Genetic localization of the resistance to fosfomycin.

The possible existence of a transferable resistance to fosfomycin was studied in 50 strains of enterobacteria that were isolated in our hospital and which showed a resistance to fosfomycin of more than 256 mug/ml. E. coli K12 E711 was used as a receptor strain in the conjugation -- the times of conjugation were 20 min and 18 h. We found a transferable resistance in 28% of the strains. In all but one of the cases, only the resistance to fosfomycin was transferred. The recombinant which received the resistance to fosfomycin together with three other resistances was used as the donor for the transduction with the phage P1Kc to the receptor strain which was E. coli UTH 1038. A study was carried out on the influence of the radiation of the transducing phages with ultraviolet light on the frequency of transduction. The findings demonstrated a linear decrease in the frequency in proportion to the increase in the time of radiation.