Excerpt from Propionibacterium Infections

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Background

Propionibacterium species are inhabitants of the skin and usually are nonpathogenic. As a result, they are common contaminants of blood and body fluid cultures. These species are slow-growing, nonsporulating, gram-positive anaerobic bacilli.

Propionibacterium species belong to the genera of Coryneforms and are the best studied because of their association with acne vulgaris. However, a number of other infections may be caused by Propionibacterium species, and these are described briefly in this article.

Propionibacterium acnes is found briefly on the skin of neonates, but true colonization begins during the 1-3 years prior to sexual maturity when numbers rise from fewer than 10/cm² to about 10⁶/cm², chiefly on the face and upper thorax. In the lipid-rich microenvironment of the hair follicle, P acnes produces inflammatory mediators that result in papules, pustules, and later, nodulocystic lesions that are typical of inflammatory acne.

Propionibacterium granulosum is found in the same areas but at numbers about one hundredth of those of P acnes.

Both P acnes and P granulosum may be isolated from the gastrointestinal tract.

Propionibacterium avidum is found in the axilla, rather than on exposed areas, and increases in numbers at puberty.

Propionibacterium propionicus has been implicated as a less common causative agent of a disease process similar to actinomycosis. The most common cause of actinomycosis is Actinomyces israeli.

Frequency

United States

Acne vulgaris is sufficiently common that it may be considered physiologic.

Race

Acne appears to be a familial condition and is less common in Japanese people than in the white American population.

Sex

In girls, acne may precede menarche by more than 1 year. The greatest number of cases is observed during the middle-to-late teenage period, and incidence decreases subsequently. Males are affected more frequently than females are, and males tend to have more severe involvement.

Age

Acne vulgaris is a self-limited disease involving the sebaceous follicles observed primarily in adolescents. Occasionally, it is present at birth, and mild cases may be observed in the neonatal period. During puberty, acne typically becomes a common problem. The condition often is an early manifestation of puberty. In very young patients, the predominant lesions are comedones, and inflammatory lesions are rare.

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