In March, 1882, Robert Koch announced that a tiny germ, the tubercle bacillus, was the cause of the prevalent and serious human disease known as “consumption.” From the sputum of patients having this disease he had isolated a germ so small that when magnified five hundred times it was about as thick as a fine hair. He next succeeded in growing this germ in artificial culture media. This was a great achievement because the tubercle bacillus is one of the most difficult germs to grow, requiring from five to six weeks, whereas the streptococcus which will be discussed later, can often be successfully grown over night. He then injected pure cultures of these germs into mice with the result that they developed consumption. When these mice died from the disease he found their bodies teeming with this innocent Iooking germ.
From these experiments were deduced principles known today as Koch’s Postulates, which are used fundamentally in proving all germ diseases. To prove that a germ causes a disease, one must find the germ, grow it in pure culture, produce the disease with it, and eventually when the animal dies from the disease, again isolate the germ from its tissues.
DISEASES CAUSED BY BACTERIA
The discovery of the tubercle bacillus was most important, because while germs were already known to cause some animal and plant diseases, and many leading men held a germ theory concerning human diseases, this was the first organism actually convicted of causing a human disease. This was the beginning of a brilliant period of medical discoveryheld by many to be the most important since the dawn of time. In rapid succession a long list of diseases were proved to be of germ or parasitic origin. Among the early discoveries were the organisms causing diphtheria, typhoid fever, malaria, syphilis, yellow fever, and many others. Scientists are still searching for the germs which cause smallpox, chicken pox, influenza, the common cold, and others, it being believed that they may be too small to be seen by the highest powered microscopes now in use. Largely due to the saving of lives of children and young adults through this knowledge of bacteria, the average length of life has been increased during the last 40 years by about 15 years. What has been done is well known and may be followed more in detail in any book on bacteriology.
In this chapter we wish to take up the theory of focal infection which claims that many diseases, the causes of which have been poorly understood or not known, are due to various forms of bacteria living in foci or localized areas scattered through the body. We are especially interested at this time in those states of health in which the streptococcus is present. Studies in recent years lead to the view that some complaints, such as “growing pains” in children; some forms of arthritis, and neuritis are caused more by bacterial activity in the body than by nutritional disturbances.
Streptococci Cause Heart Disease in Children. Most of the earlier work in this study, especially in this country, should be credited to the late Dr. Frank Billings of Chicago, who secured the money and planned the observations, and to his assistant, Dr. E. C. Rosenow, who made the bacteriological studies. Their first discovery pointed to a streptococcus as being a cause of the prevalent endocarditis in children. Infection caused inflammation with scarring and contraction of the delicate membranous edges of the heart valves, leading to narrowing of the valve spaces or leakage through them when closed, thus producing characteristic murmurs which were heard when one listened to the heart. From the tonsils of children with this disease, and from the blood taken during the febrile stage, and from the diseased valve leaflets when the patients died, they isolated a streptococcus which when injected into rabbits produced the same type of heart disease. Subsequent work has shown a variety of causative organisms.
Many of the patients with this type of heart disease also had what was called rheumatism at that time. There was speculation as to whether or not this rheumatism had the same cause as the endocarditis. However, in the animals inoculated with cultures from endocarditis patients, even if the patients had rheumatism also, no rheumatism developed. He therefore felt that if rheumatism was a germ disease it must be due to a different type of germ. The joint surfaces of the body contain only a limited number of blood vessels, and consequently a small amount of blood circulates in them. As a result they are poorly supplied with oxygen. He therefore theorized that the germ of rheumatism might be one that liked best to live where the oxygen supply was poor. Cultures were made from the tonsils of rheumatic patients, in especially prepared tubes. Two chemicalspyrogallic acid and sodium hydroxidewere mixed in the mouth of these test tubes after they had been sealed in with wax. The union of these two chemicals uses up oxygen. Under such conditions he sometimes found an anaerobic (growing without air) streptococcus, which when injected into rabbits produced true rheumatic joint lesions from which the original type of germs could be isolated. Unfortunately for the world, many laboratories were unable to duplicate these results obtained by Rosenow, and so considerable doubt was cast on the truth of his discoveries. It was demonstrated later that other organisms can cause infectious arthritis and we surmise that there are still undiscovered causative ultramicroscopic organisms.
In the last few years Rosenow has worked out a simple method of raising these anaerobic germs by the use of “glucose-broth-brain” media. A veal broth is used to which is added glucose and other substances which enhance the growth of bacteria. Pieces of fresh calves’ brain are cut up and placed in the broth. In this broth the brain tissue will live for a time, and because it lives it uses up oxygen. In such media as this and with no interfering chemicals that might kill the germs, as were used in the original work, other workers have grown these streptococci which like best to live in the absence of oxygen.
