Treatment of atopic dermatitis with 1% hydrocortisone and 25% pentane-1,5-diol: effect on Staphylococcus aureus.

372 Letters to the Editor Sir, Staphylococcus aureus is a common pathogen that may colonize normal skin, but it is not a member of the normal skin flora (1, 2). In healthy individuals it is most commonly isolated from the nose, the groin and the perineum. Patients with atopic dermatitis (AD) are colonized with S. aureus both in lesional skin as well as in non-lesional skin in 70–100% of cases (2, 3). However, the density is higher in lesional skin compared with non-lesional skin (2, 3). The reason for the increased colonization is unclear. A higher pH in the skin of patients with AD may facilitate growth of S. aureus (4). Furthermore, it has been recently demonstrated that endogenous antimicrobial peptides are decreased in atopic skin (5). As regards to the role of S. aureus colonization for AD activity, specific S. aureus IgE antibodies have been found in several patients , but their presence does not correlate with disease severity (6). However, superantigen-producing S. aureus may trigger flares in AD (6). In acute secondary bacterial infection of AD the orally active penicillase-resistant penicillins, such as flucloxacillin or dicloxacillin, are the drugs of choice (7). In patients with less severe and/or extensive signs of secondary bacterial infection, topical applied antibiotics have a documented effect (7). However, the increase in multi-resistant S. aureus, including resistance to methicillin (MRSA), fusidic acid and mupirocin, is an increasing problem (7–9). Pentane-1,5-diol (C 5 H 12 O 2) is a diol or glycol, today used as plasticizer in cellulose products and adhesives, in dental composites and in brake fluid compositions and as a preservative for grain (10). However, pentane-1,5-diol is also an effective solvent, percutaneous absorption enhancer, water-binding substance and has significant anti-microbial properties (11). Compared with propane-1,2-diol (propylene glycol) pentane-1,5-diol has the following advantages: (i) a more efficient anti-microbial agent, (ii) increased percutaneous absorption of active pharmaceutical substances, (iii) less side-effects (e.g. skin and eye irritation), and (iv) at least the same water-binding capacity (10, 11). Recently we have shown, in vitro, that pentane-1,5-diol has a high bactericidal activity against both sensitive as well as multi-resistant bacteria including MRSA, fusidic acid-resistant S. au-reus and vancomycin-resistant enterococci (9). In previous comparative studies the addition of an antibiotic to a topical steroid was considerable more effective in the treatment of AD than the topical steroid alone (7). The aim of the present study was to compare the …