TREPONEMA PALLIDUM 



915 



invasive properties (Ellermann 1907). It is very frequently found in association with a 

 characteristic fusiform bacillus, likewise described by Vincent (1896, see Chapter 18). 

 It has been suggested (Tunnicliff 1906) that Trep. vincenti and the fusiform bacillus 

 represent two phases of the same organism ; but the balance of evidence is definitely 

 against this view. 



Treponema pallidum 



Isolation. — Described by Schaudinn and Hoffmann (1905), who observed it in chancres 

 and inguinal glands of syphilitic patients (see Schuberg and Schlossberger 1930). 



Morphology. — Thin, delicate spirochsete with tapering ends. Its length varies from 4-14 

 [X, and its breadth is about 0-2 //. It contains a number of regular primary spirals, which 

 appear rather sharp and angular, and each of which is a little over 1 /z in length. During 

 motion secondary curves may appear and disappear in rapid succession, but the primary 

 spirals remain undisturbed. The organism is actively motile ; the movements were origin- 

 ally described by Schaudinn and Hoffmann (1905) as being of 3 types: (1) rotation round 



Fig. 216. — Electron microt;raph of Tn p<jnt ma pitUidiini. showing what ajipear to be flagella 

 (X 21,000). [Kindly supplied by Dr. Stuart Mudd.] 



the longitudinal axis ; (2) backward and forward movements ; (3) flexion movements 

 of the whole body, resulting in the production of secondary waves. The rotation 

 or spinning movement is responsible for the backward or forward movements ; the 

 primary spu-als act Hke the blades of a propeller and drive the organism forward. No 

 flagella can be demonstrated by ordinary methods, but according to Mudd, Polevitzky 

 and Anderson (1943) and Wile and Kearney (1943) flagella, often four in number, may 

 be seen in electron micrographs distributed along the sides or near the ends of the organism. 

 In cultures the morphology is not so regular as in the animal body ; Noguchi (1912c) 

 has described three types of pallidum — the thicker, the normal, and the thinner type. 

 Whether these types are constant, or merely represent fluctuations round a mean, is 

 not known ; Noguchi favours the former view. The organism stains rose-red with Giemsa. 

 The organisms are held back by gradocol membranes having a pore size of 0-4 p, ; their 

 narrowest diameter is therefore about 0-2 p (Hindle and ELford 1933, Tilden 1937). 



Cultivation. — ^Schereschewsky (1909) was the first to cultivate Trep. pallidum in vitro, 

 but he did not succeed in obtaining pure cultures. Noguchi in 191 1 was the first to do this. 

 He used a medium of serum water to which a piece of sterile rabbit tissue had been added ; 



