FAMILY IV. ENTEROBACTERIACEAE 



337 



Catalase-positive . 



Aerobic, facultatively anaerobic. 



Heat resistance: Usually destroyed in 30 

 minutes at 60° C, but certain heat-resistant 

 strains may withstand this exposure (Ayers 

 and Johnson, Jour. Agr. Res., 3, 1914, 401; 

 Stark and Patterson, Jour. Dairy Sci., 19, 

 1936, 495). 



Growth requirements: Good growth on 

 ordinary laboratory media. Optimum 

 growth temperature, between 30° and 37° C. 

 Growth takes place at 10° and 45° C. Gas 

 produced from glucose at 45° to 46° C. 

 Eijkmann test positive (Eijkmann, Cent. f. 

 Bakt., I Abt., Orig., S7, 1904, 74; Perry and 

 Hajna, Jour. Pact., 26, 1933, 419). 



Serology: A large number of serological 

 types which seem to differ in pathogenic 

 significance are included in this species as 

 defined here. While it has long been known 

 that E. coli is serologically heterogeneous, 

 Kauffmann and his associates have brought 

 some semblance of order to the mass of 

 divergent types present in this species. 

 Among significant contributions to the 

 establishment of a scheme of serological 

 classification, the following may be listed: 

 Kauffmann (Acta. Path, et Microbiol. 

 Scand., 20, 1942, 21; 21, 1944, 20; Jour. 

 Immunol., 57, 1947, 71), Knipschildt (Un- 

 dersogelser over Coligruppens Serologi. 

 A. Busk, Copenhagen, 1945) and Vahlne 

 (Serological typing of the colon bacteria. 

 Gleerupska Univ. Bokhandeln, Lund, 1945). 



Like the salmonellas and shigellas, strains 

 of E. coli are divided into groups on the 

 basis of their heat-stable somatic (O) 

 antigens. The O groups are subdivided on 

 the basis of sheath, envelope or capsular 

 (K) antigens, which have the property of 

 inhibiting O agglutination just as the Vi 

 antigen inhibits the O agglutination of 

 Salmonella typhosa. The ability of these K 

 antigens to inhibit O agglutination is an- 

 nulled by heating, and they are divided into 

 three categories (L, B, A) by their physical 

 properties, particularly by the resistance 

 to heat of their ability to inhibit O aggluti- 

 nation and to bind their respective agglu- 

 tinins. Finally, the organisms are divided 

 into serotypes on the basis of their flagellar 

 (H) antigens. To date, approximately 135 

 O groups, 75 K antigens and 40 H antigens 



have been recognized and characterized. 

 Since these antigens may occur in different 

 combinations, it is obvious that the number 

 of serotj'pes existent within the species is 

 much greater than the number recognized to 

 date. 



Within recent years there has been a great 

 increase in interest in the serology of E. 

 coli due to ihe association of certain sero- 

 types with severe outbreaks of infantile 

 diarrhea. Among the earlier papers dealing 

 with this problem are those of Bray (Jour. 

 Path, and Pact., 57, 1945, 239), Bray and 

 Beaven (Jour. Path, and Pact., 60, 1946, 

 395), Giles, Sangster and Smith (Arch. Dis. 

 Childhood, 24, 1949, 45) and Kauffmann and 

 Dupont (Acta Path, et Microbiol. Scand., 

 27, 1950, 552). Since these papers were 

 published, the observations of the above- 

 mentioned investigators have been con- 

 firmed by a great number of workers in 

 many different countries. While it is not 

 yet clear how many different strains of 

 E. coli may be involved in the etiology of 

 infantile diarrhea, the following have been 

 found repeatedly in association with the 

 disease: 026:P6; 055: B5; 0111 :B4; 0127:B8; 

 and 0128:B12. 



For a comprehensive summary of the 

 association of E. coli serotypes with in- 

 fantile diarrhea and other pathological 

 conditions, see Kauffmann {Enterobac- 

 teriaceae, 2nd edition, E. Munksgaard, 

 Copenhagen, 1954). 



Comments : Many varieties of this species 

 have been given specific or varietal names. 

 The majorit.y of these varieties, a number of 

 which are based on differences in sugar 

 fermentations, are not now regarded as 

 significant. Other varieties have been 

 established on the basis of the production of 

 a yellow pigment, a lack of motility, differ- 

 ences in the appearance of colonial growth, 

 a failure to coagulate milk, an inability to 

 produce indole or on the basis of isolation 

 from different regions of the intestine or 

 other differences in habitat, etc. 



Source: Originally isolated by Escherich 

 from the feces of breast-fed infants. 



Habitat: Found as a normal inhabitant 

 of the intestines of mail and of other 

 vertebrates. Widely distributed in nature. 

 Frequently causes infections of the urogeni- 



