Evaluation of the resistance induction in enteric flora in children caused by oral ampicillin plus sulbactam

To evaluate the effect on bacterial resistance of a beta-lactamase inhibitor, resistance patterns of predominant bacteria in enteric flora were evaluated before and after a 7-day course of oral ampicillin (100 mg/kg/days, qid, in 16 patients) and ampicillin-sulbactam (50 mg/kg/day of ampicillin, bd, in 32 patients) therapy. Ampicillin and ampicillin-sulbactam MICs for Escherichia coli, the predominant bacteria in all cases, and resistance rates of E. coli species to both antibiotics were 51.20 +/- 13.80 mg/L, 87.5% and 4.84 +/- 2.11 mg/L, 21% before the treatment respectively. Post-treatment MICs and resistance rates were 106.51 +/- 14.05 mg/L, 100% and 15.89 +/- 5.76 mg/L, 37.5% respectively, indicating a significant increase in MICs of both antibiotics (P < 0.05), being more prominent in the case of ampicillin-sulbactam (about four-fold). We concluded that oral ampicillin-sulbactam could also decrease the susceptibility of the enteric flora to ampicillin.