Tubercle bacillus

“ In films stained by Gabbet's method tubercle bacilli, if present, will be seen as slender red rods upon a blue background of mucus and cells (Plate II, Fig. 2) . They average 3 to 4 μ in length—about one-half the diameter of a red blood-corpuscle. Beginners must be warned against mistaking the edges of cells, or particles which have retained the red stain, for bacilli. The appearance of the bacilli is almost always typical, and if there seems room for doubt, the structure in question is probably not a tubercle bacillus. They may lie singly or in groups. ”

“ It does not flourish equally well in the bodies of all human beings.
When once it gains lodgment in a body suited to its growth it multiplies slowly, each germ dividing and subdividing, taking from the tissues material for its growth, and returning to them certain subtle poisons which it sets free. The action of the tubercle bacillus is peculiar in that it stimulates the cells of the body, wherever it may lodge and grow, to the formation of little masses of new tissue, which we call tubercles. These tubercles are as a rule short-lived, and, if the disease progresses, tend to disintegrate. ”

“ Other bacteria than the acid-fast group are stained blue by Gabbet's method. Those most commonly found are staphylococci, streptococci, and pneumococci. Their presence in company with the tubercle bacillus constitutes mixed infection, which is much more serious than single infection by the tubercle bacillus. It is to be remembered, however, that a few of these bacteria may reach the sputum from the upper air-passages. Clinically, mixed infection is evidenced by fever. ”

“ Animal experiments have shown that both meat and milk derived from tuberculous cattle are capable of conveying infection. The precise degree of danger to human beings from the use of these foods under modern conditions is still in dispute. Since the tubercle bacillus of bovine origin differs from the tubercle bacillus of human origin in certain well-defined particulars, it is possible by careful study to distinguish the human infections caused by the bovine bacillus from those caused by the so-called human tubercle bacillus. ”

“ Whether the body at one time affords a congenial soil to the invading germs and at another does not, whether its marvelous and complex powers of resisting the virulent tendencies of disease-producing bacteria at one period or in one individual are more vigorous than in another, and vary at different times, we do not certainly know. This, however, we do know, that certain individuals are more likely than others to yield to the incursions of the tubercle bacillus. ”

“ All these modes of extension are well shown in tuberculosis. This disease is caused by a small bacillus which does not produce spores, has no power of saphrophytic growth under natural conditions, and is easily destroyed. Moisture and darkness are favorable conditions for its existence, sunlight and dryness the reverse. There are three varieties or strains of the tubercle bacilli which infect respectively man, cattle and birds, and each class of animals shows considerable resistance to the varieties of the bacillus which are most infectious for the others. ”

“ There is no doubt that the widespread popular interest and agitation against tuberculosis has overemphasized the importance of the tubercle bacillus, and the diagnosis and care of tuberculous patients. But equally or even more important is the prevention of the disease by sanitation, personal hygiene and increase of individual resistance to it. The bacilli, as Osler says, are ubiquitous, and practically every person is exposed at some time to infection. ”

“ The last named, seen in inoculated rabbits, have been held to establish a relationship between the microbes of tuberculosis and actinomycosis, as the club-shaped cells do not take the usual Ziehl-Neelsen stain for tubercle bacilli, but the Birsch-Hirshfeld’s actinomyces stain. Apart from the rabbit such variations are not likely to prove sources of fallacy in identification of the microbe.
Morphology. As met with in the tubercle of man or ox the bacillus is a minute rod with rounded ends, 1.5 to 3.5μ long, by 0.2μ in thickness. In the ox it is shorter and thicker on an average than in man. ”

“ Ordinarily, no attempt is made to identify any but the tubercle bacillus and the gonococcus.
Tubercle bacilli are nearly always present in the urine when tuberculosis exists in any part of the urinary tract, but are often difficult to find, especially when the urine contains little or no pus.
Detection of Tubercle Bacilli in Urine.—The urine should be obtained by catheter after careful cleansing of the parts.
(1) Centrifugalize thoroughly, after dissolving any sediment of urates or phosphates by gentle heat or acetic acid. Pour off the supernatant fluid, add water, and centrifugalize again. ”

