Inhibition of growth and swarming of Proteus mirabilis and Proteus vulgaris by triclosan.

The MICs of triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) and the effect on swarming were determined for 35 isolates of Proteus mirabilis and 7 isolates of P. vulgaris of animal origin. Both species were susceptible to the antimicrobial agent, and growth of all but one isolate was inhibited by less than 1 microgram/ml in broth and on agar without blood. Swarming was inhibited at triclosan concentrations two- to fourfold less than the MICs. Higher concentrations were required with blood agar than with plain agar for inhibition of growth and swarming.