Pathogenic Streptococci and Milk Pasteurization.

D URING the investigation of a recent epidemic of septic sore throat' the writers of this article ook occasion to make a fairly extensive .urvey of the literature of the strepto:occi with special reference to their relaion to the spread of disease through milk. Che results of this survey, together with :ertain observations made in the course of he investigation, have impressed us with he fact that streptococci should be given pecial consideration in connection with he subject of milk pasteurization. It is a well known fact that the ternterature and time of heating necessary to .ompletely sterilize a suspension of baceria is affected not only by the specific teat resistance of the organism used but Is° by the number or concentration of he organisms in the suspension. As was Jointed out by Phelps2 the rate of killing t a given temperature follows the Jgarithmic curve of the physicochemical ,elocity laws. That certain factors reitted to the nature of the suspension may Ilso affect the thermal death rate appears vident from the results of some experihents described below. It is the purpose of milk pasteurization, ,f course, to destroy by heating all of the iathogenic bacteria that may be present h the raw product. It is desirable that he temperature and the time of heating hall be kept as low as possible because .f certain alterations in the milk due to leat. These changes are principally those Iffecting the cream line, the taste and the itamin content. To some extent these ffects bring pasteurization into conflict