Effect of Antibacterial Agents on the Autoplaque Phenomenon of Pseudomonas Aeruginosa

A survey of 75 cultures of Pseudomonas aeruginosa containing only one discernible phenotype indicated that 68 routinely exhibited spontaneous lysis, resulting in the appearance of turbid erosions or autoplaques (AP+) when grown on a tryptone–glucose agar medium. Single supplements of non-inhibitory levels of chloromycetin, aureomycin, tetracycline, declomycin, and streptomycin increased the degree of lysis of AP+ strains, but were without effect on AP− strains. Enhancement of lysis was also obtained with sulfadiazine, sulfathiazole, sulfamethoxypyridazine, elkosin, gantrisin, and triple sulfa, while little or no effect was observed with sulfamerizine and thiosulfil. On the other hand, low concentrations of either acriflavine or proflavine retarded the rate and degree of lysis, while single supplements of the active antibiotics overcame the suppressive effects of the dyes.