FAMILY CORYNEBACTERIACEAE 



385 



grows with dark gray, daisy-head colo- 

 nies; ferments dextrin, starch and glyco- 

 gen ; is not hemolytic ; has very few small 

 metachromatic granules ; forms a pellicle, 

 granular deposit and there is an early 

 reversal of pH in broth. 



Corynebacterium diphtheriae type mitis 

 grows in convex, black, shiny, entire 

 colonies; no fermentation of starch and 

 glycogen and is variable with dextrin ; 

 hemolytic ; metachromatic granules are 

 prominent; diffuse turbidity, infrequent 

 pellicle and there is a late reversal of pH 

 in broth. 



Corynebacterium diphtheriae type m- 

 termedius grows a small, flat, umbonate 

 colony with a black center and slightly 

 crenated periphery ; not hemolytic ; bar- 

 ring of bacilli is accentuated ; there is no 

 fermentation of starch and glycogen, and 

 is variable with dextrin ; forms no pellicle, 

 a fine granular deposit and there is no 

 reversal of pH in broth. 



Ten years of observations in all parts 

 of the world have shown (McLeod, Bact. 

 Rev., 7, 1943, 1) that a small percentage 

 of strains does not correspond closely to 

 any of these three types. Variant strains 

 are found most frequently in regions 

 where the diphtheria is of mild or moder- 

 ate severity. 



Aerobic, facultative. 



Optimum temperature 34° to 36°C. 

 Grows well at 37°C. 



Source : Commonly from membranes in 

 the pharynx, larynx, trachea and nose 

 in human diphtheria ; from the seemingly 

 healthy pharynx and nose in carriers ; 

 occasionally from the conjunctiva and 

 infected superficial wounds. Found oc- 

 casionally infecting the nasal passages 

 and wounds in horses. Has been de- 

 scribed from natural diseases in fowl. 



Habitat : The cause of diphtheria in 

 man. Pathogenic to guinea pigs, kittens 

 and rabbits. For action on other animals 

 see Andrews et al . , Diphtheria. London , 

 1923, 170 ff. 



2. Corynebacterium pseudodiphtherit- 



icum Lehmann and Neumann. (Bacillus 

 der pseudodiphtherie, Loeffler, Cent. f. 

 Bakt., £, 1887, 105; G. von Hofmann- 

 Wellenhof, Wien. med. Wochenschr., 

 38, 1888, 65; Lehmann and Neumann, 

 Bakt. Diag., 1 Aufl., 2, 1896, 361 ; Bacillus 

 pseudodiphthericus ICruse, in Flligge, 

 Die Mikroorganismen, 3 Aufl., 2, 1896, 

 476; Bacterium pseudodiphtheriticum 

 Migula, Syst. d. Bakt., 2, 1900, 

 503; Mycobacterium pseudodiphthericum 

 Chester, Man. Determ. Bact., 1901, 355; 

 Bacillus hoffmanii (sic) Holland, Jour. 

 Bact., 5, 1920, 218; Corynebacterium 

 hoffmanii (sic) Holland, ibid., 220; 

 Corynebacterium pseudodiphtheriae Hol- 

 land, ibid.; Corynebacterium pseudodiph- 

 thericum Bergey et al., Manual, 2nd ed., 

 1925, 393.) From Greek pseudiis, a 

 falsehood; M. L., the disease diphtheria. 



Common name : Pseudodiphtheria ba- 

 cillus or Hofmann's bacillus. 



Excellent historical discussions of this 

 and related organisms are given by Ber- 

 gey, Comparative Studies upon the 

 Pseudo-diphtheria or Hofmann's Ba- 

 cillus, the Xerosis Bacillus, and the 

 Loeffler Bacillus. Contrib. from Lab. of 

 Hyg., Univ. of Penn., No. 2, 1898, 19-54 

 and by Andrewes et al., Diphtheria. 

 London, 1923, 382-388. 



Rods, with rounded ends, 0.3 to 0.5 by 

 0.8 to 1.5 microns, fairly uniform in 

 size, without swollen ends. Not barred 

 but even staining interrupted by trans- 

 verse, medial unstained septum ; granules 

 usually absent. Non-motile. Gram- 

 positive. 



Gelatin colonies: Small, grayish to 

 cream-colored, smooth, homogeneous, 

 entire. 



Gelatin stab : Slight surface growth 

 with little growth in stab. No liquefac- 

 tion. 



Agar colonies : Opaque, grayish to 

 cream-colored, smooth, homogeneous, en- 

 tire. 



Agar slant : Moist, smooth, white to 

 cream-colored, entire growth. 



LoefHer's blood serum : As on agar. 



