BACILLUS PROTEUS 455 



On agar and other solid media, as well as upon gelatin before lique- 

 faction has taken place, characteristic colonies are produced. From 

 the central flat, grayish-white colony nucleus, numerous irregular 

 streamers grow out over the surrounding media, giving the colony a 

 stellate appearance. On potato, it forms a dirty, yellowish growth. 

 In milk f there is coagulation and an acid reaction at first; later the 

 casein is redissolved by proteolysis. Blood serum is often liquefied, 

 but not by all races. 



A great many really dissimilar bacteria have been described under 

 the name of Proteus. The type of the group is the so-called Proteus 

 vulgaris (Hauser, 1885). Other organisms spoken of as proteus are 

 the Proteus mirabilis, which differs in slower gelatin liquefication 

 from vulgaris, the Proteus Zenkeri, which does not liquefy gelatin, 

 the Proteus septicus, and the Bacillus Zopfi, a Gram-positive organ- 

 ism. A good many of these were formerly classified as of Bacterium 

 termo. Closely related is the slow liquefying organism known as 

 Bacillus cloacce, common in sewage. 



There is no group which so urgently requires study as this, since 

 organisms belonging here are so often found in the human body and 

 human excreta. In urine we have encountered a non-gelatin liquefy- 

 ing Gram-negative bacillus belonging to this group which has given 

 us much trouble in identification. As far as we can establish any 

 general characteristics for the group at all, we may say that they are 

 Gram-negative, non-spore-bearing, motile bacilli, which on the surface 

 of gelatin plates show colonies characterized by spreading streamers, 

 most of which liquefy gelatin, a few of which, however, do not. All 

 of them ferment dextrose and saccharose with gas, but do not attack 

 lactose. 



The pathogenic powers of proteus are slight. Large doses injected 

 into animals may give rise to localized abscesses. In man proteus in- 

 fections have been described in the bladder, in most cases, however, 

 together with some other microorganism. The Urobacillus lique- 

 faciens septicus described by Krogius was a variety of this group. 

 Epidemics 1 of meat poisoning have been attributed to the proteus 

 family by some observers. Thus Wesenberg 2 cultivated a proteus 

 from putrid meat which had caused acute gastroenteritis in sixty- 

 three individuals. Similar epidemics have been reported by Silber- 

 schmidt, 3 Pfuhl, 4 and others. 



1 Schnitzler, Cent, f . Bakt., viii, 1890. 2 Wesenberg, Zeit. f. Hyg., xxviii, 1898, 



3 Silberschmidt, Zeit. f . Hyg., xxx, 1899. _ 4 Pfuhl, Zeit. f, Hyg., xxxv, 1900. 



