Bacteriology of pustular acne

The production of inflammatory compounds by Propionibacterium acnes and other skin organisms

Culture supernatants from four species of skin microorganisms (P. acnes, P. avidum, P. granulosum and S. epidermidis) were assayed for smooth muscle contracting substances which are indicative of inflammatory activity. At least three types of smooth muscle contracting substances were detected. These were: first, a substance active on a rat fundic strip preparation and antagonized by N,N-DMT. Activity was enhanced when cultures were grown in the presence of tryptophan. This substance was probably tryptamine. Second, a substance active on a guinea-pig ileum preparation and antagonized by mepyramine. Activity was enhanced when cultures were grown in the presence of histidine. This substance was probably histamine. Third, a substance active on a rat fundic strip preparation but not antagonized by N,N-DMT, mepyramine, atropine or indomethacin. Activity was enhanced when cultures were grown in the presence of glucose. This activity was probably due to acetate, propionate or other short-chain fatty-acid salts. Chromatographic analysis confirmed the presence of histamine, tryptamine and short-chain fatty acids in the culture supernatants. These substances if produced in vivo may cause or contribute to inflammation and pain directly without the prior mediation of the immune system. Cell extracts of Propionibacterium species were analysed by bioassay for the presence of prostaglandin-like compounds. These could not be detected in any of the eight strains of organisms tested.

Evaluation of a therapeutic strategy for the treatment of acne vulgaris with conventional therapy

Four hundred and twenty patients with moderate to severe acne vulgaris were treated with oral erythromycin and topical benzoyl peroxide to determine the optimum dose regimes. Our results show that the response was significantly less in patients with a greater severity of acne, with truncal acne and in those with a higher sebum excretion rate. There was a significantly better clinical result in patients given Ig erythromycin daily than in those given 0.5 g daily (plus topical therapy in both groups). The relapse rate on stopping antibiotics is also significantly less in patients given I g daily and this dosage did not produce any increase in side effects. We suggest that any patient requiring oral antibiotics should initially be given I g daily of erythromycin (or tetracycline) for up to six months, plus topical therapy.

Cellular immunity to P. acnes in the normal population and patients with acne vulgaris

Patients with varying degrees of acne, acne-free adult controls and samples of cord blood were investigated for cell mediated immunity to P. acnes using a leukocyte migration inhibition test. Despite the fact that the mean migration index tended to decrease with acne severity, only the patients with severe acne showed cell-mediated immunity. It is suggested that when cellular immunity arises it is a late event which may contribute to inflammation but is probably not a factor in its initiation.

Lymphocyte transformation in subjects with nodulo cystic acne

Patients with severe nodulo-cystic acne are known to have elevated serum antibody levels and increased immediate hypersensitivity reactions to Propionibacterium acnes. This organism is the predominant bacterium in normal pilosebaceous follicles of human skin, and can be consistently isolated from pustular lesions in acne. Previously it had been observed that delayed cutaneous hypersensitivity reactions to P. acnes were negative in patients with acne. The present study investigated the proliferative response of lymphocytes from patients with nodulo-cystic acne to phytohaemagglutinin (PHA) and P. acnes antigen stimulation. The response to PHA stimulation was within normal limits. The response to P. acnes antigen showed a significant increase over control values obtained by testing lymphocytes from acne-free subjects. Thus cell mediated immunity to P. acnes may be present in subjects with severe inflammatory acne. These findings raise the possibility that reactions to P. acnes may contribute to intensifying the inflammatory response in acne lesions.

Acne vulgaris: an investigation into the number of anaerobic diphtheroids and members of the Micrococcaceae in normal and acne skin

A quantitative study was made of the microflora of 174 acne and 68 non-acne subjects. Two groups of organisms were investigated, the anaerobic diphtheroids and members of the Micrococcaceae. The results showed high numbers of both groups of bacteria in skin bearing blackheads, papules or pustules and in non-acne adolescent skin. There were significantly lower numbers of bacteria in the pilosebaceous ducts of normal looking skin in acne areas and in pre-adolescent skin when compared with non-acne adolescent skin. It is suggested that increased numbers of bacteria alone do not predispose to acne, but that their interaction with the skin, which is a function of the localized skin environment, may be important.

