Skin occlusion: Effect on Pityrosporum orbiculare, skin $$P_{{\text{CO}}_{\text{2}} } $$ , pH, transepidermal water loss, and water content

Abstract

The effect of 8 days skin occlusion on Pityrosporum orbiculare, bacteria, skin PCO2, pH, transepidermal water loss (TEWL), and water content (WC) was studied. P. orbiculare counts increased from a baseline of 2.1 X 10(2)/cm2 to 2.3 X 10(3)/cm2 after 3 days occlusion; bacterial counts increased from 2.9 X 10(3)/cm2 to 1.8 X 10(5)/cm2 after 8 days occlusion. pH increased during occlusion from 5.6 to a maximum at day 3 of 6.7; TEWL increased to a maximum of 11.74 g m-2 h- after 3 days occlusion compared with 4.39 g m-2 h-1 before. P. orbiculare counts, pH, and TEWL were lower at 8 days than at 3 days occlusion. WC and PCO2 remained high after 8 days; relative WC was then 60.6% compared with 52.5% before occlusion; PCO2 was 63.1 mm Hg compared with 53.1 mm Hg before occlusion. The increased levels of these factors may partially explain the higher risk of infection in occluded compared with non-occluded skin.

Occlusion vs. skin barrier function

“…Water content can be increased up to 50% with occlusion (3, 4): even short time (30 min) exposure can result in significantly increased stratum corneum hydration (33). With 24 h occlusion, the relative water content in stratum corneum can be increased significantly from 53% without occulsion to 59% with occlusion (20). 24 h occlusion can induce morphological changes on the surface, deepening skin furrows (22).…”

“…Wound dressings have been employed to speed the healing processes in acute and chronic wounds by keeping healing tissues moist and increasing superficial wound epithelialization (2,16,17). However, occlusive or semiocclusive dressings can increase microorganisms and hence induce wound infections (2,(18)(19)(20)(21). A significant increase in the density of Staphylococcus aureus and lipophilic diphtheroids were observed after 24 h occlusion in eczematous and psoriatic skin (19).…”

Effects of Skin Occlusion on Percutaneous Absorption: An Overview

“…Occlusion may enhance drug efficacy [5][6][7][8][9][10]. Ac- Zhai/Maibach tually, skin occlusion is a complex event producing profound changes and influencing skin biology as well as wound healing processes [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. In general, occlusion can, with exceptions [2,4,28,29], increase percutaneous absorption of topically applied compounds [30][31][32][33][34][35][36][37][38][39][40][41][42]; even a short-time (30 min) occlusion can result in significantly increased penetration and horny layer water content [43].…”

Occlusion Effect on in vivo Percutaneous Penetration of Chemicals in Man and Monkey: Partition Coefficient Effects

“…In fact, evidence suggests skin occlusion is more complex than previously thought as it can induce changes in epidermal lipid content, DNA synthesis, epidermal turnover, skin pH, epidermal morphology, sweat glands, and Langerhans cell stresses [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]. This overview focuses on what effect occlusion has on the percutaneous absorption of compounds of varying lipophilicities/hydrophilicities in vivo in the monkey and man; a companion review discusses the effect occlusion has on the in vitro percutaneous absorption of compounds of varying partition coefficients [submitted].…”