Spectinomycin and Rat Large Bowel Microflora Associated Characteristics

Three groups of adult male rats were fed chow supplemented with spectinomycin (SPC 0, 0.1 and 10 ppm, respectively). After 42 days there was no difference in the mean weight gain of the three groups. SPC did not change the levels of Escherichia coli in the rats’ ceca. The distribution of resistance to SPC among E. coli from the three groups was not altered by SPC in the diet. SPC had no significant effect on pH, ammonia levels and stool moisture. It had no impact on the total short chain fatty acid production though the relative abundance of individual analytes was changed. Sterol and bile acid metabolism were unaffected. Comparison of cellular fatty acid (CFA) profiles showed small but measurable differences between the three groups. The no-drug controls and rats in the 0.1 ppm group had highly similar CFA profiles while the profile of the 10 ppm group was more distinct, suggesting a possible dose-dependent response to SPC. Keywords: spectinomycin, cellular fatty acids, short chain fatty acids, bile acids, neutral sterols, rats microflora, resistance, bowel.