I 



CHAPTER XXV. 



THE PAEATYPHOID BACILLI. 1 

 (THE PARACOLON BACILLI.) 



The origin of the terms paratyphoid and paracolon, p. 420. The relation of the 

 " paratyphoid " bacilli to the " hsemorrhagic septicaemia " group of organisms and to 

 the " enteritidis " group, p. 421. 



The origin and definition of the " Salmonella group," p. 422. 



Other names suggested for the " paratyphoid group," p. 422. 



The classification adopted in the following pages, p. 422. 



UNDER the heading of paratyphoid bacilli are described certain organisms 

 which in many respects resemble the typhoid and the colon bacilli : they 

 are all gram-negative motile bacilli which do not form spores and do not 

 liquefy gelatin. From the clinical standpoint also, though the symptoms 

 are markedly different, there is a certain resemblance in that the diseases 

 produced by the typhoid and paratyphoid bacilli and probably also by 

 the colon bacillus are all primarily of a septicsemic nature. 



The name paratyphoid was introduced by Achard and Bensaude in 1896 

 to describe an organism (paratyphoid B) 2 resembling the typhoid bacillus, 

 which they had isolated from a case of osteomyelitis following an attack of 

 a disease clinically indistinguishable from enteric fever, and from the urine 

 of another case of a similar disease. 



In 1897 Besson isolated a similar organism from a case of pericarditis follow- 

 ing a disease which had been diagnosed as enteric fever. 



In 1897 Widal and Nobecourt also found a similar organism (paratyphoid 

 B) 2 in pus from a thyroid abscess in which there were no symptoms of a general 

 infection. To this organism they gave the name " para-colon " bacillus. 



Gwyn in 1898 was the first to isolate a " para-colon " bacillus from the 

 blood of a person suffering fro,m a disease clinically indistinguishable from 

 enteric fever. 



In 1900-1 Schottmuller undertook an investigation into the nature of the 

 organisms present in the blood of cases which had the clinical symptoms of 

 enteric fever. In addition to the typhoid bacillus he found two other species 

 of organisms, closely related to the typhoid bacillus and to each other, to 

 which Brion and Kayser gave the names paratyphoid A and paratyphoid B ; 

 the latter being the more frequently found. To these organisms then the 

 term " paratyphoid " is properly applied : organisms, that is, which have many 



1 This part of the subject has been entirely rewritten. 



2 See Boycott, Journal of Hygiene, vi. 33 et seq. 



