Abstract

Strains of Staphylococcus aureus isolated from the lesions of hospital patients were surveyed for resistance to sulphamethoxazole and to trimethoprim. Of 675 strains tested, 18·5% were resistant to sulphamethoxazole and 1·6% to trimethoprim. All the trimethoprim-resistant strains were resistant to sulphamethoxazole and to a 1:20 mixture of the two drugs. Trimethoprim-resistant strains were on average more resistant to sulphamethoxazole than were trimethoprim-sensitive strains. They were all resistant to several other antimicrobial agents. Most of them had the phage-typing pattern 84/85, 84, or 85.