Acne vulgaris: is the bacterial population size significant?

The levels of Propionibacterium acnes (P. acnes) and members of the Micrococcaceae were enumerated in two separate studies. The first investigation on the foreheads of thirty-five mild and thirty-five moderate acne patients showed no significant difference in the bacterial populations of the two groups. The second investigation of twelve patients on 250 mg tetracycline twice daily for 3 months showed no significant difference compared to pre-treatment data in the bacterial population during the successful treatment period. The data indicate that greater numbers of bacteria are not associated with increasing severity of acne and that the effectivenss of oral tetracycline in treating the disease can not be explained by a reduction in the number of viable bacteria.