Lepromin vs purified bacillus suspension. I. Preparation of a purified bacillus suspension (with a note on nile-blue staining of smears)

ABSTRACT

The various methods that have been employed for obtaining tissue-free suspensions of leprosy bacilli are reviewed briefly. Most of them were eliminated from consideration for practical purposes, because they deo not meet the primary requirements of simplicity of technique or - and especially - of economy of the leproma material. After experimentation it was found most practical to harvest the bacilli from the pulped leproma tissue with chloroform, as in the first step of preparing Dharmendra's antigen, and then to dilute the pooled chloroform extract with two times its volume of acetone, after which the bacillary bodies are deposited by centrifuging and resuspended in phenol-saline. The bacilli so obtained are affected to some degree by the chloroform, being distinctly paler in color and of thinner appearance after Ziehl-Neelsen staining than those in the standard lepromin made from an aliquot of the same starting material. Consequently, the final suspension was made up with approximately 50 per cent morer bacilli than the lepromin made for use as the control in clinical tests.