Pseudomonas Aeruginosa

PSEUDOMONAS AERUGINOSA (Bacillus pyocyaneus Gessard, Bacterium pyocyaneum Lehmann u. Neumann, Pseudomonas aeruginosa Migula, Bact. aeruginosum Schroter) is the causative agent of suppuration and imparts to pus its peculiar green or blue-green color; this coloration depends on the pigment produced by B. pyocyaneus. In a pure culture, B. pyocyaneus was obtained in 1882 by Gessard. Subsequently, by the work of Schimmelbusch, Charren, and Kossel, it was established that B. pyocyaneus plays a certain role in human pathology, being sometimes the causative agent not only of local processes (otitis, angina, furuncles) but also of septic diseases (see Sepsis). B. pyocyaneus was most often found in lesions of the gastrointestinal tract, especially in children. Cases of diseases of the respiratory tract (lung gangrene) and urinary apparatus caused by B. pyocyaneus have also been described. In exhausting diseases (typhoid fever, chronic dysentery), B. pyocyaneus, penetrating into the blood and organs, can be the cause of secondary infections. B. pyocyaneus is also encountered in the human organism as a saprophyte; it is often found on the surface of the skin and in the contents of the intestine. In the external environment, B. pyocyaneus has been repeatedly isolated from water, soil, and dust (Bonjean). Monotrichous, motile, short, polymorphic bacilli with rounded ends, 1.5x0.5-0.6 µm. Grows at a temperature of 15-45°C. The optimum temperature for growth is 37°C. More luxuriant growth is obtained in the presence of O₂, but it can also grow under anaerobic conditions. It grows well on ordinary nutrient media and on media with a low content of nutrients. Cultures possess an aromatic odor reminiscent of the smell of flowering linden. It does not decompose sugars, does not form indole, and possesses sharp proteolytic and hemolytic properties. It forms the following pigments: 1) pyocyanin — blue, soluble in water, chloroform, and diluted alcohol; 2) green fluorescent pigment, common to all fluorescent bacteria; 3) green non-fluorescent; 4) red-brown; and 5) brown-black. Gessard succeeded in obtaining variants on artificial media that form only a single pigment, for example only blue pyocyanin or only the green fluorescent pigment. The microbe contains the following enzymes: protease, which liquefies gelatin and dissolves other proteins (fibrin, casein, coagulated serum, egg white); oxidase; and reductase. The proteolytic enzyme of Pseudomonas aeruginosa, called pyocyanase, owing to its ability to dissolve many species of microbes in a living state, was applied for therapeutic purposes (see Pyocyanase). According to recent data, the hemolytic properties of Pseudomonas aeruginosa depend not on alkali formation, as the old authors thought, but on the presence of a thermostable hemolysin of lipoid nature. Pseudomonas aeruginosa is pathogenic for animals, and the guinea pig is the most sensitive. Rats, white mice, and rabbits are somewhat less sensitive, but they die in the same way as guinea pigs in the presence of signs of intoxication. The question of whether Pseudomonas aeruginosa excretes exo- or endotoxin remains disputed. Upon immunization of animals, a very weak antitoxin is formed, and neutralization of the toxin by antitoxin does not follow the law of multiple proportions, which, in the opinion of some, speaks for the formation of Pseudomonas aeruginosa not of a true EXOTOXIN but of an ENDOXOTOXIN.

E. Bunina. Infection by Pseudomonas aeruginosa easily affects purulent, heavily contaminated wounds. This is observed especially frequently after gunshot wounds with extensive tissue destruction and in cases of prolonged suppuration. During the recent wars, it was necessary to observe entire epidemics caused by Pseudomonas aeruginosa in hospitals. It is characteristic that wounds that were already suppurating before the addition of this new infection begin to secrete much more strongly, soaking dressings with a huge amount of green pus with a characteristic sweetish odor. The process of healing is very strongly delayed in this case, granulations become flaccid and pale. The skin around the wound is covered with a green coating, which is difficult to wash off with gasoline. A number of means have been proposed for the fight against wound infection by Pseudomonas aeruginosa, with which the wound and surrounding skin are smeared. Gasoline, iodine, Burov's fluid are recommended, and especially 3% hydrogen peroxide in the form of moist dressings. Unfortunately, often all these means prove to be of little effect.