Following conclusions are based upon a study of 1075 cases, comprising chil dren of all ages from one to eighteen years, among whom were encountered 134 cases of clinical diphtheria and from whom were obtained 8000 cultures. Ot these children, 275 were kept in absolute individual isolation, and under condi tions admitting of the most careful over sight, in which tbe chances of reinfection were reduced to the minimum. While the Klebs-Loeffier bacillus is undoubtedly present along with staphylococci and several other varieties of bacilli in every case of diphtheria, its mere presence is no guide as to its virulence or non virulence. This bacillus, or one morpho logically identical with it, is present in the throats in nearly one-third of all the children and possibly adults. It is found as frequently in the throats and noses of those who have never had clin ical diphtheria as in those who have sus tained acute attacks of the disease, but in the former is often of valiant type. J. H. Adair (Northwestern Lancet, Sept. 1, '99).
From a study of the throat cultures of 285 healthy individuals, 7 of which showed the presence of diphtheria bacilli, and of 190 healthy boys whose throat cultures showed the presence of the Klebs-Loeffler bacilli in only 16, the fol lowing conclusions have been drawn: 1. Diphtheria bacilli are seldom found in the throats of those who have not been exposed to diphtheria. 2. The bacilli are more frequently found in those who have been exposed, especially in persons living under poor hygienic conditions or in institutions. 3. The conditions of • institution life which favor the growth of the bacilli in healthy throats are the living together of a large number of persons in a limited air-space. 4. Healthy individuals with virulent bacilli in their throats can spread the disease. They are just as dangerous as mild or convalescent eases of diphtheria, and ought, therefore, to be detected and isolated. 5. Cultures ought to be made among those who have been exposed to diphtheria; (a) by- physicians among the members of a family who have been exposed; (b) by inspectors in the schools; (c) by the health officers under any circumstances when they think the disease is being or may be spread by such individuals. F. P. Denny- (Boston Med. and Surg. Jour., Nov. 22, 1900).
Not only are there definite and dis tinct species of diphtheria bacillus, but each species has distinct subspeeies and varieties with characteristics which con tinue to persist under different condi tions. Thus, varieties as well as spe cies remain separate, and when grown under similar conditions the species show no tendency to become converted the one into the other, while the varie ties gradually change, approaching a common norm. Since in a series of ten cases of clinically typical diphtheria only one variety of the specifically viru lent diphtheria ba-eillus was obtained from the throat of each case through out the course of the disease, since from different parts of the same patient only 011C variety was isolated, and since pseudovarieties were found no mare fre quently at the end than at the begin ning of the disease, it is safe to infer that specifically virulent bacilli do not readily, if ever, change into any form of non-virulent diphtheria bacilli in throats or noses of people during an attack of diphtheria, In a second group a number of healthy throats were ex amined and many distinct varieties of diphtheria-like bacilli were found, all of which, however, in serial pure culture, retained their characteristics. From a third group the inference was drawn that not only does a variety of the ba cillus retain its eharacteristies for some time in the same throat, but that it may be transferred to other throats without losing its individuality. Finally
a number of cultures were examined which had been kept in the laboratory for years. These WCIT freshly inocu lated every few days, and but few changes were found in the general shape and properties of the bacilli, as com pared with the original observation. A. 'W. Williams (Jour. of Med. Research, June, 1902).
2. Pseudodiphtheria, in which we in clude all cases resembling diphtheria but not showing the presence of the diphtheria bacillus in cultures from the affected parts. Such pseudomembra uous inflammations are commonly seen as complications of the acute infectious diseases, especially scarlet fever and measles. Cultures from such cases regu larly show the presence of streptococci or staphylococci or both. The strepto cocci are especially frequent. Pneumo cocci and other bacteria have been found.
The site of the diphtheritic process, whether nose, tonsils or pharynx, or larynx, materially affects the symptoms and course of the disease; we therefore, in our description, speak of nasal; pharyngeal, or tonsillar; and laryngeal diphtheria. In the effort to further classify their cases some divide them upon the basis of the bacteriological findings in cultures from the throat. Thus, when the culture shows diph theria bacilli practically alone, they designate the case as bacillary diph theria; when cocci are present in con siderable numbers with the diphtheria bacilli, as coccobacillary diphtheria, etc. This method would be highly satisfactory did the clinical course and outcome of the disease correspond to the bacteriological findings, but they do not. The presence of cocci in the cultures does not show that they will play any important part in the disease, and the complications produced by their action—such as pneumonia and nephri tis—seem to be as frequent in cases that give apparently pure cultures of the diphtheria bacillus from the throat as in those that show many cocci as well. When we have to do with a systemic in fection with streptococci as well as the diphtheria bacilli, we speak of the cases as "mixed infections"; but the distinc tion is based upon the clinical symptoms of the disease and not upon the results of the bacteriological examination. We find it most advantageous to divide the cases into mild, severe, or septic, accord ing to the character of the symptoms presented.
Corresponding to these three forms of diphtheria, Monti presents a classification based upon the character of the exudate in the throat:— 1. A fibrinous form in which the diph theritic products are only placed upon the mucous membrane, not incorporated with it. Virchow, Weigert, and Cohn heim call this the croupous form.
2. A mixed form, called also the phlegmonous form, in which the fibri nous exudate lies deep in the tissues as well as upon the mucous membrane.
A septic, or gangrenous, form, in which a fibrinous pseudomembrane is formed in the deep tissues of the mucous membrane, the process really consisting of a necrosis of the tissues and a mingling of the dead particles with the diphthe ritic products.
Similar cla_ssifications are presented by other Continental writers; but we have not yet found it of advantage to attempt to classify our cases by the local appear ances of the throat. Certainly the dis tinctions that Monti makes call for very nice and rather difficnit discriminations.
Symptoms. — These vary sufficiently with the site of the lesions to make it of advantage to consider the local forms separately.