R plasmid with carbadox resistance from Escherichia coli of porcine origin.
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Escherichia coli isolates of porcine fecal origin from a farm where the antibacterial agent carbadox was used were examined for resistance to carbadox (Cdxr). Of 72 strains examined, 24 showed resistance to this drug. All 24 Cdxr strains, except one, were also resistant to tetracycline (Tcr), streptomycin (Smr), spectinomycin (Spcr), sulfadimethoxine (Sur), kanamycin (Kmr), ampicillin (Apcr), or a combination of tetracycline, streptomycin, spectinomycin, sulfadimethoxine, and ampicillin. The Cdxr character was invariably transmissible by conjugation to E. coli K-12 jointly with other drug resistance, with the resistance patterns present in transconjugants being Cdxr Smr Spcr Apcr or Cdxr Smr Spcr Sur Apcr. About 25% of these transconjugants simultaneously lost the resistance to carbadox, streptomycin, spectinomycin, and ampicillin or carbadox, streptomycin, spectinomycin, sulfadimethoxine, and ampicillin or carbadox, streptomycin, spectinomycin, sulfadimethoxine, and ampicillin in the presence of acriflavine. Agarose gel electrophoretic analysis of deoxyribonucleic acid from a transconjugant showed a single plasmid deoxyribonucleic acid molecule with a molecular weight of about 28 x 10(6), which was capable of transforming E. coli C to Cdxr Smr Spcr Apcr. This resistance was transmissible by conjugation as a unit to other K-12 strains. These results confirmed the presence of an R plasmid specifying the Cdxr character in the host strain. (+info)
Mutagenicity of quindoxin, its metabolites, and two substituted quinoxaline-di-N-oxides.
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The quinoxaline-di-N-oxides carbadox, olaquindox, and quindoxin, which are potent antibacterial agents, were tested for mutagenicity in the Salmonella microsomal system. They all induced base pair substitutions and frameshift mutations in Salmonella, and occurred independently of the presence of a rat liver microsomal fraction in the test system. Mutagenicity was dependent on the presence of their N-oxide groups, since quinoxaline, a completely reduced derivative of quindoxin, was not mutagenic, whereas the partially reduced quinoxaline-N-oxide exhibited a lower mutagenic activity than quindoxin. recA and uvrB Salmonella were found to be more susceptible to mutagenic quinoxaline derivatives than wild-type strains. The mutagenicity of quinoxaline-di-N-oxides was enhanced under anaerobic incubation as was the antibacterial activity. These results suggest that both the antibacterial and mutagenic activity of quinoxaline-di-N-oxides depend upon the same bacterial activation mechanism. (+info)
Effect of carbadox and various dietary copper levels for weanling swine.
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Two experiments were conducted to evaluate the responses to carbadox and Cu additions in the postweaning diet of swine. The first trial contained 470 pigs in five replicates in a 2 X 5 factorial arrangement in a randomized complete block design. Weanling pigs 4-wk of age were fed diets containing 0 or 55 ppm carbadox and 0, 125, 375 or 500 ppm Cu for a 5-wk period. Copper levels of 125 and 250 ppm resulted in improved pig gains and feed intakes, but at 500 ppm, gains and feed intake declined. Carbadox resulted in enhanced gain and feed performance throughout the trial, but most notably during the initial 2-wk period. Copper improved performance measurements only during the latter 3-wk and for the overall period. There was an additive performance response when carbadox and Cu (125 ppm) were provided in combination. When carbadox was not provided, growth responses increased to the 250 ppm dietary Cu level. Liver, kidney cortex, heart and plasma Cu concentrations increased quadratically as dietary Cu levels increased, with the greatest change occurring between 250 and 500 ppm dietary Cu levels. A N and Cu balance trial in group feeding conditions involving 65 pigs was conducted in two replicates of a 2 X 2 X 5 factorial arrangement of a split-block design. Pigs were ad libitum fed diets with or without 250 ppm Cu and carbadox at 0 or 55 ppm for a 5-wk period. A fifth treatment group fed the 250 ppm Cu plus carbadox diet was pair-fed to the pigs fed the basal treatment. Growth rate and N retention increased when carbadox, but not when Cu was provided. When carbadox and Cu were provided in combination, either ad libitum or pair-fed, N retention was greater than when the basal diet was fed. This response was attributed to the carbadox addition. The carbadox addition reduced Cu retention and liver Cu concentrations. (+info)
Effect of a synthetic antimicrobial agent on the rates of synthesis and degradation of liver and skeletal muscle proteins in growing rats.
