CHAPTER XLI 

 BACILLUS PYOCYANEUS 



IT is a matter of common surgical experience that many suppurating 

 wounds, especially sinuses of long standing, discharge pus which is of a 

 bright green color. The fact that this peculiar type of purulent inflam- 

 mation is due to a specific chromogenic microorganism was first demon- 

 strated by Gessard l in 1882. The bacillus which was described by Ges- 

 sard has since become the subject of much careful research and has been 

 shown to hold a not unimportant place among pathogenic bacteria. 2 



Morphology and Staining. Bacillus pyocyaneus is a short rod, usu- 

 ally straight, occasionally slightly curved, measuring, according to 

 Fliigge, about 1 to 2 micra in length by about 0.3 of a micron in thickness. 

 The bacilli are thus small and slender, but are subject to considerable 

 variation from the measurements given, even in one and the same cul- 

 ture. While ordinarily single, the bacilli may be arranged end to end in 

 short chains of two and three. Longer chains may exceptionally be 

 formed upon media which are especially unfavorable for its growth, such 

 as very acid media or those containing antiseptics. 



Spores are not found. The bacilli are actively motile and possess 

 each a single flagellum placed at one end. 



Bacillus pyocyaneus is stained easily with all the usual dyes; but is 

 decolorized by Gram's method, Irregular staining of the bacillary body 

 is common, but is always an indication of degeneration, and not a 

 normal characteristic, as, for instance, in the diphtheria group. 



Cultivation. The pyocyaneus bacillus is aerobic and facultatively 

 anaerobic. It can be adapted to absolutely anaerobic environments, but 

 does not produce its characteristic pigment without the free access of 

 oxygen. The bacillus grows readily upon the usual laboratory media 

 and is not very sensitive to reaction, growing equally well upon moder- 

 ately alkaline or acid media. Development takes place at temperatures 

 as low as 18 to 20 C., more rapidly and luxuriantly at 37.5 C. 



* i Gessard, These de Paris, 1882. 

 2 Charrin, " La raaladie pyocyanique/' Paris, 1889, 

 577 



