Interaction of Escherichia coli and Eimeria brunetti in Chickens

Abstract

Single and dual infections by Escherichia coli (pathogenic or nonpathogenic) and Eimeria brunetti were assessed in 6 groups of 10 chicks each. All 10 chicks dually inoculated with pathogenic E. coli and E. brunetti (Group II) died within 6 days of infection. Of 10 chicks inoculated with nonpathogenic E. coli and E. brunetti (Group IV), only one died. No death occurred in chicks (Group I, III, V) inoculated with E. coli (pathogenic or nonpathogenic) or E. brunetti alone or in control chicks (Group VI). E. coli was isolated from 5 of 10 chicks in Group II, and one of 10 chicks in Group IV. These studies suggested a synergistic relationship between pathogenic E. coli and E. brunetti in causing clinical disease. Nonpathogenic E. coli may also be involved at times, though much less often than pathogenic E. coli. It was also shown that E. coli does not always invade the blood stream, and tissue destruction appears restricted to the gut. Hematologic results suggest that the heterophil leukocytes appeared to respond to sublethal doses of pathogenic E. coli or E. brunetti. However, heterophils failed to give definite response when the chicks were exposed to dual infection with the same dose of pathogenic E. coli and E. brunetti.