314 AGEICULTUKAL AND INDUSTRIAL BACTERIOLOGY 



lying just behind the ear, causing the condition known as 

 mastoiditis. The latter condition is particularly dangerous 

 because of the possibility eventually of the organism passing 

 through the bony inner wall of the mastoid, gaining access 

 to the brain cavity and there causing inflammation of the 

 covering membranes of the brain and spinal cord or 

 meningitis. Surgical intervention is sometimes necessary. 



Organisms of this type may also cause ulcer ation of teeth 

 and in improperly filled teeth the organisms may pass 

 through the root, gain access to the gums and cause chronic 

 inflammation (or pyorrhea) about the roots of the teeth, in 

 some cases leading to a more diffused inflammation usually 

 termed gingivitis or inflammation of the gum. The mucous 

 membranes lining the nose may also be inflamed by organ- 

 isms belonging to this group, giving rise to the condition 

 known as rhinitis or more commonly as a cold. From these 

 membranes the organism sometimes passes by means of the 

 connecting canals into the sinuses of the head, that is, into 

 those cavities in the bones lined by mucous membranes. 

 Among the more important of these are the frontal sinuses. 

 This condition is known as a sinusitis. Inflammation of the 

 udder sometimes occurs in cattle as a result of infection 

 with organisms of this general type, producing the condi- 

 tion known as mastitis or garget. Erysipelas in man appar- 

 ently is due to the growth of this organism in subcutaneous 

 tissues producing extensive or general inflammation. 



In some cases a focal infection with a highly virulent 

 organism may lead to the passage of the organism to the 

 blood stream and the development of septicemia (or "blood 

 poisoning"). Certain types of pneumonia, particularly 

 many following influenza, are due to infection of the lungs 

 from highly virulent strains of streptococci. Streptococcus 

 infection is not uncommon in lower animals. Such, for 

 example, is the so-called navel ill of the colt. The organism 

 enters through the umbilicus soon after birth. Wound 



