Role of intestinal excretion in the effect of subcutaneously administered sedecamycin on cecal infection caused by Treponema hyodysenteriae in mice

Macrolide antibiotics in food-animal health

Several 14- and 16-membered-ring macrolide antibiotics have acquired important roles in the modern production of food animals. Macrolide antibiotics exhibit many similar antimicrobial properties whether used in veterinary or human medicine. In addition to their direct inhibitory action on micro-organisms, macrolides exert a variety of subinhibitory concentration (sub-MIC) effects that are being increasingly recognised as important factors in the explanation of therapeutic results. Macrolides achieve wide tissue distribution and high intracellular concentrations that contribute prominently to their efficacy. Another important factor governing efficacy is the complex interaction between macrolides, micro-organisms, and phagocytes that may enable the host defence system to enhance the antibiotic's inhibitory action. A potential role for macrolides in modulating inflammatory processes has also been recognised. In both sub-MIC effects and interactions with the host immune system, different macrolides exert different responses that may reinforce or oppose each other. This complexity of responses requires additional studies in appropriate disease states and animal species in order to elucidate a more comprehensive understanding and explanation of in vivo outcomes.

Sensitivity of strains of Serpulina hyodysenteriae isolated in Hungary to chemotherapeutic drugs

The sensitivity of 332 strains of Serpulina hyodysenteriae isolated in Hungary between 1978 and 1992 was tested against seven chemotherapeutic drugs frequently used for the treatment of swine dysentery, and the changes in the patterns of resistance were also monitored. All the strains remained sensitive to carbadox, with minimum inhibitory concentrations (MIC) of only 0.05 to 0.40 microgram/ml at present. The susceptibility of the strains to dimetridazole has gradually decreased, but about half of the strains are still sensitive, with large numbers of "moderately sensitive' strains; the MIC values varied within wide limits (0.1 to 50 micrograms/ml). Most of the strains were resistant to tylosin, with MIC values from 0.1 to 100 micrograms/ml. The number of strains resistant to lincomycin has gradually increased, but about half of the strains remain sensitive; the MIC values ranged from 0.2 to 100 micrograms/ml. Recently, tiamulin has proved the most effective antibiotic, but some resistant strains have already emerged (MIC values 0.05 to 50 micrograms/ml). Monensin was good for the prevention of swine dysentery, but resistance may evolve quickly; the MIC values ranged from 0.4 to 25 micrograms/ml. For sedecamycin, the MIC values (6.25 to 100 micrograms/ml) were much higher than expected.

Excretion of ciprofloxacin into the large bowel of the rabbit

The intestinal elimination of ciprofloxacin in the large bowel was studied in a rabbit model. Segments from the cecum, colon, and sigmoid colon along with their intact blood vessels were isolated and perfused, and their contents were collected over a 90-min period following the administration of a single parenteral dose of 27 mg of ciprofloxacin per kg of body weight. The elimination rates of ciprofloxacin were 0.126 +/- 0.084 micrograms.min-1.cm-2 in the cecum and 0.264 +/- 0.126, 0.11 +/- 0.07, and 0.21 +/- 0.141 micrograms.min-1.cm-2 in the proximal colon, distal colon, and sigmoid colon, respectively. The calculated fraction of ciprofloxacin eliminated in the large bowel was 3% of the parenteral dose administered. The elimination pattern of ciprofloxacin in the large bowel may explain the unusual activity of this fluoroquinolone in modifying the colonic flora.

Intestinal elimination of ciprofloxacin in rabbits

The intestinal transepithelial elimination of ciprofloxacin was studied in a rabbit model. Jejunal, ileal, and cecal segments along with their intact blood vessels were isolated and perfused, and their contents were collected over a 120-min period following administration of a single parenteral dose of 27 mg of ciprofloxacin per kg of body weight. The intestinal elimination rates of ciprofloxacin were 0.126 +/- 0.084, 0.235 +/- 0.22, and 0.11 +/- 0.084 micrograms.min-1.cm-2 for the jejunal, ileal, and cecal segments, respectively. The calculated fractions of ciprofloxacin eliminated were 3.3 mg from the jejunum and 13.8 mg from the ileum, representing 19% of the administered dose. Additional amounts of 2.5 to 3.7 mg or 4.9 to 7.3% of the administered dose were eliminated from the cecum. Elimination was probably not due to a passive diffusion process but rather due to an active transepithelial transport. This intestinal elimination pattern of ciprofloxacin may explain the unusual activity of the fluoroquinolones in modifying the intestinal flora.