SCHIZOMYCETES OR BACTERIA

Bacteria and their products are extensively used in medicine, as well as in the industries. The preparations, known as serums and vaccines are employed as specific cures for certain diseases, and are especially valuable in prophylaxis and diagnosis. Their manufacture requires great skill and special facilities are necessary to produce them. Furthermore, they can be manufactured only undergovernment license and inspection. While there are many biological products used in diagnosis, prevention and treatment, which cannot properly be placed under any definite classification, yet for the greater part these products may be grouped under two chief classes, vaccines and antiserums.

Vaccines are essentially weakened or modified viruses. The general action of vaccines is therefore preventive or prophylactic and not curative. There are several methods which may be employed in modifying or attentuating viruses. The processes involve the treatment of viruses in such ways that they may be injected into the animal body without danger of producing serious pathologic conditions, while at the same time sufficient specific infectious qualities must be present to produce mild reactions. The successful vaccine must be attenuated to the point which represents a happy medium, and which clearly indicates both safety and activity. Some of the more common methods used in attenuating viruses are attenuation by passage of the virus through some species other than the animal for which the virus is specific (smallpox vaccine); attenuation by drying at constant temperature (rabies vaccine, Pasteur) ; attenuation by growth at a temperature above the optimum (anthrax vaccine); and attenuation by chemicals.

Some of the more important vaccines are smallpox vaccine, black-leg vaccine, rabies vaccine and anthrax vaccine.

Bacterial vaccines or bacterins consist of suspensions of young, living cultures of specific bacteria which have been killed chemically or by the application of moist heat at a temperature slightly above their thermal death point. Wright and Douglas  first advanced the theory of opsonic action and suggested that the subcutaneous injection of a given species of bacteria which had been killed, conferred to the blood of the treated individual greater opsonic activity towards the species of organisms in question. The opsonic activity is expressed by the degree of readiness with which the phagocytes destroy invading micro-organisms. Bacterial vaccines may be used in the formof orstockvaccines. An or" " autogenous autogenous personal vaccine is one prepared from a culture of the specific organism iso lated from the patient in question. Stock bacterial vaccinesarepre pared from stock cultures of the various organisms. The latter may be manufactured and stored until required for treatment. Some of the more common 'bacterial vaccines are typhoid (especially as a prophylactic), streptococcus, staphylococcus, streptococcus and staphylococcus combined, gonococcus, pertussis, acne, colon, canine distemper and equine influenza.

Tuberculins are preparations made from the human and bovine strains of Bacterium tuberculosis and are used both in diagnosis and treatment. Koch's Tuberculin (Old) is the concentrated, glycerinated beef bouillon, in which the tuberculosis organism has been grown. The active substance of the Tuberculin, which is apparently an albuminous derivative insoluble in alcohol, is elaborated by the organisms during their multiplication. In human, as well as in veterinary practice, Tuberculin may be applied as a diagnostic agentin various ways. In addition to the hypo dermatic injectionof Tuberculin Old, the methods of Calmette, von Pirquet and Moro may be used. Calmette's 'test consists in the instillation in the eye of Koch's Tuberculin Old which has been prepared by precipitating and washing the resulting precipitate. Von Pirquet's reaction depends upon the cutaneous application of Tuberculin Old, while Moro's modification of von Pirquet's method consists in the use of Tuberculin Ointment, which is vigorously rubbed on a small area of the skin. A positive reaction is evidenced by the appearance of an eruption at the point of application after about twenty-four hours. Tuberculin T. R. (tuberculin residuum) is prepared by repeatedly centrifugalizing a suspension in water of the dried and ground tubercle organisms. Tuberculin B. E. (bacillary emulsion) is com- posed of a suspension of crushed or thoroughly ground tubercle organ- isms in 50 per cent glycerin solution. Tuberculin T. R. and Tuber- culin T. E. are used as therapeutic agents, and are administered subcutaneously.

