Effect of amoxicillin (Clamoxyl) on the colonic microbiota during and after antibiotic treatment. (A) Concentrations of lactobacilli, enterobacteria, and enterococci in colonic contents of saline-treated rats (closed diamonds) and amoxicillin-treated (PND7 to PND18) rats (open squares) at PNDs 15, 21, 36, 42, and 56 (the results of one of five representative experiments are presented; n = 5 to 8 per group). (B) Concentrations of lactobacilli, enterobacteria, and enterococci at PND25 in the colonic contents of saline-treated rats (gray bars) and amoxicillin-treated rats (PND7 to PND25) (white bars) (n = 8 per group; the results of one of two representative experiments are represented). Data are expressed as log CFU/g of luminal content (mean ± standard error of the mean). *, significant differences between saline- and amoxicillin-treated groups (P < 0.05). The detection limit was 3 log CFU/g intestinal content.