144 
PRINCIPLES OF BACTERIOLOGY 
Although the colon bacillus is a normal inhabitant of 
the human intestine and a useful one, too, since its pres¬ 
ence seems to inhibit the growth of many harmful putre¬ 
factive bacteria, yet at times it gives rise to various dis¬ 
eases; as a rule any enfeebled condition seems to make 
it easier for the colon bacillus to become pathogenic; 
among the various diseases caused by this organism are 
the various diarrheas—cholera infantum and cholera nos¬ 
tras, occasionally peritonitis (but usually accompanied by 
other organisms) ; very frequently it is found in inflam¬ 
matory conditions of the liver, gall bladder, and appen¬ 
dix; one of the most frequent conditions caused by the 
colon bacillus is the inflammation of the urinary bladder 
(cystitis) and pyelitis (inflammation of the basin of the 
kidney). 
It is often found in the abscesses within the abdominal 
and pelvic cavities. 
No special precautions are called for in handling the 
colon infections, beyond following the usual hygienic 
and sanitary rules. 
Bacillus coli communior differs from the colon bacillus 
in fermenting and producing gas on saccharose in addi¬ 
tion to all other sugars. 
VI. Mechanism of Infection of Immunity 
The colon bacillus produces an endotoxin, and the anti¬ 
bodies produced by the animal during the colon infec¬ 
tions are the bacteriolysins, precipitins and agglutinins. 
VII. Bacteriologic Diagnosis 
The differentiation of the colon, typhoid, paratyphoid 
and dysentery bacilli will be discussed fully in the chap¬ 
ter on Typhoid Bacillus. 
