Protective effect of pyocin against lethal Pseudomonas aeruginosa infections in mice.

Abstract

Organisms. The pyocin-producing strain of P. aeruginosa (P 10) and the susceptible indicator strains 12, 13, 4, and '6 were described by Gillies and Govan [2]. Indicator strain IB, which is resistant to the pyocin of strain P 10, was described by Tagg and Mushin [3]. All of these strains were kindly supplied by Dr. Rose Mushin, Kimron Veterinary Institute, Beit Dagon, Israel. Pyocin production. A modification of the method of Higerd et al. [4] was used. A mitomycin C-induced culture of P. aeruginosa (strain P 10) was centrifuged at 13,000 g for 30 min at 4 C. The supernatant fluid was lyophilized, and the dry residue was redissolved in Tris-chloride buffer (pH 7.5) to one-tenth of the original volume. The concentrated material was dialyzed against Tris-chloride buffer at 4 C for 48 hr and then sterilized by filtration (Millipore membrane, 0.22 Ctm). The sterile pyocin retained its activity for two to three weeks if stored at 4 C. Pyocin activity was assayed according to Higerd et al. [4] on each new batch prepared. The susceptibility of the series of indicator strains was recorded.