Antimicrobial activity of intravenous quinolones on the intestinal microflora in dogs.

The antimicrobial activity of intravenously given quinolones on the intestinal microflora was unknown and therefore studied in dogs with a surgically isolated loop of the jejunum. Ciprofloxacin, enoxacin and norfloxacin were actively excreted by the intestinal mucosa and achieved therapeutic levels within the lumen of this isolated jejunal loop. Also the total counts of enterococci and Escherichia coli decreased in this loop of the jejunum as well as in the stool. All three quinolones, when given intravenously, decreased the total counts of anaerobic bacteria including Bacteroides fragilis.