FIG. 6
Dental Caries. Tubules Plugged with Cocci. × 500. (Miller.)
Upper Respiratory Tract.
—The oral cavity and pharynx are seldom free from bacteria. Miller has studied over one hundred species that he has found under various circumstances in the human mouth. Some of these are pathogenic; others are apparently absolutely innocent. Many of the forms which grow in saliva will not grow in ordinary media. (See [Plate III], illustrating infection of the teeth.) Miller has also shown that many forms of dental caries are but expressions of bacterial invasion even of those apparently most solid structures, the teeth; and of late we have been taught more fully that such invasion may extend far beyond the confines of the teeth alone, and may spread to various, even to distant parts, and produce possibly fatal mischief. Abscesses in the brain and extensive septic infections have been traced to invasion along the line of the dental tubules. One of the most virulent of all the common inhabitants of the mouth is the pneumococcus of Fränkel, known also as the micrococcus lanceolatus of Stebernrg. In virulence it is a variable organism, but it is present in a virulent state in only 12 or 15 per cent. of cases of infection due to it. This is the organism which is the cause of lobar pneumonia, and frequently of bronchopneumonia, as well as of numerous phlegmons and other inflammations of the throat, and which, getting into the general circulation through the tonsils or other possible ports of entry about the mouth, causes serious septic and inflammatory disturbances in widely distant regions. Aside from dental caries, a widely opened port of entry is often afforded by those ulcerations around the margins of the gums which are produced by accumulations of tartar. Disease in the antrum of Highmore, for instance, and many other local destructions, are frequently caused in this way.
The next most common port of entry is the tonsils, faucial, lingual, and pharyngeal, which contain a variety of crypts which are often filled with secretions or retentions loaded with bacteria. One of the most common sources of an involvement of the cervical lymph nodes in tuberculous disease is an infection springing first from the tonsils or the teeth.
In spite of the fact that myriads of bacteria are swept into the nasal cavities with the air we breathe, few are seen in the nose. A peculiar capsule bacillus, closely allied to that described by Friedländer, has been found in a number of cases of ozena, while the pneumococcus of Fränkel is also often found there, and is known to produce abscesses of the brain. One specific organism—namely, that of rhinoscleroma—concerns the nose almost solely, its first ravages being met with in this location.
Alimentary Canal.
—Probably more microörganisms enter the alimentary canal than gain access in any other way, these coming both from food and drink as well as air. Once within its confines, few of them are capable of prolonged existence. Welch states that the meconium of newborn infants is sterile, but that within twenty-four hours it usually contains abundant bacteria. That bacterial infection through this passage-way is a fertile source of non-surgical lesions is well known. The possibility of surgical infections being produced in the same way is both more remote and less demonstrable. Naturally, anaërobic organisms find here more favorable conditions, and even extremely acid or extremely alkaline conditions do not serve to destroy all such life. Pyogenic cocci are often present and are frequently found in peritoneal exudates. In the intestines of herbivorous animals the tetanus bacilli and those of malignant edema are regularly found. The fungus of actinomycosis also finds its way into the bowel along with ingested food. Under ordinary conditions the bile in its natural reservoirs is free from bacteria, but the colon bacilli and pyogenic cocci often invade these precincts.