Effect of Low Concentrations of Dihydrostreptomycin on Drug Resistance in Enteric Bacteria

Beagle dogs were fed a diet containing 0, 2, or 10 μg of dihydrostreptomycin (DSM) per g of feed. The 2-μg/g level was selected to represent a residue level of the antibiotic. In both treatment groups, medicated feed resulted in a shift from a predominantly streptomycin (SM)-susceptible coliform fecal population to an SM-resistant population. The proportion of resistant organisms was significant ( P Escherichia coli K-12 recipients.