IMPORTANT PATHOGENIC BACTERIA 109 



EXERCISE 2. THE PYOGENIC GROUP (SUBGROUP B) 



Members 



Streptococcus pneumoniae. 

 Micrococcus zymogenes. 

 Micrococcus gonorrheae. 



M. gonorrheae is difficult to cultivate on labora- 

 tory media. It is a parasite and requires special media 

 for cultivation. For these reasons it is sufficient to 

 study the characteristic morphology in smears made 

 from gonorrheal pus. Methylene blue or Pappenheim's 

 stain (p. 45) and Gram stains should be made. 



Inoculate agar slants from laboratory cultures of 

 Str. pneumoniae and M. zymogenes. 

 References (M. zymogenes} 



MacCallum and Hastings, Jour. Exper. Med., 1899, 4, p. 521. 



Harris and Longcope, Centralbl. f. Bakt., 1901, 30, Abt. 

 !> P- 353 (printed in English). 



Birge, Johns Hopkins Hospital Bull., 1905, 16, p. 309. 



1. Routine study. Note the microscopic appear- 

 ance of both organisms and the action of M. zymogenes 

 on milk and gelatin. 



2. Special study. The staining of capsules from 

 a milk culture of Str. pneumoniae. Three methods 

 may be applied for this stain: 



First method (Friedlander's method) 



1. Prepare a stain by the following formula: 



Glacial acetic acid i part 



Saturated alcoholic solution of gentian 



violet 5 parts 



Distilled water 10 parts 



2. Prepare a film in the usual manner from a 24- 

 hour-old culture in milk. 



