PATHOGENIC BACTERIA. 



123 



FIG. 69. 



Form. Micrococci in clusters like bunched grapes, hence the 

 name staphylo, which means grape. They never form chains. 

 Spores have not been found, though the cocci are very resistant. 



Properties. Without movement ; liquefying gelatine. It gives 

 rise to an orange-yellow pigment in the various cultures. 



Growth. It grows moderately fast at ordinary temperature, 

 and can live without air, a facultative serobin and anierobin. 



Colonies on Gelatine. On second day small dots on the surface, 

 containing in their centre an orange-yellow spot. The gelatine 

 all around the colony is liquefied ; the size is never much greater 

 than that attained the second day. 



Colonies on Agar. The pigment remains a 

 long time. 



Stab Culture. At first, gray growth along 

 the track, which, after three days, has settled 

 at the bottom of the tube in a yellow granular 

 mass, the gelatine being all liquid. 



Stroke Culture on Agar. The pigment dif- 

 fused over the surface where the growth is, in 

 moist masses. 



Potato. A thin white layer which gradu- 

 ally becomes yellow and gives out a doughy 

 smell. 



Staining. Very readily colored with ordi- 

 nary stains ; also with Gram's method. 



Pathogenesis. When rabbits are injected 

 with cultures of this microbe into the knee- 

 joint or pleura, they die in a day. If injected 

 subcutaneously, only a local action occurs, 

 namely, abscesses. 



If directly into circulation, a general phleg- 

 monous condition arises, the capillaries become 

 plugged with masses of cocci, infarct occur in kidney and liver, 

 and metastatic abscesses form in viscera and joints. Garre, by 

 rubbing the culture on his forearm, caused carbuncles to appear. 



Fracturing a long bone in an animal and then injecting the 

 staphylococcus into a large vein, as the jugular, will produce 

 osteomyelitis. Becker isolated this microbe from several cases 



Stab culture. Micro- 

 coccus pyogenes 



