It is well known that a culture of Bacillus coli will become sterile on standing at 37 C., as the colon bacilli are killed by the acid that they themselves produce. Test-tube experiments have shown that the acid culture fluid has a growth-inhibiting, or a deadly, effect on colon bacilli. Thus, a number of authors (Winslow and Lochridge, 1906,1 Michaelis and Marcora, 1912,2 Clark, 1915,3 Dernby, 1921,4 and Warburg and I, 1925,5) have demonstrated that the growth of B. coli is inhibited with a hydrogen ion concentration of about pH 5.
In 1921, Haldane6 showed that the urine may be acidified to a degree corresponding to about pH 5 by the oral administration of calcium chloride and ammonium chloride; and in 1924-1925, Warburg and I used this method on patients with infections of the urinary tract as a therapeutic measure against these lesions. In some cases this treatment was augmented
JOHANSEN AH. THE TREATMENT OF PYURIA DUE TO BACILLUS COLI. Arch Intern Med (Chic). 1929;44(3):303–313. doi:10.1001/archinte.1929.00140030002001