STREPTOCOCCIC INFECTION 157 



the reverse may be true. This was suspected long before we had any 

 definite knowledge of bacteria. The village doctor of that time knew 

 that it was not a wise thing to attend a childbirth while he had patients 

 with erysipelas or scarlet fever, or while he was dressing infected 

 wounds. This indefinite knowledge of that time has been defined 

 by experiments. Erysipelas has been induced experimentally with 

 matter taken from wounds, from throats in angina, and from the 

 uterus in puerperal fever. All these and many other diseases are due 

 to the same organism and are mutually convertible one into another. 



When the infection lies deeper and in the subcutaneous tissue, 

 diffuse phlegmon and widely extended abscesses with extensive 

 destructive changes result. With the infection in the larger lymph 

 vessels, lymphangitis and lymphadenitis occur. In these either the 

 streptococcus or the staphylococcus, or both, may be found. Other 

 skin affections due to the pus bacteria are acne, impetigo, erythema 

 and infectious purpura. From infected wounds a scarlatinous rash 

 may extend over the greater part of the body, and may lead to arthritis 

 and nephritis. 



The streptococcus is frequently found in every part of the respira- 

 tory passages and it seems to play an important role in various inflam- 

 matory diseases of these parts. Whether the normal residents of these 

 surfaces become suddenly virulent or more virulent strains are intro- 

 duced, is not always easily determined. The streptococcic sore throat, 

 which has in recent years occurred in epidemic form and proved so 

 highly fatal, is believed to be due to the use of milk containing highly 

 virulent strains. There are reasons for believing that the essential, if 

 not the sole, causal factor in scarlet fever is a streptococcus. This 

 organism is found constantly in otitis media. Malignant endocarditis 

 and polyarthritis are due to virulent strains of the streptococcus. 

 Streptococcic pneumonia is recognized and may run either an acute or 

 a chronic course. The latter may resemble typhoid fever and the 

 intensity of the general symptoms may be out of proportion to the 

 physical, local findings. Purulent pleurisy is not rare. The part taken 

 by the streptococcus in the etiology of the summer diarrheas of infancy 

 seems to be important and market milk often contains virulent strains 

 of this organism. In inflammatory diseases of the udders of cows, 

 highly active strains of the streptococcus find their way into the milk. 



