An outbreak of disease in multiparous females occurred in one isolator in a
colony of Balb/-c germ-free mice. The affected isolator had been accidenta
lly contaminated with Clostridium perfringens. Gross and histological exami
nation of the diseased mice revealed lesions in the lungs, heart and intest
inal tract. Lesions in the valvular endocardium and vascular walls were clo
sely associated with bacterial colonies and septic thrombi containing Gram-
positive rods. C perfringens type B was recovered in pure culture from the
faeces, intestinal contents and atrial thrombi of the sick mice. Intestinal
lesions varied, depending on the region of the intestine. The ileum showed
shortened villi and ulceration of the mucosa. The duodenum of all the affe
cted mice showed microscopic foci of polypoid adenomatous growth of the cry
pt epithelium. The significance of these unusual neoplastic lesions is disc
ussed in the context of the growing evidence of an association between cell
growth and bacterial cell products. (C) 1999 Harcourt Publishers Ltd.