CHAPTER 25 



STAPHYLOCOCCUS, MICROCOCCUS, SARCINA, RHODOCOCCUS, AND 



LEUCONOSTOC 



STAPHYLOCOCCUS 



Definition. — Staphylococcus. 



Spherical or ovoid, non-motile, Gram-positive cells, arranged in grape-like 

 clusters on solid media, and in pairs, small groups, or short chains in liquid media. 

 On agar the growth is of a golden, white, or yellow colour. Great variation in 

 biochemical activities, hsemolytic power, and pathogenicity. Actual or potential 

 parasites. 



Type species is Staphylococcus aureus Rosenbach. 



History. — The presence of micrococci in pus was noted by Koch in 1878 ; 

 they were cultivated in a liquid medium by Pasteur in 1880 ; they were shown 

 by Ogston in 1881 to be constantly present in acute and chronic abscesses ; they 

 were cultivated by him in eggs, and were found to be pathogenic to mice and 

 guinea-pigs ; but it was left to Rosenbach in 1884 to make a thorough study of 

 the staphylococci, to obtain pure cultures on solid media, and to divide them 

 into two species — Staphylococcus pyogenes aureus and Staphylococcus pyogenes 

 albus. In the following year Passet (1885) added another species — Staphylococcus 

 pyogenes citreus. In 1887 Biondi isolated two types from saliva, both pathogenic 

 for laboratory animals ; one of these was apparently identical with an organism 

 described as M. tetragenus by Koch and Gaffky (Gaffky 1883), who had found it 

 in the sputum of patients suiJering from pulmonary tuberculosis ; the other was 

 distinguished from Staphylococcus aureus by its diminutive size— 0-3-0-5 fi in 

 diameter — and the slowness with which it liquefied gelatin ; to this he gave the 

 name of Staphylococcus salivarius pyogenes. Welch (1891) noticed a white staphy- 

 lococcus in stitch abscesses following the suturing of operation wounds ; this he 

 called the Staphylococcus epidermidis albus. Andrewes and Gordon (1905-6), who 

 investigated a large number of cocci from different sources, found a special type 

 commonly present in saliva which they named the Staphylococcus salivarius ; 

 this differed in many respects from the Staphylococcus salivarius pyogenes of Biondi ; 

 they also found a coccus of peculiar characteristics present in scurf, but did 

 not identify it by a special name. Winslow and Rogers (1906), in an attempt 

 to arrive at a classification on a statistical basis, conducted a painstaking investi- 

 gation into the CoccacecE, and proposed a division into six genera, from which the 

 original genus Staphylococcus was omitted. Later, however, Winslow, Rothberg 

 and Parsons (1920) modified this classification, and reinstated the Staphylococcus 

 in its old place, dividing the genus into six species. 



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