946 THE PLEUROPNEUMONIA GROUP OF ORGANISMS 



reduction of haemoglobin result from the growth of some strains. Antigenically 

 there is a considerable degree of specificity, though there is evidence of some group 

 relationship among many of the members that have been studied (Klieneberger 

 1940). The parasitic species often seem to lead a harmless commensal existence 

 in the body of their host, though under certain conditions they may give rise to 

 lesions of various types, of which arthritis is one of the commonest. At least 

 one species, L5, forms an exotoxin acting on the central nervous system. Virulence 

 is apt to decline rapidly in artificial culture. Pathogenicity is limited usually 

 to a single host species. Some members are susceptible in the tissues to organic 

 gold salts (Collier 1939a, Findlay et al. 1939). 



The saprophytic species, isolated from sewage, earth, and other situations, 

 differ from the parasitic species mainly in their simpler growth requirements — a 

 high proportion of animal protein being unnecessary for their development — in 

 their ability to multij)ly at 22° C, in their antigenic structure, and in their absence 

 of pathogenicity. We append brief notes on some of the commoner strains. 



Pleuropneumonia Strains in Dogs. 



Shoetensack (1934) isolated in pure culture an organism, sometimes referred to as 

 Asterococcus canis, from nasal secretion, lung, and liver of dogs suffering from distemper. 

 Two antigenic types are recognized (KUeneberger 1938, 1940). The pathogenicity of 

 these strains to dogs and their relationship to distemper are in doubt. 

 Pleuropneumonia Strains in Rats. 



LI strains. — KUeneberger (1935) described the isolation of a pleuropneumonia-Iike 

 organism from cultures of Streptobacillus moniliformis, which is a normal parasite of the 

 nasopharynx of rats (see p. 385). She ob tamed it in pure culture, and showed that it 

 had the same colony type, characterized by a central granular part embedded in the 

 agar medium and a flatter peripheral zone, as the organism of pleuropneumonia. It was 

 filtrable through Berkefeld V candles. By itself it appeared to be non-pathogenic. From 

 the lung of one rat it was isolated independently of Streptobacillus moniliformis (KUene- 

 berger 1938). Though KUeneberger maintained that it was a symbiont, Dienes (1939, 

 1942), Heilman (1941), Smith (1941), and Brown and Nunemaker (1942), regard it as 

 a variant of the bacUlary organism. KUeneberger's (1942) most recent observations 

 bring further evidence in favom* of the symbiotic view. She shows that the develop- 

 mental cycle of the LI organism appears to be almost identical with that of the organism 

 of pleuropneumonia as described by KUeneberger and Smiles (1942) ; and that the results 

 of cross-absorption tests made between Streptobacillus moniliformis and LI are most easUy 

 expUcable on the assumption that the two organisms are antigenicaUy distinct. 



L3 strains. — KUeneberger and Steabben (1937) isolated this organism from the bronchi- 

 ectatic lesions that are so common in the lungs of old rats. It is antigenicaUy distinct 

 from LI (KUeneberger 1940). Though abscess formation results from subcutaneous 

 inoculation of pure cultm-es into half-grown mice, it has so far proved impossible to repro- 

 duce the natural disease in rats (KUeneberger and Steabben 1940). 



L4 strains. — This organism was isolated first by Woglom and Warren (1938) from 

 subcutaneous abscesses in rats following inoculation with a rat sarcoma strain. Its 

 relation to the pleuropneumonia group was not recognized till, later in the same year, 

 KUeneberger (1938) reported the isolation of an organism, which she caUed L4, from 

 the swoUen submaxUlary gland of a rat. It is antigenicaUy distinct from LI or L3. When 

 inoculated subcutaneously or intraperitoneaUy into rats, it gives rise to abscess formation. 

 Inoculated intravenously with ceUs or agar it produces a severe arthritis, particularly 

 in young rats. An organism, labeUed L7, was isolated by Findlay, Mackenzie, MacCaUum, 

 and Klieneberger (1939) from spontaneous polyarthritis in the rat, but this organism 

 was later shown by KUeneberger (1939a) to be identical with L4. Its relation to the 

 organisms described by CoUier (19396) and Beeuwkes and ColUer (1942), which were like- 



