No abstract

Propionibacterium species were quantified on the foreheads and cheeks of persons with and without acne in three age groups: 11 to 15, 16 to 20, and 21 to 25. Propionibacteria were virtually absent in the pubertal non-acne group compared to a geometric mean density of 114,800 per sq cm in the acne group. A similar sharp difference existed between the acne subjects and normals in the age range of 16 to 20 years: 85,800 organisms per sq cm compared to 588 per sq cm. Patients with acne and normal subjects over age 21 showed no difference in Propionibacterium levels. In acne patients, while there was a trend for lower levels, no significant difference was seen as the severity of inflammation increased.

Quantitative levels of resident aerobic and anaerobic bacteria of the face, show a characteristic age-related pattern. The density of anaerobic diptheroids and surface aerobic micrococci is higher in infancy than in early childhood. At puberty the quantity of organisms increases, with significantly higher levels achieved in late adolescence. Maximum counts are attained in early adulthood and remain constant until old age when a trend toward lower numbers occurs. These changes seem to correlate with the production of sebum.

Although acne has traditionally been viewed as predominantly affecting adolescents, a significant and growing body of literature suggests an adult (i.e. post-adolescent) form of the disease. This review summarizes selected publications on post-adolescent acne, and discusses possible causes and treatment options. Recent epidemiological studies show that there appears to be an increase in post-adolescent acne, and that the disease is lasting longer and is requiring treatment well into the mid forties. There is good agreement that, unlike teenage acne, where males tend to show the most severe forms of the disease, post-adolescent acne mainly affects females (the lesions are frequently perioral and occur premenstrually) and that there are two forms of the disease. The terms 'persistent' and 'late onset' are now generally accepted as describing these two types. The causes of post-adolescent acne remain to be fully elucidated and hormones, colonization by resistant bacteria and the use of cosmetics have been put forward and debated in the literature. Additionally, some clues to the cause of post-adolescent acne may be gleaned from an individual's response to therapy. Perhaps one of the most intriguing explanations for the increase in this disease is the proposed relationship between increasing stress levels, androgen hormones and increasing levels of acne found in women in fast paced jobs.

A 2.5% formulation of benzoyl peroxide was compared with its vehicle, and with a 5% and a 10% proprietary benzoyl peroxide gel preparation in three double-blind studies involving 153 patients with mild to moderately severe acne vulgaris. The 2.5% benzoyl peroxide formulation was more effective than its vehicle and equivalent to the 5% and 10% concentrations in reducing the number of inflammatory lesions (papules and pustules). Desquamation, erythema, and symptoms of burning with the 2.5% gel were less frequent than with the 10% preparation but equivalent to the 5% gel. The 2.5% formulation also significantly reduced Propionibacterium acnes and the percentage of free fatty acids in the surface lipids after 2 weeks of topical application.