Abstract
A contamination withMycobacterium scrofulaceumwas experienced in a colony of BALB/c-nu/numice. The contamination was noticed after introduction of C57BL/6 and C57BL/6. Lyt 1. 1 strains into facilities that kept the colony.M. scrofulaceumseemed to be spread by oral infestation and cross-contamination of fecal excretions dung handling of the mice. The organisms were shed continually or intermittently into feces of weanednu/+andnu/numice of BALB/c background, and were isolated from the mesenteric lymph nodes and spleen of some of the mice. Some of the bacillus-carrying mice developed serum antibody toM. scrofulaceumof IgG and IgA classes and gave a low degree of hypersensitivity to PPD fromM. tuberculosis.
