Bacteriophage P13234mo-mediated intra- and intergroup transduction of antibiotic resistance among streptococci

Numerous streptococcal strains representing serogroups A, C, and G were tested for transducibility to antibiotic resistance by the temperate Group A streptococcal phage P13234mo. The resistance markers carried by Group A donor strains included the ERL1 factor determining inducible resistance to erythromycin, lincomycin and streptogramin-B type antibiotics as well as chromosomally located mutations for streptomycin and spectinomycin resistance. ERL1, presumably of plasmid nature, was transduced to each of the 36 Group A strains, 10 of the 16 Group C strains, and 1 of the 10 Group G strains tested. Transduction of streptomycin and spectinomycin resistance occurred at lower frequencies than ERL1 transduction, the percentage of transducible Group A strains was lower for these markers than for ERL1, and intergroup transduction was not observed. The effective in-vitro dissemination of resistance factors such as ERL1 by broad host range phages like P13234mo may have some bearing on the marked increase of the incidence of erythromycin and lincomycin resistant streptococci of several serogroups in clinical specimens.