288 THE PYOGENIC COCCI 
THE STAPHYLOCOCCUS GROUP. 
MicrococcusAureus.— Synonyms.— Staphylococcus pyogenes aureus; 
Staphylococcus aureus; Micrococcus pyogenes aureus; Micrococcus 
saUvarius aureus. 
Historical.— Staphylococci probably were first seen by Rindfleischi 
in tissues from infected wounds. Somewhat later Klebs saw them 
in the unstained pus from infected gun-shot wounds. This observa- 
tion was denied, then confirmed by Billroth .^ Pasteur^ repeatedly 
isolated organisms from the pus of furuncles, and in one case of osteo- 
myelitis. These bacteria, from their arrangement and association, 
must have been staphylococci; he suggested their etiological relation- 
ship to these lesions. To Rosenbach,'* however, belongs the priority 
of growing staphylococci in cultures of undoubted purity. 
Morphology.— The organisms in the free state are spherical, measur- 
ing from 0.7 to 0.9 micron in diameter. Those just about to divide 
are frequently oval. They occur singly, in pairs, or in irregular masses, 
both in culture and in pus; rarely chains of four to six cocci are found. 
Staphylococci are non-motile and possess no flagella; they do not 
form capsules, and spores have not been observed. They stain readily 
with ordinary anilin dyes, some individuals more intensely than their 
fellows. They are Gram-positive. 
Isolation and Culture.— Staphylococci are readily obtained in pure 
culture by plating or streaking the suspected material directly upon 
agar or gelatin. Blood-agar is an excellent medium. The colonies on 
gelatin after thirty to forty-eight hours' incubation at room temperature 
become visible as gray, glistening growths 0.5 to 1 mm. in diameter; 
somewhat later the colonies sink into saucer-shaped depressions of 
liquefied gelatin. The bacteria collect at the bottom of the depression 
and soon become golden-yellow in color. The growth upon agar 
plates at 37° C. is more rapid; at the end of forty-eight hours' incuba- 
tion the colonies are golden-yellow and have attained a diameter of 
1 to 3 mm. 
Staphylococci grow readily in the ordinary cultural media. Gela- 
tin, coagulated blood serum (sugar-free) and casein are liquefied. 
Acid is produced in glucose, lactose, saccharose and mannitol broths. 
Milk is coagulated, usually within three days at 37° C.; many strains 
subsequently partially digest the coagulum. In plain and glucose 
broths a turbidity is produced after twelve to fourteen hours' incuba- 
tion at 37° C.; after forty-eight hours' growth a golden-yellow sedi- 
ment collects in the bottom of the tubes. Growth on slanted agar is 
golden-yellow in color, moist and spreading. Pigment production is 
especially luxuriant on slanted potato. 
1 Lehrbuch d. pathologischen Gewebelehre, 1886, I aufl., 204. For literature. 
- Beitr. z. path. Anat. der Schusswunden, Leipzig, 1872. 
3 Compt. rend. Acad. Sci., 1880, 90, 1035. 
* Mikroorganismen bei den Wundinfektionskrankheiten des Menschen, Wiesbaden, 
1884, p. 19. 