Streptococci in Other Diseases. Billings and Rosenow next studied ulcers of the stomach and duodenum, inflammation of the gall bladder, and appendicitis. From the tonsils and abscessed teeth of patients suffering with these diseases, and from the lesions themselves at operation, they isolated another form of streptococcus which grows most freely with very little oxygen present. When these organisms were injected into experimental animals, a large percentage of the animals developed the disease from which the patient was suffering. Rosenow then announced his “elective localization” theory (1915), which many did not believe at first because the organisms found in ulcers of the stomach, infected gall bladders, and appendices all looked alike under the microscope and grew in the test tube under identical circumstances. However, when they were injected into animals they localized in a surprisingly large percentage of cases, in the tissues corresponding to those in human beings, from which they were taken. Germs either from the tonsils of patients with ulcers, or from the ulcers themselves, usually (in 70 to 80 per cent of instances) produced ulcers in the experimental animals; similar findings were true for gall bladder and appendix infections. While this work was not confirmed in the early days it has since been confirmed by too many workers to allow any question as to its accuracy.
Arthritis. Volumes have been written on the subject of arthritis (often referred to as rheumatism) and many different classifications have been suggested. In this brief discussion it might be safe to say that the painful type of arthritis is very apt to be infectious in nature. A non-painful or mildly painful type, which is so common in advancing years, sometimes called degenerative arthritis, probably is not infectious, but is more a problem of joint injury or metabolic changes incident to age.
Gout. Gout, which frequently simulates arthritis, is believed to be a disease of metabolism, in which the blood contains more uric acid than is normal. It is usually associated with some kidney damage, which prevents the prompt excretion of uric acid with a resulting excess of uric acid circulating in the blood stream. Infection, in the opinion of some workers, may bear a relation to this kidney damage.
The Common Cold. The “Common Cold” often looked upon as of little importance, is a disease that causes an economic loss of major proportions. It is associated with increased bacterial growth in the nasal and upper respiratory tracts; but specific organisms which act as causes cannot be named at the present time.
ORIGINAL FOCI OF INFECTION
Infected Tonsils and Sinuses. With the knowledge that such serious diseases as endocarditis, “rheumatism,” pep-tic ulcer, gall bladder disease, and appendicitis could come from infections in the tonsils, physicians began advising first the removal of infected tonsils in children, and later in adults. The earlier operations on tonsils were merely a clipping of the supposedly diseased surfaces. The next step was an attempt to remove all of the tonsil, but it was soon learned that even though only a small portion of the tonsil tissue remained it would grow again, so that frequently a second “tonsil” was formed. Now we know that it is when fibrous capsule surrounding the tonsil is left that there is a regrowth. Hence the modern operation removes not only all of the tonsillar tissue, but also the fibrous capsule which surrounds each tonsil.
It was early learned that the tonsils were not the sole original source of infection. Nasal sinuses often were found to be infected. It is obvious, of course, that these should be treated.
Pulpless Teeth Usually Infected. When teeth were first X-rayed an astounding number of abscesses were found at the roots of those in which the nerves had died or had been removed. Aching or pain was not felt in these teeth. For a while dentists attempted to treat the abscesses, but eventually this was discontinued because of the failure to clear up the infection. Now patients are advised to have all abscessed teeth removed.
As early as 1925 Rosenow began to suspect the pulpless tooth which showed no changes with the X-ray as a possible source of infection. Most of these teeth when re-moved were found to be infected. In the last few years, especially since he has been at the Mayo Clinic, Rosenow has had many thousands of such teeth removed. Practically every one was found to be infected, and the germs obtained from them, in a large percentage of cases, reproduced in animals the disease of the patient.
Infection in Other Organs. Sometimes in women, an infected erosion of the cervix of the uterus, or an infected fallopian tube is the primary source of infection. In men it may be an infected prostate gland which is the primary source; however, in some instances involvement of this gland may be secondary to infections elsewhere in the body. It is conceivable that -organisms can enter the blood stream from the colon, especially if it is diseased or injured by medication.
Tonsils, devitalized teeth, nasal sinuses, cervix, fallopian tubes, prostate gland, and the colon are the commonly accepted locations of original foci of infection. Ulcers of the stomach or duodenum, infected gall bladders with or without stones, chronic appendices, and infected kidneys and bladder are often found to be secondary sources of infection.
BENEFITS FROM REMOVING INFECTIONS
Following the knowledge that the tonsils are frequently a primary source of infection, the logical removal of infected tonsils in children has been carried on for a sufficient length of time to make apparent the benefit to the present generation of children as they are growing up. There is now less heart disease, less “rheumatism,” and a decreased tendency to peptic ulcer, gall bladder disease, and appendicitis, than when infections wore on untreated.
In the routine care of any patient it is always a proper procedure to examine all common sources of infection, and advise their removal if patients are having or have had systemic diseases coming from such sources. It is also wise to advise the removal of infection in the hope that it may prevent further trouble, or the appearance of new complaints in the future.
The benefits that have come from learning that certain diseases can be cured or their effects be greatly lessened when the bacteria causing them are destroyed, leads us to watch with interest other investigations now being made in the field of bacteriology. It is not unlikely that diseases which have baffled all explanation thus far, are caused by organisms which better methods of study will make clear to observant medical workers.