title: Alteration of the ileal microbiota of weanling piglets by the growth-promoting antibiotic chlortetracycline.
abstract: Antibiotics such as chlortetracycline (CTC) have been used to promote growth of pigs for decades, but concerns over increased antibiotic-resistant infections in humans have prompted the development of alternative strategies. Developing alternatives to antibiotic growth promoters (AGPs) could be informed by information on the mechanisms of growth promotion, notably, how AGPs affect the microbial populations of the gastrointestinal tract. Pigs from three sows were aseptically delivered by cesarean section. Six piglets were distributed to each of two foster mothers until weaning, when piglets were fed a diet with or without 50 mg/kg CTC for 2 weeks. The ileal bacterial microbiota was characterized by using a cultivation-independent approach based on DNA extraction, PCR amplification, cloning, and sequencing of the 16S rRNA gene pool. The ileal and mucosal communities of these growing pigs were dominated by Lactobacillus bacteria, various members of the family Clostridiaceae, and members of the poorly known genus Turicibacter. Overall, CTC treatment resulted in three shifts: a decrease in Lactobacillus johnsonii, an increase in L. amylovorus, and a decrease in Turicibacter phylotypes. The composition of the microbiota varied considerably between individual pigs, as revealed by shared operational taxonomic units (OTUs) and similarity (SONS) analysis (theta(YC) values). While the observed variation between untreated pigs obscured the possible effect of CTC, integral-LIBSHUFF and SONS analyses of pooled libraries indicated a significant shift due to CTC in both the lumen and the mucosa, with some OTUs unique to either treated or control ileum. DOTUR analysis revealed little overlap between control and treated communities at the 3% difference level, indicating unique ileal communities in the presence of CTC.
authors.affiliation: Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota 57007, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Rettedal
authors.forename: Sébastien
authors.initials: S
authors.lastname: Vilain
authors.forename: Stacy
authors.initials: S
authors.lastname: Lindblom
authors.forename: Kelly
authors.initials: K
authors.lastname: Lehnert
authors.forename: Clay
authors.initials: C
authors.lastname: Scofield
authors.forename: Sajan
authors.initials: S
authors.lastname: George
authors.forename: Sharon
authors.initials: S
authors.lastname: Clay
authors.forename: Radhey S
authors.initials: RS
authors.lastname: Kaushik
authors.forename: Artur J M
authors.initials: AJ
authors.lastname: Rosa
authors.forename: David
authors.initials: D
authors.lastname: Francis
authors.forename: Volker S
authors.initials: VS
authors.lastname: Brözel
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D044822:Biodiversity; D002751:Chlortetracycline / Q000008:administration & dosage / Q000494:pharmacology*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D007082:Ileum / Q000382:microbiology*; D036341:Intercellular Signaling Peptides and Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000382:microbiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013552:Swine
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D036341:Intercellular Signaling Peptides and Proteins; D012336:RNA, Ribosomal, 16S; D002751:Chlortetracycline