R-plasmid study of an outbreak caused by multiresistant strains of Salmonella panama.

A salmonella panama outbreak was observed in the months May through July, 1979, in the newborn and intensive wards of a paediatric hospital. The isolates proved to be multiresistant to antibiotics. To clarify the presumed R-plasmid nature of the multiresistance, the transfer of the resistance to five antibiotics, viz. ampicillin, chloramphenicol, streptomycin, kanamycin and tetracycline, was studied. Escherichia cole K12 Nalr, the strain used as recipient, acquired resistance simultaneously to four antibiotics, viz. ampicillin, chloramphenicol, streptomycin and kanamycin. The minimum inhibitory concentration for the transconjugants agreed well with that of the original S. panama strain. Resistant and multiresistant E. coli. strains not belonging to serogroups associated with infantile enteritis were isolated from the intestinal flora of several patients and symptomless carriers. Elimination of the transmissible multiresistance was observed in 0.15-1.1% of the strains.