Resistance of Providencia stuartii to chlorhexidine: a consideration of the role of the inner membrane.

Spheroplasts of three strains of Providencia stuartii (one sensitive, one moderately sensitive and one resistant to chlorhexidine) were induced by cefoxitin, glycine or a lysozyme-tris-EDTA combination, and their susceptibility to chlorhexidine-induced lysis investigated. Maximum lysis of spheroplasts occurred at a low (2.5-5 micrograms/ml) concentration of chlorhexidine and was greatest with the most sensitive strain, Pv2. The possible role of the inner membrane in chlorhexidine resistance is considered in the light of the findings obtained.