Alteration of the Ileal Microbiota of Weanling Piglets by the Growth-Promoting Antibiotic Chlortetracycline

• DOI: 10.1128/aem.02220-08
• Publication Date: 2009-07-18T01:33:01Z
• Authors: Elizabeth Rettedal; Sébastien Vilain; Stacy Lindblom; Kelly Lehnert; Clay Scofield; Sajan George; Sharon Clay; Radhey S. Kaushik; Artur J. M. Rosa; David Francis; Volker S. Brözel
• Keywords: DNA, Bacterial; 0301 basic medicine; 2. Zero hunger; Bacteria; Swine; Molecular Sequence Data; Biodiversity; Sequence Analysis, DNA; DNA, Ribosomal; 630; Anti-Bacterial Agents; 3. Good health; 03 medical and health sciences; Ileum; RNA, Ribosomal, 16S; Animals; Cluster Analysis; Intercellular Signaling Peptides and Proteins; Intestinal Mucosa; Phylogeny; Chlortetracycline

ABSTRACTAntibiotics 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 byLactobacillusbacteria, various members of the familyClostridiaceae, and members of the poorly known genusTuricibacter. Overall, CTC treatment resulted in three shifts: a decrease inLactobacillusjohnsonii, an increase inL.amylovorus, and a decrease inTuricibacterphylotypes. The composition of the microbiota varied considerably between individual pigs, as revealed by shared operational taxonomic units (OTUs) and similarity (SONS) analysis (θYCvalues). While the observed variation between untreated pigs obscured the possible effect of CTC, ∫-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.