[Antibiotic-resistant coliforms in a purification station on a pig-breeding farm]

The survival of antibiotic-resistant enteric bacteria in the effluent treatment plant of a pig farm was studied by quantitative determinations of resistant and sensitive populations at different sites of the effluent purification process. The effluent treatment system, combining storage and aeration tanks, reduced the concentration of enteric organisms in the output of the plant to about one-tenth of the concentration found in the incoming untreated slurry. This reduction occurred mainly at the level of the aerated tank and was observed for the total population of enteric organisms as well as for the various populations resistant to ampicillin, chloramphenicol, kanamycin, streptomycin and tetracycline respectively. Moreover, no particular sequence of resistances seems to have been selected during treatment. Storage and aeration of pig slurry before disposal reduces the risk of dissemination of antibiotic-resistant bacteria of animal origin in the environment, as compared to the frequent direct spreading of untreated effluents.