Pheromone cross-inhibition between Staphylococcus aureus and Staphylococcus epidermidis

Cross-inhibition by quorum-sensing pheromones between Staphylococcus aureus and Staphylococcus epidermidis was investigated using all known S. aureus agr pheromone subgroups. All S. aureus subgroups were sensitive towards the S. epidermidis pheromone, with the exception of the recently identified su bgroup 4. The subgroup 4 pheromone was also the only S. aureus pheromone ab le to inhibit the S. epidermidis agr response. The close relation of subgro up 4 to subgroup 1 suggests that subgroup 4 might have evolved from subgrou p 1 by mutation under the selective pressure of competition with S. epiderm idis. The competition between S. aureus and S. epidermidis by means of quor um-sensing cross talk seems to be generally in favor of S. epidermidis, whi ch might explain the predominance of S. epidermidis on the skin and in infe ctions on indwelling medical devices.