Background: Inflammatory, medium to severe acne vulgaris is treated with systemic antibiotics worldwide. The rationale is an effect on Propionibacterium acnes as well as the intrinsic anti-inflammatory properties of these antibiotics. Although there are no correlations between the number of P. acnes and the severity of the disease, associations between the degree of humoral and cellular immune responses towards P. acnes and the severity of acne have been reported. Exact data on practical use of these compounds, such as differential efficacy or side effects are unavailable. A summary of currently available studies is presented.
Methods: The data of studies of systemic antibiotic therapy of acne vulgaris up to 1975, the summary of literature in English up to 1999, a systematic review of minocycline from 2002 as well as the data of randomized controlled studies published and listed in Medline thereafter were reviewed.
Results: Tetracyclines [tetracycline 1,000 mg daily, doxycycline 100 (-200) mg daily, minocycline 100 (-200) mg daily, lymecycline 300 (-600) mg] and erythromycin 1 000 mg daily are significantly more effective than placebo in the systemic treatment of inflammatory acne. The data for tetracycline are best founded. Clindamycin is similarly effective. Co-trimoxazole and trimethoprim are likely to be effective. Clear differences between the tetracyclines or between tetracycline and erythromycin cannot be ascertained. The data for the combination with topical treatments [topical benzoyl peroxide (BPO) or retinoids] suggest synergistic effects. Therefore systemic antibiotics should not be used as monotherapy. In case of similar efficacy, other criteria, such as pharmacokinetics (doxycycline, minocycline, lymecycline have longer half-lives than tetracyclines), the rate of side-effects (tetracycline: side effect-rate approximately 4 % mild side effects; erythromycin: frequent gastrointestinal complaints; minocycline: rare, but potentially severe hypersensitivity reactions; doxycycline: dose-dependent phototoxic reactions), the resistance rate [percentage of resistant bacteria higher with erythromycin (approximately 50 %) than with tetracycline-therapy (approximately 20 %)], and the costs of therapy have to be taken into account.
Conclusions: The systemic antibiotic therapy of widespread papulo-pustular acne not amenable to a topical therapy is effective and well-tolerated. In general therapy can be carried out for 3 months and should be combined with BPO to prevent resistance.