Continuous Non-Therapeutic Use of Antibacterial Drugs in Feed and Drug Resistance of the Gram-Negative Enteric Florae of Food-Producing Animals

Abstract

A number of antibacterial drugs are routinely included on a continuous basis in the feed of animals used for the production of food. These drugs, most of which are also utilized in human medicine, are added to animal feed for therapeutic, prophylactic, and various production purposes. The agricultural applications of medically important drugs have been questioned because of the direct selegctive effects of the drugs favoring an increased occurrence of drug resistance in pathogens of animal origin. Furthermore, because of the transmissibility of resistance in gram-negative enteric organisms, resistant enteric organisms normally considered nonpathogenic may provide a reservoir of resistance for both human and animal pathogens.Reports have documented the prevalence of resistance among specific members of the Enterobacteriaceae obtained from farm animals fed various antibacterial drugs (3,5,7,8,(10)(11)(12)(13)(14)(15)

Trends in Human Fecal Carriage of Extended-Spectrum β-Lactamases in the Community: Toward the Globalization of CTX-M

“…The rapid and wide dissemination of this gene in cattle as well as in food, pets, and environments (138)(139)(140)(141)(142) is also paralleled by recent observations made for CTX-M (143). The commu-nity certainly appears to be the major reservoir of CTX-M-type ESBL (Fig.…”

Human Therapeutic and Agricultural Uses of Antibacterial Drugs and Resistance of the Enteric Flora of Humans

“…Neomycin resistance was absent among isolates of group 5 and ranged from 5 to 13% in the remaining groups. Sulfamethazine resistance was the most frequent for groups 1 and 2 (43 and 41%) as compared to the resistance for the remaining three groups (between 7 and 10% The presence of ampicillin-resistant organisms in farm animals (7) was reflected in the appearance of ampicillin-resistant organisms in the farm worker and resident. Although ampicillin was not used on the farm, the use of other antibacterial drugs in animal feed appeared to result in the emergence of ampicillinresistant organisms (7).…”

“…An investigation relating to this question was conducted to determine whether or not enteric florae continuously exposed to antibacterial drugs and composed largely of antibiotic-resistant organisms influenced epidemiologically associated enteric florae unexposed to antibacterial drugs. A previous paper reported the high proportions of antibiotic-resistant, gram-negative enteric organisms in fecal samples from Illinois farm animals given feeds containing antibacterial drugs (7). This paper reports the proportions of resist- ' (BBL) was used for all broth cultures.…”

“…This practice has been questioned because it might create conditions detrimental to animal and human health. It has been established that the enteric florae of farm animals are largely composed of drug-resistant organisms as a result of the continuous exposure to antibacterial agents (5,(7)(8)(9)(10). Due to the transmissible nature of drug resistance in gramnegative enteric organisms, it has been postulated that the resident animal flora may comprise a reservoir of resistance for animal and human pathogens.…”

“…The procedure used to determine the relative proportions of oxytetracycline-, dihydrostreptomycin-, or ampicillin-resistant organisms has been described in detail (7). This procedure consisted of plating saline dilutions of a fecal suspension on MacConkey agar and MacConkey agar containing antibiotic.…”