Effect of a single injection of lincomycin, spectinomycin, and linco-spectin on early chick mortality caused by Escherichia coli and Staphylococcus aureus.

The efficacies of lincomycin (L) and spectinomycin (S), alone and in various combinations (L/S), were determined against Escherichia coli (EC) and Staphylococcus aureus (SA) of avian origin, both in vitro and in vivo. L contributed significantly to L/S activity against SA, while S contributed significantly to L/S activity against EC, and L/S (2.5 mg L + 5.0 mg S) was more effective than either L or S against SA and EC. The suggested optimum dose for controlling early chick mortality caused by SA and EC is 2.5/5.0 mg of L/S per chick.