Antibiotic Resistance in Soil Bacteria Associated with Cattle Manure.

Soil bacteria are believed to be a significant source of new resistance mechanisms to clinically used antibiotics. Anthropogenic additions of antibiotics into the soil environment may increase the prevalence of resistance among soil bacteria. The livestock industry may be such a source of antibiotics. In this study soil samples from a cattle feedlot, a field with annual applications of cattle manure, and a field without a history of manure applications were tested for antibiotic resistance. The populations of bacteria resistant to tetracycline, erythromycin, ampicillin, and vancomycin were determined using a serial dilution technique. Specific resistance mechanisms were also tested for from each of the soil samples as well from resistant isolates using PCR. Preliminary results show resistance to all of the antibiotics in all three soils, with the lowest levels of resistance in the unmanured soil and highest in the feedlot soil.