Bacillus Coli Communis, Escherich (1885). 



bacteeidm coli commune; the colon bacillus; emmerich's 

 bacillus; b. neapolitanus. 



Origin.— It is very common and constant in the intestinal con- 

 tents of man and animals, especially in the colon; occurs in the dis- 

 charges of healthy infants, also in summer diarrhea. It is frequently 

 present, accompanying the comma bacillus, in the discharges of 

 Asiatic cholera, and in later stages may be the only organism pres- 

 ent. Not infrequently it is present in pus (B. pyogenes fcetidus). It 

 is apparently the most frequent cause of appendicitis. In many 

 respects it resembles the typhoid fever bacillus. 



Form.— Short, narrow rods; may vary in length from oval or 

 coccus-like forms to rods 4-6 times as long as wide. Usually grows in 

 pairs; occasionally in short threads. 



Motility.— Exceedingly variable, depending upon the tempera- 

 ture, age and the medium. Diffuse flagella and giant-whips present. 



Sporulation. — Not observed. 



Anilin dyes.— It stains readily, but not by Gram's method. Bi- 

 polar stain frequently met with; likewise plasmolytic changes, as in 

 potato cultures. 



Growth. — Is more rapid than that of the typhoid bacillus. 



Plates. — On gelatin plates the surface colonies are flat, spreading, aniso-diametric, 

 and have a dull-white color. The border is irregular and markings are present in the outer 

 zone. The deep colonies are yellowish, round or oval; frequently divided, forming loliu- 

 lated masses. The deep circular colonies usually show a yellow granular center which is 

 surrounded by a colorless, homogeneous ring (dish appearance) . No liquefaction. Strong 

 amine and indol order. Moreover, the gelatin owing to the ammoniacal reaction, deposits 

 a cloudyprecipitate between the colonies, and along any scratches that may be on the glass- 

 plate. These characteristics are not given by the typhoid bacillus. 



Stab culture. — Rather energetic growth along the line of inoculation, while on the sur- 

 face it spreads as a white film witn wavy border. 



Streak culture. — On agar^ it forms a moist, white, spreading growth; old cultures 

 may show needle-shaped crystals. On potato, it forms an abundant, yellowish, moist, 

 slowly spreading growth. 



Milk. — Is coagulated in one or two days, though at times a week or more may be 

 necessary. 



Uschinsky^s fluid gives a good growth; likewise a solution of ammonium chloride and 

 . glycerin — distinction from the typhoid bacillus. 



Bouillon becomes very clouded. The sediment is heavy and a thick ring may adhere 

 to the glass at the surface of the liquid. At times a broken pellicle may form. Indol reac- 

 tion is marked. 



Hiss^ and Sioddart's media yield diffuse growths according to the motility of the 

 species. 



Oxygen requirements. — Is a facultative anaerobe. 



Temperature. — Grows well at ordinary temperature. Its opti- 

 mum is about 37". 



Behavior to gelatin. — Does not liquefy. 



Aerogenesis. — Carbonic acid and hydrogen is produced in abund- 

 ance when glucose is present. Unlike the typhoid bacillus it can 

 form acid and gas in lactose media. 



Pathogenesis. — Guinea-pigs are very susceptible; rabbits less so; 

 mice insusceptible. Small quantities injected intravenously or into 

 the abdominal cavity produce diarrhea, collapse and death in 1-3 

 days. The small Intestine is hyperemic, more or less intensely in- 

 flamed; serous exudates may be present. The bacilli are abundant in 

 the blood and organs and on the peritoneum. Subcutaneous injection 

 is usually non-fatal and produces only a local abscess. 



Diagnosis.— See p. 364. 



352 



