MICROBIAL DISEASES OF MAN AND ANIMALS. 591 



STAPHYLOCOCCIC INFECTIONS.* 



Boils, Abscesses, Wounds, Osteomyelitis, Pyemia, Etc. 

 Micrococcus pyogenes var. aurens, etc. 



Infections of this order are found throughout the world and because 

 of the association of staphylococci and streptococci with the large majority 

 of purulent inflammations, these organisms are called the pyogenic cocci. 



No specific disease is produced, but chiefly boils, circumscribed 

 abscesses, infected wounds, osteomyelitis, pyaemia, etc. The symptoms 

 alone will not indicate whether staphylococci or streptococci are present, 

 but a low grade of infection with more pus and less constitutional 

 disturbance tends to indicate the former, and staphylococci tend to 

 pyaemia rather than to septicaemia. 



Pasteur, Koch, Ogston and Rosenbach established the importance 

 of these organisms. 



Staphylococci stain readily in pus with aniline dyes, and simple 

 sowing upon ordinary media is usually sufficient to obtain growth, 

 plating should be resorted to. 



While several different forms are found in pathological conditions, 

 the M. pyogenes var. aureus is by far the most frequent, and it is described 

 here as a type. 



M. pyogenes var. aureus is a spherical coccus about .-jfj. to .9/4 in diameter though 

 forms -4fjL to i.2/z have been noted. On solid media the organism may be found 

 solitary, in pairs, or in rows of three or four, but characteristically in irregular groups 

 like bunches of grapes. In liquid media the single and paired arrangement is most 

 frequent. No spores, no capsules and no flagella are found; the organism shows 

 marked brownian movement, like other cocci. Gram-positive. The temperature range 

 of growth is from about 10 to 43 with an optimum about 30. Aerobe and facultative 

 anaerobe. It grows readily on all routine media, preferring a reaction slightly alkaline 

 to litmus. Growth on plain agar is rapid and abundant. After twenty-four hours 

 there appear round grayish-white or yellowish colonies about 2 mm. in diameter, 

 smooth and raised above the surface of the medium. Microscopically, the colonies are 

 regular in outline and finely granular. The characteristic orange-yellow pigment may 

 not appear until later or if already present in twenty-four hours, deepens with further 

 growth. In broth, growth is also rapid and causes a diffuse clouding with a thin pellicle 

 and a heavy sediment after several days. In gelatin, colonies are as on agar and sink 

 into cup-like depressions as the medium is liquefied. Liquefaction is rapid with some 

 strains and slower with others, and in old cultures is of a funnel or saccate type. It is 



* Prepared by Edward Fidlar. 



