Abstract
Horwood and Webster 1 recently asked the question: “Is Escherichia coli a derivative of Aërobacter aërogenes in the human intestine?” The question was prompted by their study of Gram-negative lactose-fermenting bacteria from the ileostomy and fecal discharges of a patient. They found that 87.5% of the cultures from the ileostomy discharges were Aërobacter aërogenes, while those from the rectal discharges were all Escherichia coli.
The possibility that all members of the coliform group 2 of bacteria may be variants of only a few species of the group had been suggested to the writer by his experience with a group of 259 strains of coliform bacteria isolated differently from specimens of water, fish fillets, and feces. These strains had been carefully purified by approved methods. They were carried for 3 years on nutrient-agar slants, being transferred once each month to fresh media. Once each 6 months differential tests were made, the tests employed being the Voges-Proskauer, methyl-red, sodium-citrate, uric-acid, indol, and sodium-malonate. It was noted that many of the strains classified as Escherichia coli and as Aërobacter aërogenes remained constant in their reactions; but there was a pronounced tendency on the part of many strains, especially the intermediates, to vary in their reactions over the 3-year period.
The experience of Horwood and Webster, following as it did upon the author's experience, prompted the study reported here. The study was based upon the following assumption: If the intestinal environment is capable of inducing marked alterations in the biochemical behavior of Aërobacter aërogenes, it seemed that bile and its constituents would be likely factors in inducing these alterations. Therefore, it was the purpose of this study to determine the influence of prolonged propagation of Aërobacter aërogenes in media containing bile and bile salts, on the biochemical reactions of the organism.
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