PYOGENIC BACTERIA. 373 
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 
pneumoniz ”—Micrococcus pneumoniz crouposee—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. 
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 body and of mucous membranes. 
