480 FUSIFORMIS 



cultures of the organism from the mice. He classed it with the Streptothrix group under 

 the Leptothrix or Cladotlirix genera, and called it Streptothrix cuniculi. The organism 

 has been described by a few other workers. (For a detailed description of it, see Orcutt 

 1930, Beveridge 1934.) HaUe (1898) named a bacillus associated with genital infections 

 in man B. funduliformis, and later Teissier and his colleagues (Teissier et al. 1929, 1931) 

 found the same organism in fovu: cases of septicaemia in man. It probably corresponds 

 to the species C described by VeiUon and Zuber (1898) and its role in putrid infections 

 of man has been confirmed by a number of workers (see Chapter 79). The human strains 

 do not differ in any consistent way from the animal strains of F. necrophorus, except 

 that they are usually less pathogenic for laboratory animals (Dack, Dragstedt and Heinz 

 1937) and tend to be pleomorphic. 



Morphology. — In the diphtheritic membrane of calves, the bacilh appear as long 

 threads — 5 to 6 times as long as they are broad — arranged either in thick heaps or 

 in long wavy rows. In the pleural or pericardial exudate ol rablats dying of labial necrosis 

 they usually appear as Gram-negative, highly pleomorphic baciUi, varying in shape from 

 cocci to bacilli and long threads. In the thread forms there are often oval unstained 

 portions arranged at regular intervals, looking like spores ; but as they do not give the 

 differential spore stain and are not particularly resistant to heat, they cannot be regarded 

 as spores. The filaments may reach 80-100 /.i in length ; they are 0-75-1 -5 p, thick ; one 

 end is often narrow and pointed, the other thicker or almost fusiform. They may be 

 surrounded by a capsular material. Branchhig does not occvu-. In culture the organisms 

 appear as straight or curved rods, or as filaments. The ends are rounded, and the sides 

 are generally parallel, though fusiform enlargements, including " ball " forms up to 

 5/i in diameter, are not uncommon. Except in young cultures, staining is irregular, 

 and beaded forms are common. 



Cultivation. — Schmorl cultivated the organism in deep inspissated sheep serum. It 

 grows only under anaerobic conditions. Deep colonies in serum agar plates are round, 

 pinhead in size, matt-white, with an entire edge ; under a low power they have a thicker 

 centre and an irregularly radiate periphery ; under a liigh power the centre consists of 

 a mesh-work of threads, and the periphery of streaming threads, which pass often for some 

 distance into the surrounding medium. According to Shaw (1933), deep colonies in a 

 semi-solid glucose serum agar medium have a grey, cotton-like, fluify appearance, while 

 in stiifer agar they are brown, circular or biconvex, with an entire edge. Surface colonies, 

 after 2 days on a special serum agar medium (V.F.), made up with a peptic digest of ox 

 muscle and liver, are circular, convex, about 1 mm. in diameter, almost water-clear, and 

 glistening ; after 7 days they are differentiated into a convex centre and a narrow flat 

 periphery with a slightly dentate edge ; they are butyrous in consistency and easUy emiilsi- 

 fied (Beveridge 1934). In V.F. broth there is a dense turbidity, with a small dirty-white 

 deposit, which increases as the medium clears on further incubation. Stab growth in serum 

 begins in 24 to 40 hours near the bottom of the tube, and spreads upwards to within |-1 cm. 

 of the surface ; the growth is filiform with radiate branches ; the serum is partly clouded, 

 but not liquefied. There is no growth on potato. In glucose agar, Schmorl obtained 

 growth only in the presence of a coccus. He quotes this as an example of metahiosis — 

 or the abUity of one organism to grow in a particular medium only when another organism 

 has prepared the medium for it, and rendered it suitable. V.F. gelatin (see above) is not 

 liquefied. Turbidity and vigorous gas production occur in cooked heart medium and 

 brain medium. A zone of haemolysis, about 0-5 mm. wide, is said to surround deep colonies 

 in blood agar plates. Broth containing 10 per cent, of serum and a reducing agent like 

 cysteine (0-1 per cent.) may support growth (Dack et al. 1938). Cultures, especially in 

 Uquid media, have a foul odour. Growth occurs between 30° and 40° C, with an optimum 

 at 37° C. 



Biochemical and Metabolic. — Gas, and a variable amount of acid, are produced 

 in glucose, maltose and Isevulose. Fermentation of glycerol, galactose and sucrose is 



