Stain techniques and the morphology of Mycobacterium leprae.

A comparative study of acid-fast stain techniques has shown that some methods in common use give divergent values for the MI , and smaller but significant discrepancies in the BI . The methods used by Rees and Valent ine and by Shepard to equate solid staining with viability are in fairly good agreement. The heating of carbol-fuchsin stain is the factor which causes the most variation in the MI , but fixation, time of staining, and method of differentiation all have some bearing on the results. I t is thought that all the effective staining procedures produce some alteration of bacterial morphology. The need for standardization and the suitability of certain methods for routine application are discussed.