Establishment of specific pathogen-free (SPF) rat colonies using gnotobiotic techniques

Gnotobiotic Wistar rats were produced using gnotobiotic techniques, which w ere established in the production of a SPF mouse colony, in order to establ ish a barrier-sustained colony. One strain of Escherichia coli, 28 strains of Bacteroidaceae (B-strains), three strains of Lactobacillus (L-strains) a nd a chloroform-treated fecal suspension (CHF, Clostridium mixture) were pr epared from conventional Wistar rats as the microflora source. Two groups o f limited-flora rats, E, coli plus B-strains and E. coli plus CHF, were pro duced. After confirmation that Clostridium difficile was not detected in th e CHF-inoculated rats, two groups of limited-flora rats were transferred to an isolator and housed together in a cage. These rats were then orally ino culated with L-strains. The gnotobiotic rats showed colonization resistance to Pseudomonas aeruginosa, and the number of E. coli in the feces was 10(5 ) to 10(6)/g. The gnotobiotic rats were transferred to a barrier room as a source of intestinal flora for SPF colonies, In the SPF rats, basic cecal f lora was mainly composed of Bacteroidaceae, clostridia, fusiform-shaped bac teria and lactobacilli, and did not change over a long period. Their flora became similar to that of conventional rats.