210 MICROBIOLOGY 



action is shown by decolorization in cultures of litmus, methy- 

 lene-blue and rosanalin. 2 



Resistance. Although it does not form spores Micrococ- 

 cus pyogenes is more resistant to heat than many other purely 

 vegetative forms. The thermal death point given for Micro- 

 coccus pyogenes by Sternberg 3 lies between 56 and 58 C., 

 the time of exposure bging ten minutes. The same, author 

 states that when in a completely dried state, it is still more re- 

 sistant, a temperature of from 90 to 100 C. being required 

 for its destruction. Against low temperatures, Micrococcus 

 pyogenes is extremely resistant, repeated freezing often failing 

 to sterilize cultures. Park states that 30 per cent of the or- 

 ganisms remained alive after being frozen for 30 minutes in 

 liquid air. They are destroyed by corrosive sublimate in solu- 

 tion of 1-1000 and in a 3 per cent carbolic acid solution in 

 irom 10 to 15 minutes. 



Pathogenesis. This organism is found in a large number 

 of abscesses, suppurating lesions, and occasionally in general 

 sepsis, in a number of species of animals. It is one of the most 

 important of the wound-infecting organisms. It is not the 

 cause of any of the recognized specific infectious diseases. The 

 susceptibility of animals to it varies greatly, depending upon 

 resistance of the individual and virulence of the organism. 

 Generally speaking, animals are less susceptible than man. 

 Of the laboratory animals, the rabbit is most susceptible. 

 Guinea pigs are more resistant. The subcutaneous inocula- 

 tion usually results in the production of a local abscess. In 

 case the animal is somewhat resistant, the inflammatory 

 process may extend somewhat. When inoculated intraven- 

 ously, sepsis and occasionally a pyemic condition follows. 

 Occasionally, deep seated abscesses containing this organism 

 are found. We have two specimens of suppuration beneath 

 the endocardium in cattle associated with this organism. 



Hemolysis. Kraus 4 has reported a hemolytic action of 



2 Mueller. Centralbl. f. Bakt., Bd. XXVI (1899) p. 801. 



3 Sternberg. Loc. cit. 



4 Kraus. Wien klin. Wochenschrift, Vol. Ill, 1900. 



