40 



Scientific Proceedings (95). 



24 (i399) 



Experimental pneumonia produced by Streptococcus hemolyticus. 



By Martha Wollstein and S. J. Meltzer. 



[From the Laboratories of the Rockefeller Institute for Medical 

 Research, New York.] 



Pulmonary lesions were produced by the insufflation of a strain 

 of Streptococcus hemolyticus isolated in Texas and kindly given us 

 by Dr. Avery. The cultures proved to be highly virulent for 

 white mice. A quantity of the culture was insufflated intra- 

 bronchially into twenty-four dogs. The dose varied from I to 3 

 c.c. per kilo. Of these animals nine died in less than twenty-four 

 hours, one died on the third day, and the rest were killed three to 

 fifteen days after the inoculation. Dogs which survived more 

 than two days went on to recovery, although they were ill for 

 several days. Streptococcemia was found in all the animals which 

 died early. It was also found in one of two dogs which was killed 

 on the third day and in one of two killed on the fourth day after 

 injection. Later than the fourth day no streptococci were found 

 in the blood. Blood stained pus was present in the pleural cavity 

 in three dogs, all having streptococci in the heart's blood. One of 

 these animals died on the third day, one was killed on the third 

 day and one on the fourth day. In the rest the pleura was normal. 

 Empyema seemed to have developed before the third day. 



The pneumonic lesion, in its early stage (twenty-four hours 

 after injection), consisted of intense congestion, edema and small 

 hemorrhages without pleurisy. After forty-eight hours the con- 

 gestion and edema were still more marked and areas of broncho- 

 pneumonia had developed. The solid areas coalesced to some 

 extent, but never became massive. The lungs in these dogs, even 

 on the third day, were never very solid. The lesions involved 

 usually more than one lobe. Resolution had begun on the fourth 

 day, but in one instance there was a distinctly solid area of broncho- 

 pneumonia present on the seventh day. In the second week only 

 areas of darker color were left. In no case had organization 

 occurred. 



Cultures from the lungs gave streptococci on the first, second, 

 third and fourth days, but remained sterile on the fifth and sixth 



