230 BACTERIOLOGY FOR NURSES 



Pathogenesis. B. pyocyaneus has been found in water, in 

 the feces of many animals, and on the skin of healthy human 

 beings, and for some time after its isolation it was regarded as a 

 harmless saprophyte or at most of very limited pathogenic power. 

 Later evidence has proved that not only does its presence in 

 mixed infections retard the process of repair, but it has the power 

 of producing suppuration itself. It has been found in pure cul- 

 tures in cases of ophthalmia, broncho-pneumonia, and otitis media. 

 Thus while only slightly pathogenic it may in cases of lowered 

 vitality produce a serious infection. 



BACILLUS PROTEUS 



B. proteus, or rather the group of organisms known by that 

 name, is abundantly found in soil and water and almost wherever 

 putrefactive changes in organic matter are occurring. The or- 

 ganisms were discovered by Hauser in 1885. The number of va- 

 rieties contained in the group has not been clearly defined. The 

 following description, however, may be considered as typical. 



Morphology and Staining. The average length is about 1.2 

 p and the width about 0.6 p. The organism does not form 

 spores. It possesses many peritrichal flagella, is actively motile, 

 stains readily with the anilin dyes, and is Gram negative. 



Cultivation. An aerobe and facultative anaerobe, it grows well 

 on the ordinary culture media. Gelatin liquefaction commences 

 at the end of ten or twelve hours. On agar slants a spreading, 

 white, moist growth appears and on agar plates colonies tend to 

 become confluent. Dextrose and saccharose are fermented with 

 the production of acid and gas. In peptone solution indol and 

 phenol are produced. In urine the organisms decompose urea 

 into ammonium carbonate. 



Pathogenesis. Cultures injected subcutaneously into guinea 

 pigs or rabbits cause purulent abscesses or death with symptoms 

 of poisoning. 



In man B. proteus has been found in a variety of pathological 

 conditions: in purulent peritonitis, cystitis, and pyelonephritis. 



