Effect of cefditoren pivoxil on intestinal bacterial flora

The effect of cefditoren pivoxil, a new oral cephem antibiotic, on intestinal bacterial flora was studied in tetra-contaminated mice and pediatric patients. Cefditoren pivoxil in the granule form was administered in a dose of 15 mg/kg once a day 5 consecutive days to mice infected with Escherichia coli, Enterococcus faecalis, Bacteroides fragilis and Bifidobacterium breve. The viable fecal bacterial cell count of each of these 4 species was slightly reduced 5 days after starting the drug. Four children (2 males and 2 females, weighing 15.0 to 24.0 kg) with bacterial infections were entered into this pediatric study. Their ages ranged from 2 years 6 months to 8 years 6 month. Cefditoren pivoxil (granules) was administered in doses between 3.33 and 5.56 mg/kg, 3 times a day for 5 to 19 days. Some variations were seen in the fecal bacterial flora of these patients during the period of drug administration. Cell counts of primary aerobes, anaerobes and total anaerobic cells decreased markedly in one patient, but in the remaining three patients the total number of aerobic and anaerobic cells did not change greatly, except for a tendency for the cell counts of Enterobacteriaceae to decrease. Glucose-nonfermentating gram-negative rods tended to increase transiently, but did not become predominant during the period of cefditoren pivoxil administration. Candida became predominant in one patient in whom the other bacteria had markedly decreased. In the other three patients, however, Candida did not become predominant, although it did tend to increase in two of them during or after treatment. Cefditoren pivoxil was not detected in the feces of any of the patients, but cefditoren, the active form of cefditoren pivoxil, was detected in concentrations ranging from 3.78 to 1, 389 μg/g in the feces of three patients during treatment. A high concentration of cefditoren (1, 172~1, 389μg/g) was detected in the feces of the 8-year-6-month old patient. In this patient primary aerobes and anaerobes decreased markedly. Intestinal bacteria that produce β-lactamase were present in the feces of all the patients. Based on these results, cefditoren pivoxil had relatively little effect on intestinal bacterial flora. Because of individual differences, however, the drug may excreted in the feces in high concentrations, and this would result in changes in intestinal bacterial flora. Consequently, attention must be paid to fecal drug concentrations.