Occurrence of antibiotic-resistant Escherichia coli isolated from environmental samples

A total of 311 E. coli strains were isolated from Sauce Chico River waters, and from Bahía Blanca estuary waters and sediments, Argentina. Resistance of organisms to seven antimicrobial drugs was assessed. Resistance was most common to streptomycin, sulphamide and tetracycline. The principal source of the antimicrobial drug-resistant bacteria was non-treated sewage. It is considered that the presence of antibiotic-resistant E. coli in the environment is a great problem, especially those carrying plasmids which might determine this capability (R factors). These plasmids can be transferred from resistant donors to certain sensitive recipients. It is well known that transference and selection may be the source of antibiotic resistance genes in bacterial population. On the other hand, the incidence of such tolerant bacteria is a good indicator of the environmental consequence of the antibiotic use for unnecessary purposes in human and animal medicine.