Effects of various salts and irradiation with UV light on the attachment of Staphylococcus aureus strains

We investigated the attachment of Staphylococcus aureus isolated from atopic dermatitis lesions to plastic tissue-culture coverslips. We found that attachment was weaker in (rabbit) plasma with 5 or 10% NaCl and in plasma with 5 or 10% sea salts than in the control plasma after incubation for 2 h (P < 0.01). The attachment was weaker still in plasma with 10% NaCl or 10% sea salts than in the control plasma after incubation for 24 h (P < 0.01). Plasma coagulation of four S. aureus strains isolated from atopic dermatitis lesions was not detected in plasma with 10% NaCl (pH 5.6) or 10% sea salts (containing 0.372% Mg²⁺) after incubation for 12, 24, 36 and 60 h. The attachment of S. aureus strain cells to the coverslip in plasma was weaker after irradiation with UVA at 25 or 50 J/cm² (P < 0.01) and UVB at 0.5 J/cm² (P < 0.05) both of which are covered by a black cloth, than without irradiation after incubation for 24 h. Plasma coagulation was not detected after irradiation with UVA at 25 or 50 J/cm² with a black cloth cover (temperature reached 50°C), but was detected after UVA irradiation at the same doses combined with cooling (temperature reached 22°C), after incubation for 24 h. The results suggest that the attachment of S. aureus cells isolated from atopic dermatitis lesions to the coverslip is suppressed in the presence of 10% salts and irradiation with UVA and UVB, and that plasma coagulation of S. aureus cells isolated from atopic dermatitis lesions is suppressed in the presence of 10% salts, irradiation with UVA, and heating.