“ Mr. H. Swithinbank has been carrying out an elaborate investigation into the effects produced on tubercle bacillus by exposure to the cold of liquid air. He finds that prolonged exposure to that temperature, and even actual soaking in liquid air, has little or no effect on the vitality of the bacillus, though its virulence is to some extent modified. ”

“ Tubercle bacillus--Methods of infection--Inherited and acquired
predisposition--Relationship of tuberculosis to injury--Human and bovine tuberculosis--Action of the bacillus upon the tissues--Tuberculous granulation tissue--Natural cure--Recrudescence of the disease--THE TUBERCULOUS ABSCESS--Contents and wall of the abscess--Tuberculous sinuses. Tuberculosis occurs more frequently in some situations than in others; it is common, for example, in lymph glands, in bones and joints, in the peritoneum, the intestine, the kidney, prostate and testis, and in the skin and subcutaneous cellular tissue ”

“ The tubercle bacillus is primarily and essentially one, but this must not close our eyes to the fact that in different hosts and environments it takes on very different habits, so that for the time and in these surroundings, it is materially modified in its pathogenic attitude toward different races. Yet its ready variability when conditions are favorable to change, renders it desirable to destroy it in all its forms, and especially in those which approximate most closely to those that prey on man and animals. ”

“ The terrible disease tuberculosis is the most serious and deadly enemy which the human body has to face. It kills every year, in the United States, over a hundred and fifty thousand men, women, and children—more lives than were lost in battle in the four years of our Civil War. It is caused by a tiny {157}germ—the tubercle bacillus—so called because it forms little mustard-seed-like lumps, or masses, in the lungs, called tubercles, or "little tubers." ”

“ The most widely distributed pathogenic microörganism (disease-causing bacterium) in the air is the tubercle bacillus, the cause of consumption and a large variety of other ailments, such as hipjoint disease, caries of the spine, etc. Over one hundred thousand persons die annually from consumption alone in the United States, and it is estimated that there are over two million people afflicted with the disease in one form or another. ”

“ Tuberculous infections are extremely common, much commoner even than their high mortality reveals. After long and critical discussion with a number of persistent denials, it is now generally conceded by authorities in the disease that the old maxim "after all, all of us are a little tuberculous" is substantially correct. Very few human beings entirely escape infection from the tubercle bacillus at some time in life. ”

“ Tuberculosis may be produced artificially by injecting the tubercle bacillus into animals, some being much more susceptible than others. Milk drawn from an udder in which there are breaking-down tuberculous foci, may contain an enormous number of active tubercle bacilli; and pigs fed upon this milk develop a typical tuberculosis, commencing in the glands of the throat, which can be traced from point to point, with the utmost precision. It must be assumed that what takes place in the pig may also take place in the human subject ”

“ The tubercle bacilli produced when growing in living tissues, the same as in artificial cultivations, contain substances which variously and notably unfavorably influence living elements in their vicinity. Among these is a substance which in a certain degree of concentration kills or so alters living protoplasm that it passes into a condition that Weigert describes as coagulation necrosis. In tissue thus become necrotic the bacillus finds such unfavorable conditions of nourishment that it can grow no more and sometimes dies. ”

“ In the second place, the body must be predisposed to the disease by various unhealthful factors, such as vicious heredity, alcoholism, poverty and the like. Most of us are able to resist the bacillus because our bodies are sufficiently strong to resist the organism, and because there are in our tissues certain germicidal properties, which are ordinarily sufficient to cope with and destroy the bacillus. The layman will easily get the idea from the following experiment: Some rabbits were inoculated with tubercle bacilli and placed in relations generally deleterious to health ”

