OTHER ORGANISMS OF THE PLEUROPNEUMONIA GROUP 947 



wise isolated from polyarthritis in the rat, and to the organisms cultivated by Preston 

 (1942) from the swollen joints and middle ear of rats, is still in doubt. Gold salts appear 

 to be of j^rophylaetic value in protecting against arthritis caused by the inoculation of 

 L4 into rats (CoUier 1939a, Findlay et al. 1940). 

 Pleuropneumonia Strains in Mice. 



Pleuropneumonia-hke organisms in the mouse's brain were demonstrated independently 

 by Findlay and his collaborators (1938) in this country while investigating lymphocytic 

 choriomeningitis, and by Sabin (1938) in the United States during the course of experi- 

 ments with Toxoplasma. Several other strains, biologically and immunologically distinct, 

 have since been isolated. Except in very young mice, they seem to be normal parasites 

 of the conjunctiva, nose, and brain (Sabin and Johnson 1940). 



L5 and Type A strains. — L5 was isolated by Findlay and his colleagues (1938) from 

 the brains of mice suffering from rolling disease. A similar, if not identical, organism 

 was isolated by Sabin (1938), who showed that it produced a true exotoxin having strongly 

 neurolytic properties. Intracerebral inoculation of the organism gives rise, usually after 

 an incubation period of 2-3 days, to a disease characterized by rolling movements on 

 the long axis of the body. Some mice die, and at post mortem extensive necrosis and 

 lysis are found of the posterior pole of the cerebellum. Apparently the same organisms 

 have been isolated from the lungs by SuUivan and Dienes (1939). 



L6 strains. — These strains were isolated by Findlay and his colleagues (1939) from 

 the brains of mice that had been inoculated intracerebrally with the blood of splenecto- 

 mized mice containing Eperythrozoon coccoides. They differ coloniaUy and antigenically 

 from L5 strams. 



M55 strain. — This organism was isolated from the swoUen joint of a mouse by Jahn 

 (see KUeneberger 1940). It is responsible for one type of mouse arthritis. 



B, C, D, and E strains. — These organisms were isolated by Sabin (1938, 1939a, b) 

 and by Sabin and Johnson (1940) from the conjunctiva, respiratory tract, and brain of 

 mice. All four types are able to give rise to arthritis on intravenous inoculation. What 

 relation they bear to the L6 and M55 strains is not yet known. 



Edward's strains. — Edward (1940) isolated 7 strains from the lungs of normal mice. 

 Some evidence was obtained that they might give rise to pneumonic lesions after nasal 

 instillation, but they did not produce arthritis. 

 Pleuropneumonia-like Strains in Guinea-pigs. 



The guijiea-pig so far has not been a fruitful soiurce of pleuropneumonia-Uke organisms. 

 I^eneberger (1940) isolated a strain, in conjunction with Streptobacillus moniliformis, 

 from abscesses in the neck, but circumstances prevented its proper study. Smith (1941) 

 Ukewise reported the isolation of Streptobacillus moniliformis from abscesses in guinea-pigs, 

 but was unable to separate a pleuropneumonia-hke strain from the bacillary organisms. 

 Pleuropneumonia-like Strains in Man. 



Dienes and Edsall (1937) isolated a strain from a suppurating Bartholin's gland in 

 a woman who was working in the laboratory with rats. Subsequently Dienes (1940) 

 demonstrated pleuropneumonia-like strains in the cervical secretion of five patients 

 suffering from pelvic infections. Whether these organisms are pathogenic or not is still 

 undetermined. The frequent association of pleuropneumonia-like organisms with arthritis 

 in rats and mice has naturally raised hopes that they may be responsible for human 

 rheumatism. In spite, however, of prehminary suggestive findings by Swift and Brown 

 (1939), practically all attempts to demonstrate such a relationship have proved unsuccessful 

 (see Sabm 1941). 

 Saprophytic Pleuropneumonia-like Strains. 



Laidlaw and Elford (1936) described the isolation of three pleuropneumonia-like 

 strains, A, B and C, from London sewage by the inoculation of suitable filtrates into 

 FUdes' broth. The organisms grew best at 30° C. in Hartley's horse digest broth, pH 8-0, 

 to which Fildes' peptic digest of red cells had been added. They fermented no sugars 