Antitoxic and antimicrobial serums are prepared from the blood of animals which have been immunized by repeated injections of specific organisms, in live or dead condition, or by repeated treatments with specific bacterial toxins. Antiserums may be employed in the form of liquid or dried serums or as precipitated globulins. The immunity induced by the use of antiserums is passive in nature. In other words, the protective material or antibodies are furnished to the treated individual ready-made, therefore the immunity which follows is relatively temporary. Antitoxic serums consist of those serums which are prepared from animals, treated with repeated doses of the specific toxins. The antibacterial serums, which are not as specific as the antitoxic, are the result of the treatment of the animals with increasing doses of the dead, attenuated or live bacteria. The important antitoxic serums are the antidiphtheritic and antitetanic, while the antibacterial serums are the antigonococcic, antimenin-gococcic, antistreptococcic and antituberculic."

In an interesting work entitled nik off advanced the theory that duration of life may be prolonged if measures were taken to control intestinal putrefaction. He found that there was a widespread popular belief in the advantage of a diet consisting largely of sour milk, and that there was a fair parallel between unusual longevity and such a diet. He also observed that the cause of much sickness and debility was due by reason of gastro-intestinal autointoxication. It can be demonstrated by laboratory and clinical experiments that the lactic acid, due to the action of Bacillus lactis acidi, in the beverages known as koumys, kefir yoghurt, rapi and buttermilk, tend to inhibit intestinal putrefaction. It has been found that the organism causing Bulgarian sour milk is especially active in lactic acid production. This organism, known as Bacillus bulgaricus, is now prepared commercially on a rather large scale and sold in the form of tablets. The tablets, consisting of slowly dried cultures mixed with milk sugar, are taken as such or after having been added to sterile milk, thus effecting the souring of thesame. In addition to tablets of Bacillus lactisacidi and Bacillus bulgaricus, a mixture of bacteria and yeast capable of producing lactic acid fermentation of milk is sold under the name of " Kefir Carter has made an examination of commercial cultures fungi." of Bulgarian Bacillus. (Jour. A. Ph. A., 1919, 8 p. 179.)

Very great interest has been aroused in the manufacture of nitrogen-fixing bacteria in cultures for the use of farmers. Probably no question is of greater fundamental importance to the agri-culturist than the supply of nitrogen to the soil. It has been known for very many years that nearly all other plants except the Leguminosase (clover, alfalfa, soy beans, etc.) rob the soil of its nitrogen while plants of this family serve to enrich it in nitrogen, hence they" have been called collectors or accumulators of nitrogen." For more than a century it was known that the Leguminosse produced nodules or tubercles on their roots which were supposed to be evidences of disease in the plants. In 1836 Treviranus found that these nodules were normal growths, and in 1865 Woronin discovered in them cells that were filled with bacteria. Hellriegel in conjunction with Wilfarth carried on a number of investigations and arrived at the in controvertible conclusion that the production of nitrogen by leguminous crops was through the absorption of atmospheric nitrogen and connected with the development of the nodules on the roots of these plants. Beyerinck in 1888 isolated the bacteria and studied them and their products in artificial media. The organism found in the nodules on the roots of the Leguminosa 3 is a single species of bacillus known as Pseudomonas radicola. Prazinowski in 1889 inoculated pure cultures into leguminous roots with successful results, and since that time very much work has been done by manufacturers to supply farmers growing leguminous crops with cultures of nitrogen-fixing bacteria which would give them the maximum yield of crops. This is particularly important where the leguminous crops are used in rotation in a soil where the nitrogen-fixing bacteria are desirable.

In the brief space allotted in a few pages it is impossible to adequately cover even the more important phases of applied bacteriology. Mention cannot be made of many products which are based upon the presence of bacteria or which are due to bacterial action, neither can a detailed discussion be given relative to many industrial operations which depend upon bacterial activity, such as the curing of vanilla, the fermentation of tobacco, the manufacture of vinegar, the tanning of hides, the ripening of cheese and the retting of flax.

To-day the study of Bacteriology as an applied science is becoming so broad that it consists of several special branches, the most important of which are Bacteriology in relation to Disease of Animals and Plants, Dairy Bacteriology, Soil Bacteriology, Bacteriology in relation to Water Supply and Sewage Disposal, and Household Bacteriology.

Soure: Scientific and applied pharmagognosy by Henry Kraemer, New York, John Wiley & Sons, Inc. London: Chapman & Hall, Limited 1920