The cutaneous microflora of adolescent, persistent and late-onset acne patients does not differ.

The cutaneous microbiology and antibody status to Propionibacterium acnes of patients with persistent (males, n = 32; females, n = 33) and late-onset (females, n = 25) acne were compared with individuals with adolescent acne (males, n = 22; females, n = 18) and normal control volunteers (persistent acne: males, n = 26; females, n = 30; late-onset: females, n = 20). Males had significantly higher grades of acne compared with females (P < 0.05). The microflora consisted in the main of propionibacteria, staphylococci and Malassezia; other bacteria represented less than 0.01% of the total microflora. At all sites for all samples there were significantly more propionibacteria than staphylococci or Malassezia (P < 0.05). There were significantly higher (P < 0.05) numbers of microorganisms in follicular casts from patients compared with their control volunteers for female facial skin and male back skin. Twenty-six papules and 48 normal follicles were analysed. A bimodal distribution of microbial colonization was noted, with about 90% of normal follicles and about 10% of acne follicles having no detectable viable microorganisms. Anti-P. acnes IgG antibody titres were measured using a secondary fluorescein isothiocyanate antibody technique, and no significant differences in titre were found between any groups of patients (P > 0.05). Correlation analysis showed no association between the population densities of P. acnes and anti-P. acnes IgG titres. There were no differences in the microbiology of skin of adolescent acne patients, persistent acne patients or late-onset acne patients which could account for these various forms of acne.