482 



FUSIFORM IS 



is little evidence of the presence of a soluble substance of the exotoxin type (Scrivner 

 and Lee 1934). 



F. fusiformis. — This organism was first described by Vincent in 1896, who found it 

 frequently associated with Trep. vincenti (see Chapter 38) in necrotic and ulcerative 

 lesions of the throat and other tissues. A similar, and possibly 

 identical, organism was observed by Veillon and Zuber (1898) 

 in appendicitis and other necrotic lesions of man, and named 

 by them B. fusiformis. Smith (1933) has recorded its presence 

 in tropical ulcer. In necrotic tissue the organisms appear as 

 long rods, 5-12 /i in length, thickened in the middle, and with 

 tapering or pointed ends. The axis is straight or curved. They 

 are arranged singly or in pairs end-to-end, and are non-motile. 

 They stain readily with the usual aniline dyes, and are Gram- 

 positive, but are decolorized if the treatment with alcohol is 

 prolonged. In cultures the bacilli are pleomorphic (Leukowicz 

 1906) ; they vary greatly in size, and do not always show the 

 typical fusiform shape. Long filamentous forms are common. 

 The various morphological types of fusiform bacilU (see above) 

 cultivated from the normal mouth of man and animals vary 

 from thin, slightly pointed bacilli 0-4 X 3-5 /n, to long and thick 

 shghtly pointed bacilh, 0-7 x 6-25 /^. TunnicUff (1923, 1933) 

 considered the spirillar forms found in association with fusiform 

 bacUh in lesions of the throat to be a phase of the fusiform 

 type ; and found that spiral forms were relatively common in 

 " rough " variants of fusiform bacilH. Hine (1937) considers 

 that there is no good evidence of a genetic relationship between 

 fusiform bacilli and spirochsetes. 



The serological grouping of fusiform baciUi made by Rettger 

 and his colleagues has been noted above. Bachmann and 

 Gregor (1936) found two groups in mouth strains, correspond- 

 ing respectively to filamentous, odour-producing bacilli associ- 

 ated with stomatitis, and to short diphtheroid bacUU, 

 producing no odour in culture, found in healthy mouths. 

 The organism can be cultivated under anaerobic con- 

 ditions at 37° C, but not at room temperature, in serum 

 agar or serum broth. The deep colonies appear in 2 

 days, and are 1-1 J mm. in diameter. The smallest 

 colonies have a felt-like, branched appearance ; the 

 larger ones are round ; and the largest of all are pris- 

 matic with angled projections, and are of a yellowish 

 colour. On the surface of serum agar, the colonies are 

 small and resemble those of streptococci, but on 

 further incubation they may show a considerable peri- 

 pheral extension, and come to resemble colonies of 

 CI. sporogenes (see p. 876). In serum broth, large white 

 flocculi form in 24 hours, and later sink to the bottom 

 (Ellermann 1904) (see Fig. 89). On plain agar there 

 may be no growth at all, or a thin, very delicate whitish 

 layer limited to the line of inoculation may develop 

 after 48 hours (Weaver and Tunniclifif 1905). LoeflSer's serum and Dorset's egg medium 

 are both suitable. Neither is liquefied. Growth does not occur in media containing 

 sugar, unless blood or ascitic fluid is added. Peters (1911) found that, in the presence 

 of rabbit blood, acid was produced in glucose, maltose, mannitol, and lactose, but not 

 in sucrose ; there was no indole formation. Group I organisms of Spaulding and Rettger's 



Fig. 89. — Fusiformis 

 fusiformis. 



Blood broth culture an- 

 aerobically, 3 days, 

 37° C. showing floc- 

 cular growth. 



Fig. 90. — Fusiformis fusi- 

 formis. 



Surface colony on serum agar, 

 anaerobically, 7 days, 37° C. 

 ( X 8). Resembles Slanetz 

 and Rettger's Type IV. 



