Staphylococcus aureus in chronic and recurrent infections.

Ninety-four Staphylococcus aureus strains isolated from chronic and recurrent skin and respiratory tract infections were investigated for several virulence factor expressions. Production of protein A was noticed in all of the tested strains in amounts from less than 0.1 to more than 2.5 ng per 10(6) bacterial cells. The percentage of the extracellularly produced protein A was found to lie between 4.5 and 27.8%. Two strains (both from the respiratory tract) produced more than 50% of protein A in the extracellular form and one strain did not produce any detectable amount of the extracellular protein A; 99% of the tested strains produced the clumping factor, 96% staphylocoagulase, 79% staphylokinase and 90% gelatinolytic activity; 79% produced alpha-toxin exclusively or in combination with delta- or beta-toxin; 8% of strains produced beta-toxin. There were differences in beta-toxin production between strains from the respiratory tract (5%) and skin infections (25%). delta-Toxin was produced by 53% of the strains. In each of the tested strains a complex of virulence factors was detected. The importance of inactivated extracellular products (especially alpha- and delta-toxin and in the case of skin infections also beta-toxin) as components of staphylococcal whole-cell vaccine was suggested.