleges in the Nottingham and Leeds areas, 649 patients with mild to moderate facial acne were recruited. The two primary outcome measures were patient self-assessment of improvement in overall acne severity and reduction in inflamed lesion count, measured at 18 weeks. Secondary outcome measures included two acne severity scores, assessors' global estimation of improvement, quality of life and utility scores, enumeration of antibiotic resistant propionibacteria, and the incidence of adverse events. Results and Conclusions The most effective treatments (percentage with at least moderate improvement according to patients, mean change in lesion count) were the topical Benzamycin® b.d. (66%, − 27) and its components given separately (topical erythromycin o.d. + 5% benzoyl peroxide o.d.) (63%, − 26), followed by 5% benzoyl peroxide b.d. (60%, − 23). The least effective were oral oxytetracycline (55%, − 18) and minocycline (54%, − 22). The most cost-effective treatment was benzoyl peroxide and least cost-effective was minocycline. In terms of quality of life, benzoyl peroxide moved down the rankings and minocycline moved up. The two topical erythromycin-containing regimens produced the largest reductions and the oral treatments the smallest in the prevalence and population density of cutaneous propionibacteria. Prior bacterial colonisation did not affect outcome in the topical groups. Efficacy of both oral preparations was influenced by tetracycline resistant P. acnes strains. Disclaimer The views and opinions expressed are those of the authors and do not necessarily reflect those of the Department of Health.