[Tetracycline resistance and beta-lactamase production in pharyngeal commensal Neisseria].

Commensal Neisseria may constitute a potential source of resistance genes transferable to pathogenic Neisseria. We tested 150 strains of commensal Neisseria isolated from throat cultures for resistance to tetracycline and beta-lactamase production. Seven strains were high level tetracycline resistant (MIC greater than 16 mg/ml), and minocycline resistant. Only one strain carries a 40 kilobases plasmid. Seven strains were tetracycline resistant (MIC = 8 or 16 mg/l) and minocycline susceptible. Three strains were beta-lactamase producers. These strains were identified as Neisseria perflava or Neisseria sica.