508 PSEUDOMONAS 



are non-pathogenic to man. Ps. pyocyanea itself gives rise occasionally to suppura- 

 tive processes and less often to generalized infection. Among the commonest 

 manifestations are middle-ear suppuration in children, destructive lesions of the 

 skin, sometimes described as ecthyma gangrenosum, in children and adults, and 

 necrotic and ulcerative lesions of the alimentary mucosa. The respiratory tract, 

 the eye, the joints, and the kidneys are sometimes affected. Wounds are often 

 infected. There is also reason to believe that the organism plays a part in some 

 cases of infantile diarrhoea. Infection may be primary or secondary, and is often 

 acute and rapidly fatal. (For review of human infections see Waite 1908, Fraenkel 

 1917, and Lode 1929.) 



Animals are rarely infected unless given large doses intravenously, when they 

 may die of intoxication. Ps. pyocyanea, however, often produces fever and a local 

 abscess after subcutaneous injection into rabbits ; and, if highly virulent, it may 

 prove fatal in 24 hours. 



Group forming Bluish-green Pigment. — Ps. pyocyanea, first isolated in pure 

 culture by Gessard (1882), is widely distributed in nature, being found in water, 

 sewage, and sometimes on the normal skin, particularly of the axilla and 

 perineum (Ruzicka 1898). It is not infrequently found in wounds, where it 

 gives rise to blue pus. It may invade the nasal fossse, the middle ear, the 

 meninges, the bronchi and other organs, and set up suppuration. In infants 

 and young children it causes intestinal disturbances and diarrhoea ; sometimes 

 it enters the blood stream, and gives rise to a general infection (Williams and 

 Cameron 1896). According to Pons (1927), Ps. pyocyanea is especially pathogenic 

 in the tropics, where it is not infrequently responsible for typhoid-like infections 

 and abscess of the liver. 



Injected subcutaneously or intravenously into guinea-pigs or rabbits in a dose 

 of 0-5-10 ml. of a 24 hours' broth culture, it may cause death in 24 to 48 hours ; 

 post mortem there is a haemorrhagic oedema at the site of injection (after sub- 

 cutaneous inoculation), small punctate haemorrhages are seen in the stomach and 

 intestine, and sometimes nephritis. The bacilli can be recovered from the blood, 

 viscera, and urine. As much the same appearances result from the injection of 

 dead cultures, it is probable that an endotoxin is responsible. Different strains 

 vary in virulence ; some do not kill for weeks, others not at all. 



Little is known of the antigenic structure of this organism. Boivin and Mesro- 

 beanu (1937), using their trichloracetic acid technique, isolated a glyco-lipoid 

 complex or endotoxin containing a polysaccharide hapten. By inoculation of 

 rabbits with the whole complex they obtained antisera which precipitated the 

 homologous endotoxin and the polysaccharide hapten, and which agglutinated 

 the homologous bacteria. The endotoxin, as a whole, killed mice, but the poly- 

 saccharide hapten was non-toxic on intraperitoneal inoculation, even in doses 

 of 5 mgm. The authors conclude that the identity of the endotoxin with the 

 somatic antigen of Ps. pyocyanea is similar to that in members of the Salmonella 

 group. 



In culture, Ps. pyocyanea forms a bluish-green pigment. Gessard (1890, 1891, 

 1892) found that this pigment consists of two different substances. One, pyocyanin, 

 is bluish-green, non-fluorescent, is formed in peptone media, and is soluble in both 

 chloroform and water. The other, fluorescin, is greenish-yellow, fluorescent, is 

 formed only in the presence of a phosphate, and is insoluble in chloroform, but 

 soluble in water. By cultivation in different media he was able to obtain varieties 



