Survey for Transmissible R Plasmids in Salmonella Isolated from Healthy Tokyoites During from the 6-Year Period from 1976 through 1981

Abstract

A total of 3, 578 of Salmonella isolated from healthy Tokyoites during the 6-year period from 1976 through 1981 were tested for antibiotic resistance.
We tested for transmissible R plasmids in 746 strains of those which offered resistance to antibiotics. The results obtaind are summarized as follows.
Transmissible R plasmids appeared in 38% of resistant strains, but the frequency of isolation of Salmonella with transmissible R plasmids tended to decrease year by year.
The frequency of strains with resistance to Tetracycline, Kanamycin, Ampicillin or Chloramphenicol mediated by R plasmids were high at about 70% for each, wherease those with resistance to Streptomycin or Sulphafurazole were low at about 40%.
Transmissible R plasmids were seen with high frequency in resistant strains of S. enteritidis (100%), S. manhattan (86.5%) and S. panama (75.9%). In contrast, they were seen with low frequency in the resistant strains of S. london (3.8%), S. tennessee (11.1%) and S. give (15.0%).
The demonstrated resistant patterns with R plasmids were characterized by serovars. The patterns of Tetracycline and Kanamycin in S. panama, Streptomycin, Tetracycline, Kanamycin and Ampicillin in S. manhattan and Tetracycline, Chloramphencol and Sulphafurazole in S. litchfield were few derived from other serovars.
The fi (+) type of R plasmids were found in less than one-fourth of all the R plasmids. However, fi (+) type tended to increase in number, year by year.