The Value of Methods for the Differentiation of Bacilli of the Coli-aerogenes Group, when Applied in Shanghai

Abstract

1. A collection was made of organisms of the coli-aerogenes group; 100 from the human intestine, 50 from animals, and 50 from the soil. To these were applied the indol test, the methyl red and Voges-Proskauer tests, and Koser' citrate test. The citrate test was also applied to certain non-lactose fermenters. 2. 89·4 per cent. of 150 faecal organisms gave the combination of a failure to grow in citrate solution, the production of indol, an acid reaction with methyl red and a negative Voges-Proskauer reaction. 3. There is a probability that some faecal organisms have crept into the “soil” series, but the contamination is not heavy enough to make the results useless. The figures show that the citrate and indol test are both useful, the citrate being a little better. The methyl red and Voges-Proskauer reactions were not helpful. 4. In the bacteriological examination of water in Shanghai it is safe to take those organisms which can grow in citrate but do not produce indol as being non-faecal.