CHAPTER XXIV. 



THE PRODUCERS OF ABSCESSES, CELLULITIS, SEPTICAEMIA. ETC. 

 THE STAPHYLOCOCCI. 



STAPHYLOCOCCI were first obtained from pus by Pasteur in 1880. 

 In 1881 Ogston showed that they frequently occurred in abscesses, and 

 in 1884 Rosenbach fully demonstrated their etiological importance in 

 circumscribed abscesses, osteomyelitis, etc. Of all the staphylococcus 

 varieties the staphylococcus pyogenes aureus is by far the most important 

 and will, therefore, be first described. 



The Staphylococcus Pyogenes Aureus. 



The staphylococcus pyogenes aureus is one of the commonest patho- 

 genic bacteria, being usually present in the skin or mucous membranes, 

 and is the organism most frequently concerned in the production of 

 acute, circumscribed, suppurative inflammations. 



Morphology. Small, spherical cells, having a diameter of 0.7/* to 0.9//, 

 occurring solitary, in pairs as diplococci, in short rows of three or 

 four elements, or in groups of four, but most commonly in irregular 

 masses, simulating clusters of grapes; hence the name staphylococcus. 

 (See Fig. 101.) 



Staining. It stains quickly in aqueous solutions of the basic aniline 

 colors and with many other dyes. When previously stained with 

 gentian violet it is not decolorized by Gram's method. When slightly 

 stained each sphere frequently is seen to be already dividing into two 

 semispherical bodies. 



Biology. The staphylococcus pyogenes aureus is an aerobic, /ac?//- 

 tative anaerobic micrococcus, growing at a temperature from 8 to 

 43 C., but best at 25 to 35 C. The staphylococci grow readily on all 

 the common laboratory media, such as milk, bouillon, nutrient gelatin, 

 or agar. A slightly alkaline reaction to litmus is best for the growth 

 of the staphylococci, but they also grow in slightly acid media. 



Cultivation. GROWTH ix NUTRIENT BOUILLON. The growth of the 

 staphylococcus is rapid, reaching about 50,000,000 per c.c. at the end 

 of twenty-four hours at 30 C. The bouillon is cloudy and frequently 

 has a thin pellicle. Later a shiny sediment forms. The odor is dis- 

 agreeable. In peptone-water growth occurs with indol production. 



GROWTH ON GELATIN. Grown on gelatin plates it develops, at room- 

 temperature, within forty-eight hours, punctiform colonies, which, when 

 examined under a low-power lens, appear as circular disks of a pale- 



