Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/16/2009
Publication Date: 6/6/2009
Citation: Overstreet, A., Jergens, A., Ramer-Tait, A., Gallup, J., Ziemer, C.J., Atherly, T.A., Wannemuehler, M. 2009. Modification of composition and spatial distribution of intestinal microbiota following antibiotic therapy in immunocompetent defined flora C3H/HeN mice [abstract]. In: Proceedings of Digestive Disease Week, May 31-June 4, 2009, Chicago, IL CDROM. Interpretive Summary:
Technical Abstract: Background: Luminal bacteria and/or their products play a pivotal role in the pathogenesis of chronic intestinal inflammation associated with inflammatory bowel diseases (IBD). While host responses to resident flora may initiate IBD, the subsets of bacteria responsible for mediating inflammation in most models are difficult to ascertain due to the complex native microbiota. Microbial assessment following broad-spectrum antibiotic therapy has demonstrated qualitative changes in bacterial composition, but alterations in the density and spatial distributions of these bacteria are poorly understood. Aim: To investigate colonization dynamics of a defined flora in C3H/HeN mice receiving antibiotics using quantitative PCR (qPCR) and fluorescence in situ hybridization (FISH) techniques. Methods: Defined flora C3H/HeN mice harboring the eight member altered Schaedler flora (ASF) were selectively treated with streptomycin, neomycin, metronidazole, or ampicillin in drinking water. Quantitative PCR was performed on fecal DNA to quantify the numbers of bacteria present using primers specific to each ASF member. The spatial distribution of ASF bacteria in colonic tissues was determined using FISH for bacteria (EUB338) and for the major representatives of the ASF (Bacteroides - BAC303, Eubacterium rectale–Clostridium coccoides group - EREC482, Lactobacilli - LAB158) and ASF457 (Mucispirillum schaederleri). Results: Control DF mice showed no changes in ASF bacterial numbers in response to sham therapy; however, antibiotic-treated DF mice showed selective changes in ASF bacterial densities. In general, antibiotic treatment decreased all ASF bacteria based on qPCR analysis (ampicillin reduced all to below detection limits). A few ASF increased with antibiotic treatment as follows: ASF 502 (Clostridium sp) and ASF519 (Bacteroides distasonis) with streptomycin; ASF519 with neomycin; ASF361 (Lactobacillus murinus) with metronidazole. FISH analysis corroborated the qPCR findings and demonstrated antimicrobial treatment altered spatial distributions of ASF bacteria. In particular, streptomycin treatment caused increased mucosal association of all ASF members versus control DF mice. ASF519 was more mucosally-associated in DF mice treated with neomycin; while metronidazole dramatically increased intraluminal Lactobacilli. Conclusions: We have characterized the colonization dynamics of ASF bacteria in antibiotic treated C3H mice and demonstrated changes in density and spatial distributions of the resident microbiota. This model of bacterial dysbiosis will be useful in elucidating the roles of commensal microbiota in affecting the susceptibility of mice to colitic insults.