Synergism of polymyxin and sulfonamides in L-forms of Staphylococcus aureus and Proteus mirabilis.

Earlier workers suggested that synergism of polymyxin and sulfonamides occurred because sulfonamides produced changes in the cell wall which permitted the more ready access of polymyxin. We tested this hypothesis by using L-forms, which lack cell wall. The demonstration that synergism of polymyxin and sulfonamides occurs in L-forms of Proteus mirabilis and Staphylococcus aureus suggested that the synergism is a result of some mechanism other than alterations of the cell wall.