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BACTERIOLOGY FOR NURSES 



tions already referred to ; a few rare cases are on record in which 

 it has been cited as the sole producer of a pyogenic condition. 



STREPTOCOCCI 



The pathogenic streptococci were first discovered by Koch in 

 stained sections of diseased tissue, and by Ogston in 1881 in the 

 pus of acute abscesses. Later in 1883 Fehleisen obtained pure 

 cultures from a case of erysipelas. Because of the variety of 

 pathologic conditions in which streptococci were found it was at 

 first thought that each was produced by a different species ; now 

 it is generally assumed that the slight differences between the 



streptococci of erysipelas, 1 of 

 acute abscesses, of septicemia, 

 of puerperal fever, etc., are 

 only acquired variations of 

 organisms of the same spe- 

 cies. 



All spherical bacteria which 

 divide in one plane only and 

 remain attached in longer or 

 shorter chains, resembling 

 somewhat a string of beads, 

 are classified together under 

 the name of streptococci (Fig. 

 42). The classification is simply a morphological one and includes 

 both saprophytic and parasitic varieties. The relationship be- 

 tween the streptococci from different sources is by no means clear. 

 Those of greatest importance, however, because of the power 

 which they possess of inciting disease in man and because such 

 diseases are frequently of a suppurative character, are roughly 

 grouped together as streptococcus pyogenes. 



Streptococcus pyogenes. Morphology and Staining. The cocci 

 are relatively small, measuring from 0.5 micron to 1 micron in 

 diameter ; they have no flagella nor do they produce spores. As a 

 rule the pathogenic streptococci show a tendency to remain united 



FIQ. 24. Streptococci. 



