BACILLUS PROTEUS GROUP ;^97 
of this illness, particularly those characterized by choleraic symptoms. 
Frost' has isolated a proteiis bacillus from water which is agglutinated 
in higher dilution with a typhoid serum than the typhoid bacillus 
itself. This organism, however, does not stimulate the formation of 
typhoid agglutinins in experimental animals. Certain strains of 
proteus bacilli (X2 and X19) are of great value in the diagnosis of 
typhus fever (see Typhus, Chapter XXVIII for details), but so far as 
can be determined they have no etiological relationship to the disease. 
Bacillus proteus is not very pathogenic for laboratory animals. 
The injection of large doses usually causes death. 
Bacteriological Diagnosis.— B. proteus is readily isolated upon 
gelatin plates; the bacilli grow rapidly at room temperature and 
liquefy the medium around each individual colony. Subcultures in 
sugar media, gelatin and milk produce the changes outlined above. 
B. proteus may be confused with B. cloacae, because the latter organ- 
ism ferments lactose more slowly than other sugars.- B. cloacae, how- 
ever, is distinctly less proteolytic than B. proteus^ and it produces 
less acid and more gas from glucose* 
1 Bull. No. 66, 1910, U. 8. Pub. Health and Marine Hosp. Service. 
2 Theobald Smith: Fermentation Tube, 1893, p. 215. 
3 Kendall, Day and Walker: Loc. cit., p. 1230. 
* For Felix- Weil reaction with Bacillus proteus in typhus fever see page 644. 