“ Thus the tubercle bacillus may cause a limited growth of connective tissue and as especially Borrel has pointed out the organisms causing smallpox and vaccinia may even produce a slight proliferation of the infected epithelium. But in all those cases the proliferation soon ceases and toxic substances produced by bacteria lead usually soon to the death of a great part of the newly-formed cells.
Based on such considerations many attempts have been made to prove the constant presence of certain parasitic microorganisms in human cancer. ”

“ The tubercle bacillus is a little colourless, rod-like plant, so small that even many thousands of them piled together would make a heap far too small to be visible to the naked eye. It cannot move about, nor can it grow without moisture, nor at a temperature much above or much below that of the human body. The [Pg 69] material on which it feeds must be very nicely adapted to its requirements, and it has no lurking and growing places in nature outside of the bodies of men and a few warm-blooded animals. ”

“ A pure culture of bacteria will not necessarily require the counter-stain (methylene-blue) . Sections of tissue may require twenty to thirty minutes in the primary stain (carbol-fuchsin) . This stain is used for tubercle and leprosy. With a little practice the staining of the bacillus of tubercle when present in pus or sputum becomes a very simple and accurate method of diagnosis. A small particle of sputum or pus is placed between two clean cover-glasses and thus pressed between the thumb and finger into a thin film. ”

“ The anthrax bacillus may retain its vitality for several years in a desiccated state. Clearly, therefore, desiccation has no administrative value in the prevention of disease, and on the contrary it aids the dissemination of the microbes of tuberculosis, small-pox, scarlet fever, etc.
Direct Sunlight kills a large proportion of the sporeless pathogenic microbes. Diffuse is less energetic in its action than direct sunlight. The bacillus of diphtheria is destroyed by a half to one hour’s exposure to sunlight. As to tubercle bacilli, see page 316. ”

“ On this view the answer to the question, Can the bovine bacillus affect man? is obviously in the affirmative. The same answer must also be given to those who hold the theory that human and bovine tubercle bacilli are different in kind, since the ' bovine kind ' are readily to be found as the causal agents of many fatal cases of human tuberculosis. ”

“ That the bacillus of consumption should have been very frequently found in dust by different investigators is hardly surprising when it is realised that the sputum of phthisical persons may contain the tubercle germ in large numbers, and that until recently no efforts have been made in this country to suppress that highly objectionable and most reprehensible practice of indiscriminate expectoration. ”

“ Stain with carbol-fuchsin, steaming, for at least three minutes.
(4) Wash in water, and then in 20 per cent. nitric acid until only a faint pink color remains.
(5) Wash in water.
(6) Soak in alcohol fifteen minutes or longer. This decolorizes the smegma bacillus (p. 35) , which is often present in the urine, and might easily be mistaken for the tubercle bacillus. It is unlikely, however, to be present in catheterized specimens. It is always safest to soak the smear in alcohol for several [p. 128] hours or over night, since some strains of the smegma bacillus are very resistant. ”

“ In my own laboratory, recent experiments made with the bacillus of glanders have shown that when grown in a slightly acid medium containing alkali-albuminate, albumoses, peptones, and crystalline bodies such as leucin and tyrosin are formed in considerable quantities. Kresling162 has reported similar results. With the tubercle-bacilli, many like results have been recorded. Thus, among others, Crookshank and Herroun163 have reported the finding of albumoses, peptone, and a ptomaine when the bacilli have been grown in glycerin agar-agar, and also in fluid media. ”

“ Some new light has been thrown upon the subject of pathogenic organisms in air by Neisser in his investigations concerning the amount and rate of air-currents necessary to convey certain species through the atmosphere. He states that the bacteria causing diphtheria, typhoid fever, plague, cholera, and pneumonia, and possibly the common Streptococcus pyogenes, are incapable of being carried by the molecules of atmospheric dust which the ordinary insensible currents of air can support, whilst Bacillus anthracis, B. pyocyaneus, and the bacillus of tubercle are capable of being aërially conveyed. ”