114 Microbes and You 



seen in diseased tissue of lepers leads us to believe that they are the 

 etiology of the disease. 



Saprophytic acid-fast bacteria are troublesome and can lead 

 to false conclusions unless the clinician understands the problem. 

 An organism known as Mijcohacterium smegmatis is a normal 

 saprophytic inhabitant of the prepuce of males and the external 

 labia of women. If urine specimens are collected without taking 

 proper precautions, such as the use of a catheter which permits 

 the collection of urine directly from the bladder or from the 

 kidneys, acid-fast bacteria found in urine specimens might lead 

 to a false diagnosis of tuberculosis of the genito-urinary tract. 



GRANULE STAINS 



Specialized stains have been developed to detect more easily 

 granules in bacteria. Loeffler's alkaline methylene blue encourages 

 the irregular staining so characteristic of t)'pical diphtheria organ- 

 isms. Ponder's stain and Gohar's technic have also come into 

 popular use for similar studies. The ingredients of all these stains 

 and the technics for their use may be found in bacteriology 

 laboratory manuals. 



SPORE STAINS 



Bacterial spores are usually refractile to the common technics 

 employed for staining bacteria, but once the spores have stained, 

 they retain the dye longer than the vegetative protoplasm. Mala- 

 chite green is a very satisfactory dye to be forced into spores with 

 the aid of heat. A counterstain of safranin will yield a pink vegeta- 

 tive cell in which the green-stained spore can be observed. Carbol 

 fuchsin is another satisfactory dye for primary staining with 

 methylene blue as a counterstain. Many combinations have been 

 suggested for spore-staining, and a number of these methods are 

 quite satisfactory. The low permeabilit)^ of the spore walls to 

 dyestuffs is the most common explanation of spore resistance to 

 staining and to subsequent decolorization. Without the use of 

 heat, a staining time of from 2 to 4 hours is not uncommon. In 

 ordinary staining without the application of heat the spore stands 

 out as a clear refractile bodv within the cell. At times it is 



