Bacteria: Chapter II - BACTERIA IN WATER

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Hence we must use common sense in the selection and obtaining of a sample, following this one guide, namely, to collect as nearly as possible a sample of the exact water the quality of which it is desired to learn. In the second place, we must observe strict bacteriological cleanliness in all our manipulations. This means that we must use only sterilised vessels or flasks for collecting the sample, and in the manipulation required we must be extremely careful  collected water from various quarters at various times and seasons, and some of his results may here be added:Again, another example:"During the summer months these waters are purest as regards micro-organisms, this being due to the fact that during dry weather these rivers are mainly composed of spring water, whilst at other seasons they receive the washings of much cultivated land."—FranklandPrausnitz has shown that water differs, as would be expected, according to the locality in the stream at which examination is made. His investigations were made from the river Isar before and after it receives the drainage of Munich:Professor Percy Frankland also points out how the river Dee affords another example, even more perfect, of pollution and restoration repeated several times until the river becomes almost bacterially pure.We cannot here enter more fully into the many conditions of a water which affect its bacterial content than to say that it varies considerably with its source, at different seasons, and under different climatic conditions. An enormous increase will occur if the sediment is disturbed, and conversely sedimentation and subsidence during storage will greatly diminish the numbers of bacteria. Sand filtration, plus a "nitrifying layer," will remove more than 90 per cent. of the bacteria. Sea-water contains comparatively few bacteria, and the deeper the water and the farther it is from shore so much less will be the bacterial pollution.the chief disease organisms found in waterBacteria of Typhoid Fever

Microscopic Characters (in pure culture). Rods, 2–4 µ long, .5 µ broad, having round ends. Sometimes threads are observable, being 10 µ in length. In the field of the microscope the bacilli differ in length from each other, but are all the same thickness approximately. Round and oval cells constantly occur even in pure culture, and many of these shorter forms of typhoid are identical in morphology with some of the many forms of Bacillus coli.

There are no spores. Motility is marked; indeed, in young culture it is the most active pathogenic germ we know. The small forms dart about with extreme rapidity; the longer forms move in a vermicular manner. Its powers of movement are due to some five to twenty flagella of varying length, some of them being much longer than the bacillus itself, though, owing to the swelling of the bacillus under flagellum-staining methods, found that when they examined specially infected typhoid sewage it was only with extreme difficulty they isolated Eberth's bacillus. In ordinary sewage it is clear such difficulty would be greatly enhanced.B. Coli Communis

We have pointed out elsewhere the relation between soil and typhoid. In water, even though we know it is a vehicle of the disease, the Bacillus typhosus has been only very rarely detected. The difficulties in separating the bacillus from waters (like that at Maidstone, for example), which appear definitely to have been the vehicle of the disease, are manifold. To begin with, the enormous dilution must be borne in mind, a comparatively small amount of contamination being introduced into large quantities of water.

Secondly, the huge group of the B. coli species considerably complicates the issues, for it copiously accompanies the typhoid, and is always able to outgrow it. Further, we must bear in  as the vehicle of typhoid, even though no typhoid bacilli were discoverable.

The chief of these sewage bacteria are believed to be Proteus vulgaris, B. coli, P. zenkeri, and B. enteritidis, and they are all nearly related to B. typhosus. The presence of the B. coli in limited numbers is not suffi as follows

1. Bacillus coli communis and all its varieties and allies.

2. Proteus vulgaris and the various protean species.

3. B. enteritidis sporogenes (Klein).

4. Liquefying bacteria, e. g., Bacillus fluorescens liquefaciens, B. subtilis, B. mesentericus.

5. Non-liquefying bacteria.6. Sarcinæ, yeasts, and moulds.

We have not included in the above inventory any pathogenic bacteria. Doubtless such species (e. g., typhoid) not infrequently find their way into sewage. But they are not normal habitants, and though they struggle for survival, the keenness of competition among the dense crowds of saprophytes makes existence almost impossible for them. Nor can they expect much sympathy from us in the difficulties of life which fortunately confront them in sewage.

Of those we have named as normally present it is unnecessary to speak in detail, with the exception of the newly  This bacillus is credited to be a causal agent in diarrhœa, and has been isolated by Dr. Klein from the intestinal contents of children suffering from severe diarrhœa, and from adults having cholera nostras. It has been readily detected in sewage from various localities, and also in sewage effluents, after sedimentation, precipitation, and filtration. Its biological characters are shortly as follows: It is in thickness somewhat like the bacillus of symptomatic anthrax, thicker and shorter than the bacillus of malignant œdema, and standing therefore between the latter and anthrax itself. It is motile and possesses flagella, but has no threads. It readily forms spores, which develop as a rule near the ends of the rods and are thicker than the bacilli. It is stained by Gram's method. In various media (particularly milk) it produces gas rapidly. It is an anaërobe, and is cultivated in Buchner's tubes. A recent epidemic of diarrhœa affecting 144 patients in St. Bartholomew's Hospital was traced to milk in which B. enteritidis was present.

Sewer Air. Though not of material importance as regards bacterial treatment of sewage, this subject calls for some remark. For long it has been known that air polluted by sewage emanations is capable of giving rise to various degrees of ill-health. These chiefly affect two parts of the body; one is the throat, and the other is the alimentary canal. Irritation and inflammation may be set up in both by sewer air. Such conditions are in all probability produced by a lowering of the resistance and vitality of the tissues, and not by either a conveyance of bacteria in sewer air or any stimulating effect upon bacteria exercised by sewer air. What evidence we have is against such factors. (See p. 105.)

Several series of investigations have been made into the 

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