Some Artifacts Encountered in Stained Preparations of Tubercle Bacilli

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Abstract
On the basis of elaborate technics not usually employed for preparing Mycobacterium tuberculosis for staining, the writers claim that non-acid-fast rods and granules are artifacts. In procedure (A) a 25% soln. of formalin was employed for fixation for 1 hr., followed by 30 min. washing in dist. water. The organisms were then transferred to a slide coated with a thin film of albumen. In procedure (B) the organisms were permitted to dry slightly and were then spread with a platinum loop, the mixture assuming a pasty consistency. Stained slides treated by (A) showed only acid-fast forms; those treated by (B) showed many non-acid-fast forms, the % roughly proportional, according to the writers, to the effort expended with the loop. In procedure (C) 7-day-old membrane growths were fixed in 15% formalin or 95% alcohol, carried through alcohol and xylol, and imbedded in paraffin. The sections were mounted on slides covered with a film of albumen. Controls were passed back through alcohols and into water prior to staining. Controls showed only acid-fast cells, the other preparations showed many non-acid-fast forms which the writers claim were caused by traumatization with the microtome blade.