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Updated: Jun 19, 2026

Operating and Biocontainment Procedures of a Facility for Laboratory Mice with a Natural Microbiome: Immunophenotyping Procedure
Published on: December 13, 2024
Intestinal microflora functions in laboratory mice claimed to harbor a "normal" intestinal microflora. Is the SPF
Elisabeth Norin1, Tore Midtvedt
1Department of Microbiology, Tumor and Cell biology, Nobels väg 16, Karolinska Institutet, 17177 Stockholm, Sweden. elisabeth.norin@ki.se
Abstract:
For many years, laboratory animal breeders have used a mixture of eight bacterial strains, the so-called Altered Schaedler Flora (ASF) to inoculate Caesarian derived offspring when establishing colonies of Specific Pathogen Free (SPF) rodents fulfilling the criteria worked out by regulatory agencies as AALAS, FELASA, etc. However, recently it was shown in this journal that such SPF animals harbored a fecal flora far different from that of feral mice. Over the years, we have worked with functional aspects of host-microbe interactions(s) and the aim of the present study was to analyze some intestinal microbial biochemical activities in mice harboring an ASF flora. In the five parameter studied, the ASF mice showed a pattern similar to what is found in germfree mice and rats, demonstrating an absence of microorganisms capable of performing these reactions. These findings call for a re-considering of the SPF concept. Presence of important microbiological functions should be taken into consideration when rodents are used in biomedical research.
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