EFFECT OF INTRAVENOUS COLISTIN ADMINISTRATION ON Escherichia coli LIPOSACCHARIDE-INDUCED ENDOTOXEMIA IN SHEEP.

The effects of intravenous colistin along with lipopolysaccharide administration in sheep were studied. Twenty clinically healthy Iranian fat-tailed sheep were allocated into four equal groups: negative and positive controls, colistin at 12,000 U/kg and colistin at 24,000 U/kg. Endotoxemia was induced by administration of lipopolysaccharide of Escherichia coli serotype O55:B5 at 0.5 μg/kg, intravenously in all experimental groups, except negative control. Clinical signs and haptoglobin (Hp), tumor necrosis factor-α (TNF-α), blood lactate, blood urea nitrogen (BUN) and creatinine were determined. TNF-α was significantly different between the positive control and the colistin groups, but, there were no significant differences between colistin 12,000 IU/kg and colistin 24,000 IU/Kg groups. Serum concentrations of Hp at different times in colistin groups were significantly lower than positive control group and colistin 12,000 IU/kg had a better effect on the reduction of serum Hp. Colistin 12,000 IU/kg was able to retain levels of blood lactate relative to the colistin 24,000 IU/kg group. Serum concentration of BUN was markedly increased after E. coli-induced endotoxemia in all experimental groups, but they had no consistent pattern in all experimental groups at different times. Based on the results, it was concluded that colistin could be used as an anti-endotoxic drug against the E. coliinduced endotoxemia in sheep. [ABSTRACT FROM AUTHOR]