Streptococci isolated from various skin lesions: the interaction with Staphylococcus aureus strains

We isolated 73 streptococcus strains (41 from infections, and 32 from colonization) from various skin diseases between March, 1994, and June, 1998. In 29 out of 41 cases of infective origin, Staphylococcus aureus strains were simultaneously isolated. Twenty-four out of 28 patients with impetigo were suffering from atopic dermatitis. We confirmed that impetigo lesions where Streptococcus pyogenes was dominant in number always showed thick-walled pustules on an erythematous base; these skin lesions were considered to be an early manifestation of streptococcal impetigo. We further confirmed that thick-crusted lesions in streptococcal impetigo, where S. aureus exceeded S. pyogenes in number, were a late manifestation. Antimicrobial agents such as minocycline, fusidic acid, ofloxacin and tosufloxacin, were more effective against S. aureus strains than against beta-hemolytic streptococcal strains. In contrast, ampicillin, cefdinir, imipenem, erythromycin and vancomycin were more effective against beta-hemolytic streptococcal strains.