Transfer of drug resistance factor in Shigella sonnei isolated in Iran.

The pattern of drug resistance and incidence of R-factors were studied in Shigella sonnei strains isolated in Iran. Eighty-nine out of 172 strains (51.7%) were resistant to one or more drugs and multiple drug resistance was more common than single drug resistance. The most predominant pattern of resistance observed was (Tc, Cm, Sm, Su). By mixed cultivation, 85.7% of Shigella sonnei resistant strains isolated on the Central Plateau and 100% of the strains from the caspian littoral transferred at least a part of their resistance pattern to sensitive E. coli K12 F- (gamma). In this experiment, 67.1% of our resistant and 17% of our sensitive strains had colicinogenic properties. No such difference could be observed between R+ and sensitive strains isolated in the Caspian littoral.