Antibiotic and metal resistance of Escherichia isolates from different environmental sources

The resistance of 286 strains of E.coli isolated from surface waters, ground water and breeding effluents, to five antibiotics and three heavy metals, was compared with that of 104 E.coli stains of human origin. the highest percentage of resistance among the environmental isolates was found in the strains obtained from river water. The percentage of resistance to different antibiotics was variable and found to be highest with respect to ampicillin, streptomycin and tetracycline. Multiresistance phenomena was observed primarily with the isolates from surface waters and those of human origin. Correlation analysis revealed that the resistance patterns of E.coli isolates from water environments are related, but only the antibiotic resistance patterns of river isolates was correlated with that of the strains of human origin. No correlation could be detected with respect to the antibiotic resistance patterns of environmental strains and strains isolatedfrom breeding effluents.Antibiotic and metal resistance were transferred to the recipient E.coli CSH26 Nal strain by eleven of twelve strains tested: the transfer took place with the transconiugant donor ratio varying from 10-1 to 10-4, the ratio being higher for the metals than for the antibiotics.