New horizons for cutaneous microbiology: the role of biofilms in dermatological disease.

Human skin is colonized by bacteria. The development of new genomic microbiological techniques has revealed that the bacterial ecology of human skin is far more complex than previously imagined and includes many fastidious or noncultivable bacterial species which are found on both normal and diseased skin. In nature, the predominant bacterial phenotype on epithelial surfaces is that of organisms organized within a biofilm. This contrasts with the widely held belief that bacteria are planktonic, i.e. free-floating single cells. Biofilms are sessile bacterial communities encased in an extracellular matrix that have a well-developed communication system and can regulate bacterial growth and metabolism, confer resistance to antimicrobials and to host inflammatory cells, and alter host metabolism. Biofilms have been observed on healthy skin and in a number of dermatological conditions, including some that were previously thought not to have an infectious aetiology. Here we review the concept of biofilms and their role in cutaneous health and disease.

The role of extracellular polysaccharide substance produced by Staphylococcus epidermidis in miliaria.

BACKGROUND: Previous studies have indicated that cutaneous bacteria, particularly coagulase-negative staphylococci, play a role in the pathogenesis of miliaria. An accumulation of periodic acid-Schiff (PAS)-positive material has been described as blocking the sweat duct in miliaria. Furthermore, a PAS-positive extracellular polysaccharide substance (EPS) has been identified as a product of some strains of Staphylococcus epidermidis. OBJECTIVE: We evaluated the relative ability of various species of coagulase-negative staphylococci to induce miliaria with particular reference to the potential role of EPS. METHODS: We inoculated various strains of coagulase-negative staphylococci on the volar forearms of subjects under an occlusive dressing coupled with thermal stimulation. Ability to induce miliaria as well as microbiologic, histologic, and immunostaining features were evaluated. RESULTS: Miliaria was induced only with strains of S. epidermidis; other species including S. haemolyticus, S. hominis, S. cohnii, S. saprophyticus, and S. simulans were not capable of inducing miliaria. Moreover, only S. epidermidis strains capable of producing EPS were capable of inducing miliaria. CONCLUSION: Our data indicate that EPS is the PAS-positive material that obstructs the delivery of sweat to the skin surface in miliaria and therefore demonstrate that the EPS produced by S. epidermidis plays a central role in the pathogenesis of miliaria. Furthermore, in a survey of staphylococcal flora isolated from 68 subjects, EPS-producing strains were found to be common.

An outbreak of periporitis staphylogenes of complex origin.

During the summer 1971 an outbreak of periporitis staphylogenes occurred among newborn in Horsens Hospital. 23 babies (16 boys and 7 girls) were infected with Staphylococcus aureus resistant to penicillin. Some of them also developed pemphigus neonatorum and sweat gland abscesses. Phage typing of staphylococci from the infected babies indicated, that some had acquired bacteria from the hand-eczema of a midwife and others from a doctor carrying Staphylococcus aureus, in his nose.

The pathogenesis of miliaria rubra. Role of the resident microflora.

Anhidrosis was induced in volunteers by covering the skin with an impermeable plastic film. The degree of sweat suppression and miliaria after a thermal stimulus was directly proportional to the increase in the density of resident aerobic bacteria, notably cocci. No anhidrosis resulted when antibacterial substances were used to prevent the expansion of the microflora. Histological study showed a PAS-positive diastase resistant amorphous mass deep within the acrosyringium after 2 days of occlusion, accompanied by a periductal dermal infiltration of leukocytes. After another 2 days the duct became clogged by an amalgam of degenerating leukocytes. This impaction sloughed after about 3 weeks as a result of epidermal renewal. Colonies of bacteria were never found within the ducts. It is postulated that cocci secrete a toxin which injures luminal cells and precipitates a cast within the lumen. Infiltration by leukocytes creates an impaction which completely obstructs the passage of sweat for several weeks.