Alexis Thomson

“ Those that require oxygen are known as _aerobic bacilli_ or _aerobes_; those that cannot live in the presence of oxygen are spoken of as _anaerobes_. The great majority of bacteria, however, while they prefer to have oxygen, are able to live without it, and are called _facultative anaerobes_. ”

“ The actual number of organisms introduced is also an important factor in determining their pathogenic power. Healthy tissues can resist the invasion of a certain number of bacteria of a given species, but when that number is exceeded, the organisms get the upper hand and disease results. When the organisms gain access directly to the blood-stream, as a rule they produce their effects more certainly and with greater intensity than when they are introduced into the tissues. ”

“ There is evidence that a _mixed infection_--that is, the introduction of more than one species of organism, for example, the tubercle bacillus and a pyogenic staphylococcus--increases the severity of the resulting disease. If one of the varieties gain the ascendancy, the poisons produced by the others so devitalise the tissue cells, and diminish their power of resistance, that the virulence of the most active organisms is increased. ”

“ From the study of the processes by which immunity is secured against the effects of bacterial action the serum and vaccine methods of treating certain infective diseases have been evolved. The _serum treatment_ is designed to furnish the patient with a sufficiency of antibodies to neutralise the infection. The anti-diphtheritic and the anti-tetanic act by neutralising the specific toxins of the disease--_antitoxic serums_; the anti-streptcoccic and the serum for anthrax act upon the bacteria--_anti-bacterial serums_. ”

“ It is of high vitality and resists more prolonged exposure to high temperatures than most non-sporing bacteria. It is capable of lying latent in the tissues for long periods, for example, in the marrow of long bones, and of again becoming active and causing a fresh outbreak of suppuration. This organism is widely distributed: it is found on the skin, in the mouth, and in other situations in the body, and as it is present in the dust of the air and on all objects upon which dust has settled, it is a continual source of infection unless means are taken to exclude it from wounds. ”

“ The influence of micro-organisms in the causation of disease, and the role played by them in interfering with the natural process of repair, are so important that the science of applied bacteriology has now come to dominate every department of surgery, and it is from the standpoint of bacteriology that nearly all surgical questions have to be considered. ”

“ Leucocytosis is met with in nearly all acute infective diseases, and in acute pyogenic inflammatory affections, particularly in those attended with suppuration. In exceptionally acute septic conditions the extreme virulence of the toxins may prevent the leucocytes reacting, and leucocytosis may be absent. The absence of leucocytosis in a disease in which it is usually present is therefore to be looked upon as a grave omen, particularly when the general symptoms are severe. In some cases of malignant disease the number of leucocytes is increased to 15,000 or 20,000. ”

“ The most suitable temperature for bacterial life is from 95 to 102 F., roughly that of the human body. Extreme or prolonged cold paralyses but does not kill micro-organisms. Few, however, survive being raised to a temperature of 134.5 F. Boiling for ten to twenty minutes will kill all bacteria, and the great majority of spores. Steam applied in an autoclave under a pressure of two atmospheres destroys even the most resistant spores in a few minutes. Direct sunlight, electric light, or even diffuse daylight, is inimical to the growth of bacteria, as are also Rontgen rays and radium emanations. ”

“ A _polyvalent_ serum, that is, one derived from an animal which has been immunised by numerous strains of the organism derived from various sources, is much more efficacious than when a single strain has been used. ”

“ Conditions of Bacterial Life.#--Bacteria require for their growth and development a suitable food-supply in the form of proteins, carbohydrates, and salts of calcium and potassium which they break up into simpler elements. An alkaline medium favours bacterial growth; and moisture is a necessary condition; spores, however, can survive the want of water for much longer periods than fully developed bacteria. The necessity for oxygen varies in different species. ”

“ Outside the body, bacteria may be killed by starvation, by want of moisture, by being subjected to high temperature, or by the action of certain chemical agents of which carbolic acid, the perchloride and biniodide of mercury, and various chlorine preparations are the most powerful. ”

“ From the point of view of the surgeon the most important varieties of micro-organisms are those that cause inflammation and suppuration--the _pyogenic bacteria_. This group includes a great many species, and these are so widely distributed that they are to be met with under all conditions of everyday life. ”

“ Lastly, in patients suffering from chronic wasting diseases, bacteria may invade the internal organs by the blood-stream in enormous numbers and with great rapidity, during the period of extreme debility which shortly precedes death. The discovery of such collections of organisms on post-mortem examination may lead to erroneous conclusions being drawn as to the cause of death. ”

“ In the human subject, multiplication in the blood-stream does not occur to any great extent. In some general acute pyogenic infections, such as osteomyelitis, cellulitis, etc., pure cultures of staphylococci or of streptococci may be obtained from the blood. In pneumococcal and typhoid infections, also, the organisms may be found in the blood. ”

“ This condition of the blood, which is known as _leucocytosis_, is believed to be due to an excessive output and rapid formation of leucocytes by the bone marrow, and it probably has as its object the arrest and destruction of the invading organisms or toxins. To increase the resisting power of the system to pathogenic organisms, an artificial leucocytosis may be induced by subcutaneous injection of a solution of nucleinate of soda (16 minims of a 5 per cent. solution) . ”

“ Results of Bacterial Growth.#--Some organisms, such as those of tetanus and erysipelas, and certain of the pyogenic bacteria, show little tendency to pass far beyond the point at which they gain an entrance to the body. ”

“ The conditions which render a person liable to develop anaphylaxis and the mechanism by which it is established are as yet imperfectly understood.
_Vaccine Treatment._--The vaccine treatment elaborated by A. E. Wright consists in injecting, while the disease is still active, specially prepared dead cultures of the causative organisms, and is based on the fact that these "vaccines" render the bacteria in the tissues less able to resist the attacks of the phagocytes. ”

“ It is by the vital changes they bring about in the parts where they settle that micro-organisms disturb the health of the patient. In deriving nourishment from the complex organic compounds in which they nourish, the organisms evolve, probably by means of a ferment, certain chemical products of unknown composition, but probably colloidal in nature, and known as _toxins_. ”

“ In this connection it must be understood that "rest" implies more than the mere state of physical repose: all physiological as well as mechanical function must be prevented as far as is possible. For instance, the constituent bones of a joint affected with tuberculosis must be controlled by splints or other appliances so that no movement can take place between them, and the limb may not be used for any purpose ”