Staphylococcus aureus biofilms promote horizontal transfer of antibiotic resistance.

Growth as a biofilm facilitates the emergence of antibiotic resistance by mutation in Staphylococcus aureus. Here we demonstrate that biofilm growth of this species also dramatically increases horizontal transfer of plasmid-borne antibiotic resistance determinants by conjugation/mobilization and that standard laboratory practices to induce conjugation in staphylococci achieve optimal efficiency owing to the presence of a biofilm.