472 CORYNEBACTERIVM 



ferment lactose. Of 2 strains examined by Siidmersen and Thompson, one actively fer- 

 mented saccharose, the other gave a late and slight acidity. In our experience acid is 

 generally formed in glucose, maltose, and sucrose, sometimes in lactose, but not in maimitol. 

 SUght acid in litmus mUk. Indole negative. Nitrates reduced. Gelatin not liquefied. 



Antigenic Structure. — According to Craddock (1942) two types can be distinguished 

 by agglutination with specific rabbit sera. 



Pathogenicity and Toxin Production. — It is generally believed that C. acnes is 

 jetiologically related to the lesions from which it has been isolated. Experimentally it 

 shows some degree of pathogenicity for the mouse. 



C. typhi 



Isolated by Plotz ( 1914) from the blood of patients suffering from typhus fever. Origin- 

 ally regarded by Plotz and his colleagues as setiologically related to the disease (Plotz, 

 Olitsky and Baehr 1915), but now generally admitted to be an example of a parasitic 

 microaerophilic diphtheroid, without any established pathological significance (Olitsky 

 1921). 



Morphology is that of a small pleomorphic diphtheroid, with few elongated cells 

 but numerous coccal forms. The rod-forms which occur may be straight or curved, with 

 rounded or pointed ends. Metachromatic granules are present. 



Growth. — C. typhi appears to demand more strictly anaerobic conditions for growth 

 than C. acnes ; but there appears to be no record of the result of acidification of the medium. 

 It is recorded as giving a creamy-white growth on Loefflor's serum, glucose serum agar, 

 or potato ; the growth takes on a light brown colour in its later stages on the latter 

 medium. 



Biochemical Reactions. — Tested on ascitic agar containing 2 per cent, of the test 

 carbohydrate, and incubated in Buchner tubes, C. typhi is stated to produce acid from 

 glucose, maltose, and galactose, but not from mannitol, dextrin, lactose or saccharose. 



Antigenic Structure unknown. 



Pathogenicity. — Probably shght or absent. 



We append, in tabular form (Table 31), the chief differential character- 

 istics of the ten named species described above, and the fermentation reactions 

 of the eleven groups of diphtheroid bacilli differentiated by the Committee of the 

 Medical Eesearch Council (Table 32). In both tables the + sign signifies the 

 formation of acid. Since the fermentation reactions of this group are habitually 

 tested in Hiss's serum-water medium, the formation of acid will usually be followed 

 by the formation of a clot, after a longer or shorter period, though some strains 

 which produce definite acidity in the presence of a particular carbohydrate fail to 

 clot the medium. 



With regard to the eleven groups of unnamed diphtheroids, the Committee note 

 that there is no correlation between the source from which any strain was derived 

 and its biochemical reactions. Thus, of the 15 strains which fall into Group I, 

 ten came from the nose, one from the ear, two from the eye, one from an infected 

 wound, and one from a specimen of pus. As already noted, there was no consistent 

 relation between pigment production and fermentative activity. Thus one strain 

 of Groups IV, VII and XI produced pigment, as did the single representative of 

 Group IX. The four strains of Group VI, on the other hand, and the three strains 

 of Group VIII all formed pigment ; so that these two groups would appear to be 

 characterized by a marked tendency to pigment production. It may be noted 

 that none of the strains examined produced the pink or red pigments which have 



