PYOGENIC BACTERIA. 277 



dis albus has but slight virulence. Out of forty-five cases in which 

 a bacteriological examination was made this micrococcus was ob- 

 tained in pure cultures in thirty -three ; in five cases it was associated 

 with Staphylococcus pyogenes aureus, in one case with Streptococ- 

 cus pyogenes, in three cases Streptococcus pyogenes was obtained 

 alone. 



In abscesses resulting from inflammation of the middle ear the 

 micrococcus commonly known under the name of " diplococcus 

 pneumonias " Micrococcus pneumoniae crouposae has been obtained 

 in pure cultures in a considerable number of cases when the pus has 

 been examined immediately after paracentesis of the tympanic mem- 

 brane. We shall not, however, describe this among the pyogenic 

 bacteria, but will give an account of it in the following section (Bac- 

 teria in Croupous Pneumonia, etc.). Bacillus pyocyaneus, which is 

 described by some authors among the pyogenic bacteria, is found 

 only in the pus of open wounds, where its presence is evidently acci- 

 dental. We shall describe it among the chromogenic saprophytes. 



1. STAPHYLOCOCCUS PYOGENES AUREUS. 



Synonym. Micrococcus of infectious osteomyelitis (Becker). 



Observed by Ogston (1881) in the pus of acute abscesses, but not 

 differentiated from the associated staphylococci and the streptococ- 

 cus of pus. Obtained by Becker from the pus of osteomyelitis (1883). 

 Isolated from the pus of acute abscesses and accurately described by 

 Rosenbach (1884) and by Passet (1885). 



The Staphylococcus pyogenes aureus is a facultative parasite, and / 

 is the most common pyogenic micrococcus found in suppurative pro- 

 cesses generally. But it is also a common and widely distributed 

 saprophyte, which finds the conditions necessary for its existence on 

 the external surface of the human body and of moist mucous mem- 

 branes. This is shown by the researches of numerous bacteriolo- 

 gists. Thus Ullmann found it upon the skin and in the secretions of 

 the mouth of healthy persons, and also in the dust of occupied apart- 

 ments, in water, etc.; Bockhart obtained it in cultures from the 

 surface of the body and from the dirt beneath the finger nails of 

 healthy persons ; Biondi, Vignal, and others in the salivary secre- 

 tions ; B. Frankel in mucus from the pharynx ; Von Besser and 

 Wright in nasal mucus ; Escherich in the alvine discharges of 

 healthy infants ; C. Frankel in the air ; and Liibbert in the soil. Its 

 presence in the air, in water, or in the soil is, however, quite excep- 

 tional, and is probably to be considered the result of accident, its 

 normal habitat as a saprophyte appearing to be rather upon the sur- 

 face of the b 9 dy and of mucous membranes. 



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