Endotoxic activity in faeces of mice from different microbiological environments.

Abstract Chromogenic Limulus amoebocyte lysate (LAL) tests were evaluated for measuring endotoxic activity in faeces of mice from different microbiological environments. Faeces of BALB/c mice from germ-free (GF), specific-pathogen-free (SPF) and conventional (CV) colonies had no inhibitory activity on the test reaction. GF and SPF faeces had heat-labile non-specific amidase activity which gave false-positive reaction, while CV did not. GF faeces had a heat-stable non-endotoxic effect on the LAL system. Average endotoxin levels in faeces of GF, SPF and CV mice were 0.2, 0.8 and 17 to 24 μg/g wet weight, respectively. Results suggest that the microbiological status of mice influences not only the faecel endotoxin level but also the specificity of the test reaction.