Contamination of Healthy Mice with Murine Leprosy-like Acid-Fast Bacillus

Abstract

The subcutaneous connective tissue, lymphnodes and organs of healthy mice were examined in detail by the spread tissue preparation and stamp smear methods and staining with the Ziehl-Neelsen stain. Material from bacillus positive animals was cultivated onto artificial media or inoculated into other mice and numerous acidfast bacilli were isolated. Leproma was produced in mice inoculated with the isolated organisms and identification tests showed many of the organism to have properties similar to the murine leprosy bacillus.
The organism has been called the murine leprosy-like acid-fast bacillus since there are several points of difference such as the absence of active infection in the original animal, the lack of leproma production but proliferation in the lungs in the next generation of mice and the simple conglomeration of the organism rather than the presence in the cells. The source of infection is discussed.
As a result of the findings in this study, it is suggested that caution must be exercised in experiments in which mice are inoculated with the leprosy bacillus, and that acid-fast bacillus present in natural circumstances must be noted as an infectious agent of natural murine leprosy.
This study was supported in part by a grant from WHO.