VARIETIES OF STREPTOCOCCI 207 



variety as the streptococcus mitis does to the streptococcus pyogenes. It 

 ferments saccharose, lactose, and raffiuose, sometimes the glucosides and 

 ruivly inulin ; it cl<>cs milk and reduces neutral-red. (d> Tlie strepto- 

 coccus iiiKjiiuHtHS, wnicli corresponds with the so-called streptococcus 

 searlatime and the streptococcus conglomeratus. It ferments saccharose 

 and lactose, and sometimes ratfinose, reduces neutral-red, and is actively 

 hiumolytic. It us .ally clots milk and does not grow on gelatin at 20 C. 

 (e) The xti-i'iitiicuccns fcecalis, a. short-chained form, which abounds in the 

 inte-tine and which has great fermentative activity, and reacts positively 

 t-> all Gordon's tests with the exception of raffinose and inulin. It forms 

 sulphuretted i-ydropen, and is devoid f haemolytic action. (/) The 

 sixth variety is the streptococcus equiims. which is common in the air and 

 dust of t"wns, and appears to be derived from horse dung. 1 It fernu-nts 

 saccharose and the two glucosides. and forms little or no ncid in milk. It 

 is, ho\vev.-r, to be noted that t> all these varieties variants are met with. 

 Schottmiiller has employed the appearance of the colonies of strepto- 

 cocci on blood agir as a means of separating varieties, the medium used 

 cou.-isting of i wo parts human blood and live parts melted agar. He 

 distinguishes the streptoroccu* lonyus or erysipclatis, which forms grey 

 colonies and has a marked luemolytic action ; a streptococcus mitior or 

 viridan-s, a short-chained organism, which produces small green colonies 

 and very little haemolysis ; and a streptococcus muco us encapsulates, 

 which, as its name indicates, shows wall-marked capsules and produces 

 colonies which have a slimy consistence. Mandelbaum adds to these the 

 streptococcus saprojthyticus, which is without haemoiytic action. It should 

 be noted that on blood agar the pneumococcus forms green colonies and 

 1 .K.I luces little r no haemolysis. Levy finds that a 2 '5 per cent, solu- 

 ti >n of taurocholate of sodium in bouillon produces complete bacterio- 

 lysis of the pneumococcus and the streptococcus mucosus, while it has 

 no effect on other varieties of streptococcus. He considers the strepto- 

 coccus mucosus to lie a variety of pneumococcus. The general statement 

 may be made that most of the streptococci from lesions in the human 

 subject have hsemolytic action, but that occasionally streptococci without 

 this property are found even in severe infections. 



It will be thus seen from this account that the streptococcus 

 pyogenes as described above is the organism most frequently 

 associated with the pathogenic processes, and that short-chained 

 forms are common saprophytes in the. human body, although 

 they may be associated with conditions of disease ; these may 

 be subdivided according to their fermentative activity as 

 detailed. And lastly, there is the streptococcus conglomeratus 

 (anginosus), which is specially abundant in the throat in scarlet 

 fever, though it also occurs in other acute catarrhal states. No 

 definite statement can yet be made as to the etiological relation 

 of streptococci to scarlet fever ; we can only say that streptococci 

 are almost invariably present in the fauces, and that to them 

 many of the complications of the disease are due. 



1 For further details, reference must be made to the original papers, Lancet, 

 September 1906, ii. 708, etc. 



