PITYROSPORUM-OVALE IN HEALTHY-CHILDREN, INFANTILE SEBORRHEIC DERMATITIS AND ATOPIC-DERMATITIS

The occurence of Pityrosporum ovale was studied in healthy children, c hildren with infantile seborrhoeic dermatitis (ISD) and in patients wi th atopic dermatitis (AD). Twenty children with ISD and twenty healthy infants were subjected to culture for P. ovale. Positive cultures wer e found in 18 of 20 infants with ISD, compared with 4 of 20 controls. The same culture medium containing olive oil as one of the lipids was used to evaluate the frequency of positive P. ovale cultures in 60 pat ients with AD, 40 patients with rhinoconjunctivitis and/or asthma (RA) and 40 children and young adults with no atopic history (HC). The res ults of the quantitative cultures from the forehead did not differ bet ween the groups. P. ovale cultures were positive in 0-20% of children aged 0-10 years and in 60-90% of the 11-20-year-old subjects. Positive P. ovale cultures were found in 87 % of 138 healthy children aged 2 m onths to 15 years when cultures were performed on a medium containing whole fat cows' milk as one lipid source. The largest number of coloni es was found among children aged 2-23 months and among children older than 9 years. The occurrence of specific IgE antibodies to P. ovale wa s evaluated with a skin prick test (SPT) and RAST and compared in 3 gr oups (AD, RA, HC) of patients aged 0-20 years. Specific IgE were found most often in patients with AD. In patients with AD on different part s of the body, 15 % had a positive SPT to P. ovale. In another group o f patients, aged 14-53 years, with AD localised mainly to the head and neck area, the SPT was positive in 55% of the patients. Sera from 13 patients with positive SPT to P. ovale were further analysed with IgE immunoblotting using both P. ovale and C. albicans antigens. Simultane ous IgE-binding to both these yeasts was found in 5 sera and these wer e analysed with RAST-inhibition, Cross-reacting IgE antibodies to P. o vale and C. albicans were found in two of these sera. Cross-reacting s era were pooled and used as an IgE probe in crossed radioimmunoelectro phoresis and Tandem-crossed immunoelectrophoresis. Cross-reacting epit opes were suggested to be located in the mannan polysaccharide of C. a lbicans and in a high molecular weight fraction of P. ovale. To evalua te the effect of topical antimycotic treatment in patients with AD aff ecting the head and neck area, 53 patients aged 28 years (range 14-53 years) were included in a double-blind study for 6 weeks. In addition to oral antibiotic treatment, patients in one group were given miconaz ole-hydrocortisone cream and ketoconazole shampoo whereas patients in the other group were given hydrocortisone cream and placebo shampoo. A fter 4 weeks' treatment, there was a decrease in P. ovale colonisation in the group given the antimycotics but not in the placebo group. The decrease in eczema score did not differ between the groups. In conclu sion, we found that patients with AD harboured P. ovale on the skin in the same frequency as patients with or without other atopic manifesta tions. Sensitisation to this yeast was found most often in AD but alth ough topical antimycotic treatment was effective in decreasing the amo unt of P. ovale on the skin no additional therapeutic effect was noted .