Infectious drug resistance among clinically isolated Escherichia coli.

Of 398 strains of clinically isolated Escherichia coli from three Birmingham, Alabama, hospitals, 38% were found to be resistant to one or more drugs tested. Fifty-seven per cent of the resistant strains transferred all or a part of their resistance pattern to sensitive cells during mixed cultivation. Of the 152 resistant strains, 29.1% were singly resistant, and 70.5% were resistant to more than one drug. Of the multiply resistant strains, 61% transferred all or a part of their pattern. Strains isolated from Veterans Hospital patients demonstrated higher percentages of resistance than strains isolated from Children's Hospital patients. An extremely low incidence of infective drug resistance was noted among E. coli isolated from the stools of healthy hospital employees.