The Longevity of Bacillus Typhosus in Natural Waters and in Sewage
Journal of Infectious Diseases
INTRODUCTION. IN a paper published in this Journal in 1904/ Jordan, Russell, and Zeit detailed an extensive series of experiments on the longevity of the typhoid bacillus in water, in which simultaneous, though independent, tests were made on this organism as exposed to the waters of Lake Michigan, the Chicago River, the Chicago Drainage Canal, and the Illinois River. The methods used in this study and the results obtained were so different from those which have previously been reported that it
... en reported that it seems desirable to test this question further, employing waters of different origin. The attempt was made in all of this work to approximate, as closely as possible, the conditions that exist in nature, and, for this reason, a marked change in technique was instituted. Heretofore, it has been customary for experiments on the longevity of bacteria to be made in glass containers, filled with sterile or raw waters. The conclusions based on work under these conditions have been shown to be erroneous, and in the work previously referred to, the method was adopted of exposing the typhoid organism in permeable sacs (celloidin and vegetable parchment), filled with the type of water in which the sacs were suspended. If, then, any variation occurred in the composition of the stream in which the sacs were exposed, the influence of such variation, if of any effect, should be felt on the imprisoned cultures within the sac. The results obtained in the experiments conducted on the Chicago Drainage Canal and other waters showed a marked variation in the vitality of B. typhosus. In the relatively pure waters of Lake Michigan, this organism could be recovered readily from the infected sacs, for a period of at least a week, while in the highly polluted waters of I Jour. Infect, Dis., 1904, I, p. 641. 4° 1. Celloidin sacs.-The celloidin sacs employed have all been made by the extremely simple method of Frost,' in which the celloidin solution is poured on the inside of the test tube and the film, after it has been air-dried for the proper time, shrunk from the glass wall by means of water. By means of this method, sacs of practically any size can be made in a few minutes. These celloidin tubes were usually made to hold about So c.c. of water. They were held in position by inserting a glass neck of. approximately the same bore as the sac, tying this on tightly with a soft-fibered thread, and coating the same with a layer of celloidin, allowing it to air dry. The sacs are filled with, as well as immersed in, water during the process of sterilization, which is done in an Arnold. 2. Parchment sacs.-In the former work sections of parchment tubing were used, such as is employed in dialysis work, but it is frequently difficult to secure tubing that is perfectly sound and free from minute holes. In this work, we have employed the parchment diffusion shells made by Schleicher and Schull, These hold approximately So c.c, and are in the form of a tube closed at one end. Into the open, free end, a glass neck is fastened by means of sealing wax. The shells themselves are sterilized in streaming steam for an hour and a half, then allowed to dry under cover from the air. The glass necks can be sterilized chemically. The two parts can be quickly assembled in a sterile condition. 3. Agar membrane sacs.-The first introduction of agar for dialyzing purposes in bacteriological studies was made by Frost," who used rectangular blocks about one-half inch square and an inch and a half long. These were made of plain agar and were inoculated by means of a stab in the center. The upper part of the stab was sealed off by dropping on melted agar, or smearing the upper surface of the block with a hot iron. Our first studies with agar were made with blocks of a similar character, but it was found that the J A mer. Pub. Health Assoc. Rep. 19°3, 28, p. 36. • Jour. Infect. 'Dis., 1904, I, p. 599 .