title: Amoxicillin treatment modifies the composition of Bifidobacterium species in infant intestinal microbiota.
abstract: OBJECTIVE
  Amoxicillin is a beta-lactam antibiotic largely used in childhood. However only few studies described its impact on composition of children gut microbiota, in particular on Bifidobacterium populations considered as beneficial microorganisms. In this study, the impact on faecal Bifidobacterium species of a seven-day amoxicillin treatment was quantitatively and qualitatively assessed in infants during an episode of acute respiratory infection.
  
  
  METHODS
  Faecal samples from 31 infants were obtained on day 0 (just before amoxicillin therapy) and on day 7 (the end of therapy). Total DNA was extracted and bifidobacteria were quantified using real-time PCR. Predominant Bifidobacterium species were then identified using specific PCR-TTGE.
  
  
  RESULTS
  Bifidobacteria concentrations were not significantly altered by amoxicillin compared to the healthy group. However, amoxicillin treatment induced a complete disappearance of Bifidobacterium adolescentis species (occurrence rate of 0% versus 36.4% in healthy group, P < 0.001), a significant decrease in the occurrence rate of Bifidobacterium bifidum (23% versus 54.5% in healthy group, P < 0.05), but did not affect Bifidobacterium longum (93.5% versus 100% in healthy group) and Bifidobacterium pseudocatenulatum/B. catenulatum (about 55% in both groups). The number of Bifidobacterium species per microbiota significantly decreased from 2.5 +/- 1 for healthy group to 1.8 +/- 0.9 for treated infants (P < 0.05).
  
  
  CONCLUSIONS
  This study showed that a 7 day amoxicillin treatment did not alter the counts of Bifidobacterium. However amoxicillin can have an impact by changing the microbiota at the species level and decreased the diversity of this population.
authors.affiliation: Laboratoire de Biologie EA3199, Conservatoire national des arts et métiers, 2 rue Conté, Paris, France.
authors.forename: I
authors.initials: I
authors.lastname: Mangin
authors.forename: A
authors.initials: A
authors.lastname: Suau
authors.forename: M
authors.initials: M
authors.lastname: Gotteland
authors.forename: O
authors.initials: O
authors.lastname: Brunser
authors.forename: P
authors.initials: P
authors.lastname: Pochart
mesh_terms: D000658:Amoxicillin / Q000008:administration & dosage*; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D058491:Bacterial Load; D001644:Bifidobacterium / Q000187:drug effects / Q000302:isolation & purification*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005243:Feces / Q000382:microbiology; D005260:Female; D006801:Humans; D007223:Infant; D007422:Intestines / Q000382:microbiology*; D008297:Male; D054892:Metagenome / Q000187:drug effects*; D016133:Polymerase Chain Reaction
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D000658:Amoxicillin