The effect of apramycin on colonization of pathogenic Escherichia coli in the intestinal tract of chicks

The purpose of the present study was to examine the effect of apramycin sul phate on the colonization of pathogenic E, coli in the intestines of chicks . Apramycin treatment (0.5g/l in the drinking water) of 3-to 5-week-old Leg horn chicks for 24 or 48 hours resulted in a reduction, to an undetectable level, in the number of coliforms in the digestive tract for at least the f irst 24 h, Per os inoculation of E, coli (O2:K1) after 24 to 48 h of treatm ent resulted in a significant decrease in colony forming units (cfu) in the digestive tract of the treated chicks. Food deprivation from the time of i noculation did not significantly change the results. However, food and wate r deprivation caused bacteraemia in a number of the control chicks but not in the treated chicks. Comparison of the level of protection between Leghor n and broiler (Anak strain) chicks revealed that there was a significantly higher (P<0.05) level of bacteraemia in the broiler than in the Leghorn chi cks. Chicks treated with 0.25 g/l or 0.125 g/l apramycin for 24 or 48 h bef ore E, coli inoculation showed significantly lower cfu in the colon and cae cum than untreated control chicks, but significantly higher cfu were found in the colon than in chicks treated with 0.5 g/l apramycin, Although in vit ro preincubation of apramycin with ileum cells did not decrease the percent age of cells to which the bacteria adhered, the number of bacteria adhered per cell decreased significantly. Taken together, our in vitro and in vivo results show that apramycin is effective against E, coli by preventing colo nization of the gut by the bacteria, which could lead to a reduction of col ibacillosis in poultry.