Quantification of bacteria in isolated pilosebaceous follicles in normal skin

A technique for quantitating bacteria in isolated pilosebaceous follicles is described. This involves microdissection of the follicles from biopsies of skin, using the method of chemical pretreatment of skin to facilitate the separation of the epidermis and epidermal appendages from the dermis. The aerobic cocci and anaerobic diphtheroids in pilosebaceous follicles in 66 biopsies of scalp and 48 biopsies of skin of the upper back were quantitated using this technique. On the back, aerobic staphylococci were very sparse in normal follicles, indicating that their primary habitat on the skin must be on the skin surface rather than within follicles. Of 138 isolated follicles from skin of the upper back, 94 contained no aerobic cocci. Anaerobic organisms were present in high numbers within normal follicles. The geometric mean density of anaerobes in 138 isolated follicles from skin of the upper back was 3.8 X 10(4) diphtheroids per follicle. Eighty-eight follicles contained more than 10(4) anaerobic diphtheroids. Using data from scalp biopsies we found that there was a correlation between the weight of sebaceous glands and the density of anaerobes within the follicles attached to these glands (coefficient of correlation = 0.6).

Anti-inflammatory effects of antimicrobial agents: an in vivo study

Antimicrobials are used emperically in a variety of inflammatory dermatoses such as rosacea and dermatitis herpetiformis, although these diseases are not believed to be of bacterial etiology. We have used potassium iodide ointment to induce follicular pustules and have found in this in vivo model properties of antimicrobials not related to their antibacterial actions. Topical demethylchlortetracycline and erythromycin (5%) lead to suppression of KI-induced inflammation (erythema, pustules) and systemic use of these drugs as well as diaminodiphenylsulfone produces the same effect.

The localization and distribution of gram-positive cocci in normal skin and in lesions of acne vulgaris

The localization of gram-positive cocci in the normal skin and in the lesions of acne vulgaris was investigated using fluorescein-labeled antiserum raised to gram-positive, coagulase-negative cocci. The cocci were found in 10 of 19 specimens from normal facial skin and in 3 of 11 specimens from the normal skin of the rest of the body. The bacteria were found mostly in the openings of follicles, but in 6 of 10 facial skin specimens, they were also present deeply in the lumina of the dilated sebaceous follicles near the sebaceous glands. Cocci were found in 5 of 6 noninflammatory acne comedones. In inflammatory acne they were demonstrated not only in the follicular canals but also sparsely in the infiltrate surrounding the follicles.

Quantitative microbiology of the scalp in non-dandruff, dandruff, and seborrheic dermatitis

The composition of the scalp microflora was assessed quantitatively in normal individuals and in patients with dandruff and seborrheic dermatitis, disorders characterized by increasing scaling. Three organisms were constantly found: (1) Pityrosporum, (2) aerobic cocci, and (3) Corynebacterium acnes. Pityrosporum (mainly Pityrosporum ovale) made up 46% of the total microflora in normals, 74% in dandruff, and 83% in seborvheic dermatitis. The geometric mean number of organisms per cm-2 in non-dandruff subjects was 5.04 times 10-5; 9.22 times 10-5 in dandruff subjects; and 6.45 times 10-5 in those with seborrheic dermatitis. The cocci were dominantly Baird-Parker type SII and no quantitative or qualitative change occurred in the scaling disorders. C. acnes comprised 26% of the flora on the normal scalp, 6% in dandruff, and only 1% in seborrheic dermatitis. These results differ significantly from previous reports which describe a much more complex microflora and suggest an etiologic role for microorganisms in dandruff.