CHAPTER XXIV 







THE PARATYPHOID AND SIMILAR BACILLI 



There are a number of organisms that produce manifestations of disease sim- 

 ilar to typhoid fever. Some of them closely resemble the typhoid bacillus in 

 morphology, staining and cultural characteristics. Of these the most important 

 are as follows: 



PARATYPHOID A BACILLUS. 

 PARATYPHOID B BACILLUS. 

 BACILLUS ENTERITIDIS OF GAERTNER. 



PARATYPHOID A BACILLUS 



The paratyphoid A bacillus produces a clinical picture indistinguishable 

 from a mild typhoid infection or typhoid fever. 



The distribution of the paratyphoid A bacillus in the human body is similar to 

 that of the typhoid bacillus. The resistance of these two organisms is practi- 

 cally identical. Pollution of soil, water, etc., and the mode of infection very 

 probably is the same in paratyphoid fever as in typhoid fever. 



The morphology, staining, and motility of the paratyphoid A bacillus is 

 indistinguishable from that of the typhoid bacillus. The growth of these two 

 organisms is the same on most culture media. 



Milk is not coagulated but is acidulated in from 24 to 48 hours; the reaction 

 remaining constantly acid thereafter. In media containing glucose acid and gas 

 is formed. There is no gas nor acid production with lactose. 



Toxin. The paratyphoid A bacillus forms an intracellular toxin. 



Agglutinins are found in the serum of patients and inoculated animals under 

 the same conditions as in typhoid infections. Just as typhoid agglutinins are 

 specific for the typhoid bacillus and do not agglutinate paratyphoid bacilli, so, 

 too, paratyphoid A serum is specific for the paratyphoid A bacillus and does not 

 agglutinate the typhoid bacillus. The specificity of, these agglutinations is 

 limited by the occurrence of group-agglutination reactions as will be explained 

 in the chapter on diagnosis. 



PARATYPHOID B BACILLUS 



The paratyphoid B bacillus has the same morphology, staining and resistance 

 and, in many respects, the same cultural characteristics as the typhoid and 

 paratyphoid A bacilli. 



Unlike them, it infects some of the lower animals, mice, swine and cattle, as 

 well as man. It would seem that infections with paratyphoid B bacillus more 

 often result from the consumption of diseased and contaminated foodstuffs, 

 especially meats, than is the case in typhoid and paratyphoid A infections. 



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