Y 33, TTGE bands corresponding to Rf of B. get BIBS39 adolescentis were detected in 83 of subjects, Rf of B. longum in 55 of subjects, Rf of B. pseudocatenulatum/B. catenulatum group in 55 of subjects, Rf of B. bifidum in 22 of subjects, Rf of B. dentium in 11 of subjects and those of B. breve in 17 of subjects. At day 64 (2.260.2 species per sample), only few differences were still get 4EGI-1 observed in species identification. Since Bifidobacterium bands were all identified, the Jaccard’s similarity coefficient equivalent to Dice’s was calculated withFigure 4. TTGE profiles representing the bifidobacterial diversity of fecal samples from two healthy volunteers (A and B) before and after AMC exposure. 1:day-12; 2:day-6; 3:day 0; 4:day 5; 5:day 8; 6:day 12; 7:day 19; 8:day 26; 9:day 33; 10:day 64. a, b, d, e, f, a9: B. adolescentis; c, g: B. bifidum; b9: B. pseudocatenulatum; c9: B. longum; d9: B. dentium; e9: B. breve; f9: B. pseudolongum; g9: B. animalis subsp. lactis. doi:10.1371/journal.pone.0050257.gBifidobacterium Monitoring after AMC ExposureFigure 5. Mean similarity coefficients of specific Bifidobacterium TTGE profiles of samples collected before and after AMC exposure (day0 ay5) and calculated according to the reference period (day-12 day-6 day 0; n = 17). doi:10.1371/journal.pone.0050257.gspecies as characters and showed that changes concerned species and not only strains within a species (Fig. 7).DiscussionA previous study on the same 18 volunteers focusing only on bacterial resistance showed that the administration of AMC increased the amoxicillin resistant Escherichia coli and enterococci.From a baseline of less than 1 , more than 30 of resistant E. coli and 6 of resistant enterococci were observed and progressively decreased to baseline at day 12 [31]. In the present study, the impact of a 5-day AMC treatment was quantitatively and qualitatively assessed at short- and long-term on total microbiota and on fecal Bifidobacterium species in 18 healthy men. Bifidobacteria were detected in all fecal microbiota from the 18 subjects (100 ) before exposure to AMC. The counts of totalFigure 6. Occurence rate of Bifidobacterium species monitored before and after AMC exposure (day0 ay5); n = 18 adults. doi:10.1371/journal.pone.0050257.gBifidobacterium Monitoring after AMC ExposureFigure 7. Change of species after the AMC exposure. doi:10.1371/journal.pone.0050257.gbacteria and total bifidobacteria were significantly altered by AMC at day 5 and returned to baseline at day 8. Numerous publications report modifications of fecal microbiota after AMC treatment but only at genus or phylogenetic group level. An increase of enterobacteria was notably described as well as an increase of Bacteroides and a decrease of Clostridium coccoides phylogenetic groups compared to the control microbiota [32,33]. At the species level, using clone library comparison, Bacteroides distasonis replaced members of B. fragilis group in microbiota of a 39 year-old subject, no sequences corresponding to Clostridium coccoides group or to Bifidobacterium spp. were detected at day 4 of AMC treatment, whereas these two groups represented a third of the sequences detected on day 0. Conversely, 34 of sequences detected on day 4 were members of Enterobacteriaceae which represented only 2 of the day 0 sequences [34]. In this case, bifidobacteria were not recovered at day 24, two weeks after the end of the AMC treatment. In the present study, bacterial TTGE were performed to monitor b.Y 33, TTGE bands corresponding to Rf of B. adolescentis were detected in 83 of subjects, Rf of B. longum in 55 of subjects, Rf of B. pseudocatenulatum/B. catenulatum group in 55 of subjects, Rf of B. bifidum in 22 of subjects, Rf of B. dentium in 11 of subjects and those of B. breve in 17 of subjects. At day 64 (2.260.2 species per sample), only few differences were still observed in species identification. Since Bifidobacterium bands were all identified, the Jaccard’s similarity coefficient equivalent to Dice’s was calculated withFigure 4. TTGE profiles representing the bifidobacterial diversity of fecal samples from two healthy volunteers (A and B) before and after AMC exposure. 1:day-12; 2:day-6; 3:day 0; 4:day 5; 5:day 8; 6:day 12; 7:day 19; 8:day 26; 9:day 33; 10:day 64. a, b, d, e, f, a9: B. adolescentis; c, g: B. bifidum; b9: B. pseudocatenulatum; c9: B. longum; d9: B. dentium; e9: B. breve; f9: B. pseudolongum; g9: B. animalis subsp. lactis. doi:10.1371/journal.pone.0050257.gBifidobacterium Monitoring after AMC ExposureFigure 5. Mean similarity coefficients of specific Bifidobacterium TTGE profiles of samples collected before and after AMC exposure (day0 ay5) and calculated according to the reference period (day-12 day-6 day 0; n = 17). doi:10.1371/journal.pone.0050257.gspecies as characters and showed that changes concerned species and not only strains within a species (Fig. 7).DiscussionA previous study on the same 18 volunteers focusing only on bacterial resistance showed that the administration of AMC increased the amoxicillin resistant Escherichia coli and enterococci.From a baseline of less than 1 , more than 30 of resistant E. coli and 6 of resistant enterococci were observed and progressively decreased to baseline at day 12 [31]. In the present study, the impact of a 5-day AMC treatment was quantitatively and qualitatively assessed at short- and long-term on total microbiota and on fecal Bifidobacterium species in 18 healthy men. Bifidobacteria were detected in all fecal microbiota from the 18 subjects (100 ) before exposure to AMC. The counts of totalFigure 6. Occurence rate of Bifidobacterium species monitored before and after AMC exposure (day0 ay5); n = 18 adults. doi:10.1371/journal.pone.0050257.gBifidobacterium Monitoring after AMC ExposureFigure 7. Change of species after the AMC exposure. doi:10.1371/journal.pone.0050257.gbacteria and total bifidobacteria were significantly altered by AMC at day 5 and returned to baseline at day 8. Numerous publications report modifications of fecal microbiota after AMC treatment but only at genus or phylogenetic group level. An increase of enterobacteria was notably described as well as an increase of Bacteroides and a decrease of Clostridium coccoides phylogenetic groups compared to the control microbiota [32,33]. At the species level, using clone library comparison, Bacteroides distasonis replaced members of B. fragilis group in microbiota of a 39 year-old subject, no sequences corresponding to Clostridium coccoides group or to Bifidobacterium spp. were detected at day 4 of AMC treatment, whereas these two groups represented a third of the sequences detected on day 0. Conversely, 34 of sequences detected on day 4 were members of Enterobacteriaceae which represented only 2 of the day 0 sequences [34]. In this case, bifidobacteria were not recovered at day 24, two weeks after the end of the AMC treatment. In the present study, bacterial TTGE were performed to monitor b.
