PROTEUS MORQANl 651 



and then digest it ; others digest it without preliminary coagulation ; the litmus 

 is reduced. Indole is produced by the maltose-fermenting, but not by the 

 maltose- negative strains. H gS -| — \-. NH 3 -| — |- . Catalase -| — \- . Methylene blue 

 reduction -f . Nitrates reduced to nitrites. M.R. . ±. V.P. -)-, if Barritt's method 

 is used. Urea is decomposed with the formation of NH3. 



Antigenic Structure. — Incompletely worked out. By direct agglutination the swarming 

 strains can be divided into 3 main groups, but several smaller groups are present ; 

 by absorption the main groups can be divided into sub-groups. No apparent 

 relationship between the serological and the biochemical grouping. The O antigens 

 tend to be ty^jc-specific. Among the X strains the OX 2, OX 19, and OX K strains 

 are distinct. 



Pathogenicity. — Produces no specific infection under natural conditions, but is frequently 

 found in cystitis, infantile diarrhtea, and suppurative lesions generally. Is pro- 

 bably responsible for one form of calf dysentery. Virulence to laboratory animals 

 is variable. Highly virulent cultures inoculated intraperitoneally into rabbits, 

 rats, or guinea-pigs cause death in a few hours, presumably from toxaemia. Less 

 virulent cultures cause emaciation with death in a week or more after intraperitoneal 

 inoculation, and abscesses and inflammatory conditions lasting for months after 

 subcutaneous inoculation. In fatal cases the organisms can generally be recovered 

 from the blood and viscera. 



Proteus morgani was isolated by Morgan (1906) from the stools of patients with 

 Bummer diarrhoea. It is motile by 25-30 peritrichate flagella. Motility is 

 sometimes lost after long cultivation, but it may sometimes be restored by 

 passage through broth at 20° C. Though not swarming at 37° C. on ordinary agar, 

 it swarms readily at 20-28° C. on 1 per cent. agar. Variant types, however, occur 

 which are less actively motile, and which give rise to characteristic streaming 

 colonies. The general cultural characters resemble those of the coliform group. 

 Acid and a small amount of gas are produced in glucose peptone water within 24 

 hours. Xylose is often fermented with the production of acid only, while occasional 

 strains are said to produce acid and a small amount of gas in sucrose after 10 days. 

 Gelatin is not liquefied, but both indole and HjS are formed abundantly. Litmus 

 milk is turned alkaline. About 30 per cent, of strains give rise to a heemolysin for 

 sheep red cells. Antigenically, most workers (Lewis 1911-12, Kligler 1919, Thojtta 

 1920, Jordan, Crawford, and McBroom 1935), including ourselves, have noted the 

 extraordinary heterogeneity of members of this species. Rauss (1936), who has 

 made a careful study of this question, finds that the H antigen tends to be group- 

 specific and the antigen type-specific. Seven H receptors and 17 receptors were 

 differentiated in 48 strains. One of the H antigens in P. morgani is similar to one 

 of the H antigens in P. vulgaris. The organism seems to be mainly parasitic and 

 potentially pathogenic, assuming a considerable role in some outbreaks of infantile 

 diarrhoea. It has been isolated from paratyphoid-like fevers (Havens and Mayfield 

 1930). Infections in birds, mammals, and reptiles are not uncommon (Lovell 1929), 

 while in mice it may give rise to spontaneous epidemics of enteritis (Wilson 1927), 

 especially in the late summer and autumn months. Experimentally, it produces a 

 rapidly fatal infection in mice on intraperitoneal inoculation. It does not produce 

 a soluble toxin. 



Other types of bacilli were isolated by Morgan (1906, 1907), which are sometimes 

 called after him, and which differ from his No. 1 bacillus in their motility, their 

 action on milk, or some other characteristic ; but the term Morgan's bacillus is 

 generally used to indicate the organism we have just described. 



