BACILLUS PYOCYANEUS 579 



ment which is fluorescent and insoluble in chloroform, but soluble in 

 water/ This pigment is common to other fluorescent bacteria, and not 

 peculiar to Bacillus pyocyaneus. The reddish-brown color seen in old 

 cultures ^ and supposed by some writers to be a third pigment, is probably 

 a derivative from pyocyanin by chemical change. 



Chloroform extraction of pyocyanin from cultures may serve oc- 

 casionally to distinguish the pyocyaneus bacilli from other similar 

 fluorescent bacteria. Ernst has claimed that there are two types of B. 

 pyocyaneus, an a-type which produces only the fluorescent, water- 

 soluble pigment, and a /J-type which produces both this and pyocyanin.^ 



Pathogenicity. — Bacillus pyocyaneus is one of the less virulent patho- 

 genic bacteria. It is widely distributed in nature and may be found 

 frequently as a harmless parasite upon the skin or in the upper respira- 

 tory tracts of animals and men. It has, however, occasionally been 

 found in connection with suppurative lesions of various parts of 

 the body, often as a mere secondary invader in the wake of another 

 incitant, or even as the primary cause of the inflammation. In most 

 cases where true pyocyaneus infection has taken place, the subject is 

 usually one whose general condition and resistance are abnormaUy low.* 

 Thus pyocyaneus may be the cause of chronic otitis media in Hi-nour- 

 ished children. It has been cultivated out of the stools of children suf- 

 fering from diarrhea, and has been found at autopsy generally distributed 

 throughout the organs of children dead of gastro-enteritis.' It has been 

 cultivated from the spleen at autopsy from a case of general sepsis 

 following mastoid operation. The bacillus has been found, further- 

 more, during life in pericardial exudate and in pus from liver abscesses." 



Brill and Libman,' as weU as Finkelstein,' have cultivated 

 B. pyocyaneus from the blood of patients suffering from general sepsis. 

 Wassermann ° showed the bacillus to have been the etiological factor in 

 an epidemic of umbilical infections in new-born children. Similar exam- 

 ples of B. pyocyaneus infection in human beings might be enumerated in 

 large numbers, and there is no good reason to doubt that, under given 



* Boland, loc. cit. 



' Gessard, Ann. de I'inst. Pasteur, 1890, 1891, and 1892. 



» Ernst, Zeit. f. Hyg., ii, 1887. 



« Rohner, Cent. f. Bakt., xi, 1892. 



'^ Neumann, Jahrb. f. Kinderheilk. , 1890. 



' Kraunhals, Zeit. f. Chir., xxxvii, 1893. 



' Brill and Libman, Amer. Jour. Med. Sci., 1899. 



* Finkelstein, Cent. f. Bakt., 1899. 



• Wassermann, Vij'cbow's Alpb., clxv, 1901- 



