BACILLUS SMEGMATIS 619 



They are not easily stained, and though less resistant in this respect 

 than the tubercle bacillus, they yet belong distinctly to the group of 

 acid-fast bacilli. Once stained by the stronger dyes, such as carbol- 

 fuchsin or anilin-water-gentian -violet, they are tenacious of the dye, 

 though less so than tubercle bacilli. 



The identification of the smegma bacillus by staining methods 

 has become of practical importance since Fraenkel, 5 Miiller, 6 and 

 others have demonstrated the occasional presence of acid-fast bacilli, 

 probably of the smegma group, in sputum, and in secretions from the 

 tonsillar crypts and throat. The methods of differentiation which have 

 been found most practical are those which depend upon differences in 

 the retention of stain shown by these bacilli. While it may be stated 

 as a general rule that the smegma bacilli are more easily decolorized 

 than tubercle bacilli, it is nevertheless important that a control, as sug- 

 gested by Wood, be made with known tubercle bacilli whenever a slide 

 of suspected smegma bacilli is examined. For the actual differentiation 

 an excellent method is that of Pappenheim, described in detail in the 

 section on Staining, page 125. This method depends upon the fact 

 that prolonged treatment with alcohol and rosolic acid decolorizes the 

 smegma bacilli but not the tubercle bacilli. Coles 7 has stated that 

 smegma bacilli will resist Pappenheim's decolorizing agent for four hours 

 at the most, while tubercle bacilli will retain the stain, in spite of such 

 treatment, for as long as twenty-four hours. 



The smegma bacilli have no pathogenic significance. They are 

 found upon human beings as harmless saprophytes, and all attempts to 

 infect animals have so far been unsuccessful. They are cultivated 

 with great difficulty, first cultivations from man being successful only 

 upon the richer media containing human serum or hydrocele fluid. 

 After prolonged cultivation upon artificial media they may be kept 

 alive upon glucose agar or ascitic agar. Their growth is slow; and the 

 colonies, appearing within five or six days after inoculation, are yellowish 

 white, corrugated, and not unlike tubercle-bacillus colonies. 



5 Fraenlcel, Bcrl. klin. Woeh., 1898. 

 41 Miiller, Deut. med. VVoch., 1898. 

 7 Coles, Jour, of State Med., 1904. 



