Acapsular clinical Staphylococcus aureus isolates lack agr function.

Staphylococcus aureus is a major human pathogen causing community- and hospital-acquired infections. Capsule production of S. aureus confers protection against host defence. There is a lack of information concerning the association of capsular polysaccharide (CP) expression and activity of the accessory gene regulator (agr) in clinical S. aureus isolates. Production of CP and agr expression were assessed in 195 S. aureus isolates from infected patients at a German University Hospital. Northern blot analysis revealed that S. aureus strains with a non-functional agr locus were more likely to be CP-negative than strains with a functional agr locus.