Effects of Antibiotics in Animal Feed on the Antibiotic Resistance of the Gram Positive Bacterial Flora of Animals and Man
The use of antibiotics in the raising of farm animals has become an area of considerable controversy in recent years. There have been numerous allegations that this practice, particularly the incorporation of subtherapeutic levels of antibiotics into feed for purposes of growth promotion, is contributing to the increasing incidence of drug resistance in bacterial pathogens that infect man. It has been suggested that the selective pressure exerted upon the bacterial flora of animals by these antibiotics gives rise to large populations of resistant microorganisms. The organisms are then postulated to enter the human population, either through agricultural and meat processing workers, or via the food chain, as a result of contamination of meat products. Once in contact with man, the resistant bacteria could presumably cause disease directly, or transfer their resistance to organisms more pathogenic for humans. Although there is documentation of specific instances of human disease caused by resistant organisms from the farm, the extent to which this occurs has been difficult to assess. Representatives of the drug and animal raising industries have argued that therapeutic use of antibiotics in the treatment of human diseases has a much larger effect on the human resistance problem than agricultural use of antimicrobials. In fact, proponents of both points of view have used the same experimental data to support their particular position on several occasions. Virtually all of the research done in this area has been focused on the gram negative bacteria, particularly the members of the Enterobacteriaceae.
KeywordsBacterial Flora Positive Bacterium Resistant Organism Macrolide Resistance Plasmid Profile
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