Prevalence of the ermB gene in Clostridium difficile strains isolated at a university teaching hospital from 1987 through 1998.

We analyzed 226 strains of Clostridium difficile for the presence of erythromycin ribosomal methylase B (ermB) genes. Forty-four strains (19.4%) carried ermB genes and were resistant to erythromycin. Toxin A and toxin B gene sequences were identified in 81.9% of these 44 strains. Strains of C. difficile that carry ermB genes are common etiologic agents of C. difficile-associated diarrhea.