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A double isotope technique was used to evaluate the effects of a synthetic antimicrobial compound (carbadox) upon the synthesis and degradation of rat liver and muscle proteins. Trials 1 and 2 used, respectively, 20 and 12 male Sprague-Dawley rats with average initial weights of 75 and 81 g. A 16% crude protein corn-soybean diet without or with carbadox (55 ppm) was fed. Rats were randomly assigned to diets which were fed 10 days prior to the initial isotope (14C-lysine) injection. The second isotope injection (3H-lysine) was made 3 days after the 14C-lysine injection in trial 1, 6 days in trial 2. Four hours after the second injection, the rats were killed and the right and left quadriceps and a sample of liver were removed. Total protein from the right quadriceps was prepared via a boiling trichloroacetic acid (TCA) extraction procedure. The left quadriceps was separated into myofibrillar and sarcoplasmic protein fractions via a KCl salt gradient. In both trials, gains were similar across treatments, but markedly reduced during the injection periods. Gain/feed prior to injection was greater (P less than 0.05) for carbadox-fed rats. In both trials right quadriceps 3H-incorporation (expressed as 3H cpm/mg protein) and relative degradation (3H cpm/14C cpm) were not affected by dietary carbadox. The sarcoplasmic and myofibrillar protein fractions were also not significantly affected. However, in both trials liver protein 3H-incorporation was enhanced (P less than 0.025) by carbadox, while liver protein degradation was affected (P less than 0.001) only in trial 2. (+info)
Effects of carbadox, copper, or Yucca shidigera extract on growth performance and visceral weight of young pigs.
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Two identical trials, each with 128 crossbred weanling barrows (6.8 +/- .2 and 7.6 +/- .2 kg for Trials 1 and 2, respectively), were conducted. In each trial, pigs were allowed to consume ad libitum a 16% CP corn-soybean meal basal diet (B), B + 55 ppm of carbadox, B + 250 ppm of copper (Cu), or B + 125 ppm of Yucca shidigera extract for 56 d (four pens/diet; eight pigs/pen). At d 56 of the test, eight pigs/diet (two pigs/pen) were slaughtered for carcass and viscera measurements. Data of carbadox treatment in Trial 1 are excluded from this paper because of an error in mixing of the diet. In Trial 1, during the test period from d 0 to 28, pigs fed Cu had greater (P < .05) ADG and ADFI than those fed B, whereas pigs fed yucca extract had higher ADFI (P < .05) but similar ADG (P > .05) compared with those fed B. During the period from 29 to 56 d, ADG was similar among pigs fed different diets (P > .05) but ADFI was affected (P < .05) by diet (yucca extract > Cu > B). No differences (P > .05) among diets were detected for gain/feed (G/F) and visceral weights expressed as a percentage of slaughter BW. In Trial 2, during the first 28 d, the ADG, ADFI, and G/F responses of pigs to Cu, yucca extract, and B were similar to those observed in Trial 1.(ABSTRACT TRUNCATED AT 250 WORDS) (+info)
Incidence of antibiotic resistance in fecal Escherichia coli isolated from commercial swine farms.
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Sows and pigs from 10 commercial swine farms were sampled to determine patterns of resistance of fecal Escherichia coli to five commonly used antibiotics. Before testing, farms were categorized as high or low antibiotic use based on interviews with the respective producers. On each farm, fecal swabs were obtained from five sows at 7 d postpartum and from five pigs from each sow at 7, 35, and 63 d of age. A total of 6,296 E. coli isolates from 750 pig fecal samples and a total of 462 E. coli isolates from 50 sow fecal samples were tested against apramycin, carbadox, gentamicin, neomycin, and oxytetracycline using a standardized disk diffusion test. Percentage of resistant organisms was compared between pigs at the various stages of growth, between sows and their respective pigs, and between farms of high and low antibiotic use. Incidence of resistance was greater (P < .05) in pigs at 35 or 63 d of age compared with 7 d of age for most antibiotics, and patterns differed between high-use and low-use farms. Resistance differed (P < .05) among E. coli from pigs compared to their respective sows for apramycin and carbadox on low-use farms, whereas incidence of resistance on high-use farms differed (P < .05) between sows and pigs for apramycin and oxytetracycline. These data indicate that patterns of antibiotic resistance are dependent on age of pig and level of antibiotic use. (+info)