THE INFECTIOUS DISEASES. 211 



once it gains access to the tissues of the body, especially if these be 

 otherwise injured beforehand. Local infection with this organism is 

 often associated with serious toxaemia and septicaemia. Intravascular 

 injections of virulent cultures in rabbits are usually followed by symp- 

 toms and lesions of septicaemia. Introduced subcutaueously and intca- 

 peritoneally, it may excite local suppuration or sero-fibriuous inflamma- 

 tion, often haemorrhagic in character, terminating fatally. 1 



There are so many organisms so closely resembling the colon bacillus 

 in their morphological and biological characters that it has been found 

 convenient to consider them as possible variations of one form and to 

 speak of them collectively as the "colon group." The differentiation 

 between the individual members of this group and between these and the 

 typhoid bacillus has presented many difficulties to bacteriologists and 

 given rise to much technical finesse. It is now possible to differentiate 

 between the members of the colon group and the typhoid bacillus and 

 to separate them in pure cultures (see p. 237). 



THE BACILLUS PYOCYANEUS. 



This has been known for several years as an organism occasionally 

 found in pus to which in its growth it imparted a greenish color. 

 Charriu in 1889 established the significance of the organism as an exci- 

 tant of suppurative inflammation and various manifestations of septi- 

 caemia to which he gave the name " Maladie pyocyanique. " Since this time 

 many cases have been reported in which the Bacillus pyocyaneus, either 

 alone or in association with other organisms, has been found ; for ex- 

 ample, in purulent otitis media, angina, endocarditis and pericarditis, 

 suppurative inflammation of the urinary tract, meningitis, broncho-pneu- 

 monia, gastro-iutestiual disturbances in infants and adults, and in lesions 

 of the skin as well as in systemic infections arising from primary local 

 suppurative inflammation. The green color is not always present in the 

 lesions, being first developed in the cultures or in experimental animals. 



The occurrence of the organism is on the whole infrequent. It was 

 found by Jadowski twice in systematic cultures of the exudate from two 

 hundred cases of suppurating wounds. Barker found it in eleven out of 

 eight hundred cases in which systematic cultures from autopsies were 

 made. It was found in three out of one hundred cases examined by 

 Lartigau. Among the more marked lesions which may be present in 

 cases of pyocyaneus infection, we may mention albuminous degeneration 

 in the viscera, focal necroses, haemorrhages, local hyperplasire v Oertel's 

 lesion) in the lymph-nodes and nodules throughout the body, and espe- 

 cially superficial, circumscribed or diffuse necrosis and ulceratiou in the 

 intestinal mucous membrane. 2 



1 For details concerning B. coli, with bibliography, see Lartiga^l, "Studies from the 

 Dept. of Path., Col. of Pliys. and Surg., Columbia University, vol. viii., 1902; also con- 

 sult Mace, "Traitede Bacteriologie," 1901; also Eaclie.nch and Pfaundler in Kolle and 

 Wassermann's "Handbuch der Mikroorganismen," Bd. ii., p. 334. 



'-For a critical summary of the cases with original studies and bibliography consult 

 Lartigau, Philadelphia Medical Journal, September 17tb, 1898; also Journal of Experi 

 mental Medicine, vol. iii., p. 595, 1898. 



