Antimicrobial alternatives for calf diarrhea: sera trace element responses to Escherichia coli-, deferoxamine-, or gallium-induced diarrhea

Aseptic and septic inflammatory diseases often are associated with marked changes in tissue and sera trace element kinetics. Iron and zinc sequestration by the host may serve as a protective effect against microbial proliferation, but may deprive host tissues of these necessary elements as well. Conversely, systemic iron administration has been shown to increase susceptibility to, and severity of, infectious diseases, although deficient iron stores may be repleted. Escherichia coli enteritis in calves provides a model wherein the effects of enteric iron antagonism and parenteral iron supplementation may be studied simultaneously. Male calves (n = 12) were given (IM injection) 300 mg of iron-dextran after base-line blood samples were obtained, then the calves were allotted to 4 groups (each of 3 calves): group 1 (control)--orally given nonpathogenic E coli; group 2--orally given enterotoxigenic B44 E coli; group 3--orally given deferoxamine (50 mg/kg, twice a day); group 4--orally given gallium (4 mg/kg; twice a day). Calves were studied for 8 days; blood samples were obtained each day (day 1 through day 8) for hematologic and serum biochemical analyses. There were significant increases in serum iron concentration and % saturation in all calves within 24 hours of iron-dextran administration, which returned to base-line values in all but group 4 (given gallium) within 3 days. In the exceptional group (4), total iron-binding capacity decreased with time, as in the other groups, but serum iron concentration remained significantly increased, implying gallium interference with systemic iron assimilation.(ABSTRACT TRUNCATED AT 250 WORDS)