THE EL TOR STRAIN 365 



tion in a lower dilution cannot be accepted as evidence of a Flexner infection 

 because, as has already been pointed out, normal serum in low dilution often 

 has an agglutinating action on this type of the bacillus. 



In dysentery, as in enteric fever, a positive reaction confirms the diagnosis : 

 on the other hand if no reaction be obtained bacillary dysentery cannot be 

 definitely excluded, because the blood may have been collected before 

 agglutinins had developed. 



[Bacillus dysentericus El Tor No. I. 1 ] 



This organism which was described by Armand Ruffer in 1909, was found to 

 be the cause of the largest percentage of the cases of dysentery among the Mussulman 

 pilgrims passing through the lazaret at El Tor : it has the characteristics of the 

 dysentery group, but appears to differ from all the known sub-groups at present 

 described. Ruffer, however, remarks that the name is merely provisional and that 

 the bacillus may prove to be identical with one of the bacilli already described. 



Morphology. The bacillus Tor No. 1 is similar to, but plumper than, the Shiga 

 bacillus ; filaments were rarely seen ; no spores were found nor could cilia be 

 demonstrated. It showed movement of spiral rotation when freshly isolated but 

 no movement of progression : in sub-cultures it was quite motionless. 



Cultures. Broth. Uniform turbidity : no pellicle. 



Gelatin. Not liquefied. The colonies have no vine-leaf appearance like those of 

 the Shiga bacillus. 



Agar. Similar to typhoid. 



On Endo's medium. Colourless. 



On Conradi-Drigalski's agar. Like typhoid. 



Bio-chemical reactions. B. dysentericus Tor No. 1 formed acid out of mannite 

 and thus resembled Flexner' s bacillus. In saccharose, maltose, salicin, sorbite, 

 dulcite and dextrin reactions were very inconstant and differed with different strains 

 of the bacillus. 



A small amount of indol was formed sometimes but the reaction was not constant. 



In milk, no clot was formed. 



In litmus milk most strains produced first an acid reaction followed by a stage of 

 increased alkalinity. One of the strains however produced a permanent acidity. 



Pathogenicity. The B. dysentericus Tor No. 1 was highly pathogenic to rabbits 

 on intra-peritoneal or intra- venous inoculation, giving rise to fever, diarrhoea and 

 paralysis and causing death in 24 hours to 5 days according to the dose inoculated. 

 The pathogenicity for rabbits rapidly disappeared in sub-cultures. 



Guinea-pigs were even more susceptible than rabbits. The symptoms and lesions 

 were the same as in the rabbit. 



In horses inoculation of sterilized cultures produced a wide-spread oedema about 

 the site of inoculation, rise of temperature and a general condition of ill-health. 



In man the clinical signs and pathological appearances were indistinguishable 

 from those produced by infection with the Shiga bacillus. 



Toxin. None of the cultures of this organism gave a soluble toxin. 



Agglutination. The serum of patients suffering from a Tor No. 1 infection did 

 not agglutinate the Shiga bacillus but agglutinated bacillus Tor No. 1 constantly 

 except in early acute cases or in very feeble old people. The dilution in which 

 agglutination could be obtained varied from 1 in 25 to 1 in 300, the index rising 

 during convalescence. 



With the serum of animals specifically immunized it was found that the Tor 

 bacillus was agglutinated in dilutions of 1-1000 to 1-2000 with a Tor serum, while 

 with a Shiga serum agglutination was inconstant in a dilution of 1-100, and with 

 a Flexner serum agglutination was effected with a dilution of 1200 but not with a 

 dilution of 1-500. 



Serum therapy. Ruffer found that patients suffering from a Tor infection were 

 not benefited by treatment with a Shiga serum while severe cases were quickly 

 cured by inoculation with the serum of an horse immunized with B. dysentericus 

 Tor No. 1. 



[ ir This section has been added.] 



