718 



SCIENCE 



[N. 8. Vou XL. No. 1037 



slight differences between these streptococci and 

 the ordinary Streptococcus pyogenes, and these 

 differences have been sufficient to lead to the 

 use of the special term Streptococcus epidem- 

 icus for them. It should be stated that it may 

 be questioned whether or not the differences 

 between them and the Streptococcus pyogenes 

 are sufficient to justify such a distinction. 

 They may be simply highly virulent strains of 

 ordinary Streptococcus pyogenes whose prop- 

 erties have been modified by animal passage. 



In some of the reports, particularly the 

 earlier ones, and this is especially true of the 

 English epidemics, descriptions of the strep- 

 tococci are not given in detail. In certain in- 

 stances this could not be done because the epi- 

 demic was practically over before its study 

 was undertaken. It is unfortunate that this 

 is so, because it is very important that the or- 

 ganisms from each of these epidemics should 

 be carefully studied in order that the results 

 may be correlated. It niay not be out of 

 place here to call the attention of physicians 

 and health officials to the importance of such 

 studies. Especially should the local physicians 

 and health officers in small communities and 

 towns be on the lookout for such epidemics, 

 for it is they who meet these cases early, the 

 time most suitable naturally for the isolation 

 and study of the causative agent. Such physi- 

 cians and health officers should see to it there- 

 fore that a careful bacteriologic study be 

 undertaken as soon as possible. If they have 

 not the means at hand or for any reason do 

 not care to undertake such a detailed study, 

 they should send the material to some labora- 

 tory where this can be done. The writer would 

 be glad to examine such organisms with a 

 view to identification and requests any who 

 may desire to do so to send such material to 

 him. 



It may be stated that in the future it is 

 probable that the small community will be 

 affected by such milk epidemics more fre- 

 quently than the larger cities since the milk 

 products are apt to be less carefully handled 

 and pasteurization will less often be required 

 than in larger places. 



One of the properties noted in the strep- 



tococci from nearly aU the epidemics is that of 

 hemolyzing blood when the colonies are grown 

 on human or rabbit blood agar plates. While 

 there has been slight variations in the strains 

 studied, they have been strikingly alike in 

 this respect. By hemolysis is meant that a 

 well-defined wide clear zone appears about the 

 colonies in 24 hours at incubator temperature. 

 It does not mean a slight halo occurring about 

 the colonies nor does it mean a slight narrow 

 ring of cleared media developing perhaps after 

 48 hours or more as occurs with certain strains 

 of organisms. This property is of great im- 

 portance because it is a very ready and prac- 

 tical means of differentiating such organisms 

 from the common Streptococcus lacticus 

 (Bact. guntheri) which are not hemolytic. 

 These latter are practically always present in 

 normal milk, and so far as we know are of no 

 sanitary significance. It should be pointed 

 out that there are other perhaps more reliable 

 but less practical means of determining the 

 hemolytic power of bacteria than the simple 

 plate method. I refer to such methods as 

 those of LyalP and Marmorek^ which should 

 be used as confirmatory tests, where they are 

 of real value. 



It is not to be understood that every hemo- 

 lytic streptococcus is necessarily virulent or 

 dangerous to man. But finding them in any 

 considerable number in milk should make one 

 very suspicious of udder disease, and such 

 milk should at once be excluded from use. 



The question of the source of streptococci 

 causing these epidemics of sore throat is an 

 important one. Two possible sources are rec- 

 ognized : the one bovine — the udder or teats of 

 the cow; the other human — some lesion in the 

 throats, hands, etc., of a milker or handler. 

 It is often a difficult matter to absolutely 

 prove in a given case whether or not the infec- 

 tion is bovine or human in origin. This is 

 because practically identical hemolytic strep- 

 tococci occur in the -diseased udders of cows 

 and also in the throats and on the hands of 

 milk handlers. Furthermore, both streptococcal 

 infections of udders in cows and streptococcal 



2 Jour. Med. Research, 1914, XXX., 487. 



3 Ann. de I'Inst. Past., 1902, XVI., 172. 



