Occurrence of transposable trimethoprim resistance in clinical isolates of Escherichia coli devoid of self-transmissible resistance plasmids.

Fifty trimethoprim-resistant clinical isolates of Escherichia coli, devoid of self transmissible trimethoprim resistance plasmids, were examined for the presence of trimethoprim resistance transposons. Trimethoprim resistance was mobilized from 12 strains by transposition onto plasmid RP4. The trimethoprim resistance transposons isolated comprised two groups: those with and without linked streptomycin resistance.