Abstract
A review of the literature on Bact. melaninogenicum 1-4 reveals an uncertainty as to its pathogenicity and as to the existence of more than one serological type. Evidence is here presented that the proteins extracted from 2 strains of this organism are different in their chemical and antigenic properties and that pathogenicity can be demonstrated under certain conditions.
Two strains were studied: The first (py) was isolated from the gums of a patient suffering from pyorrhoea and the second (M19), from the lung of a monkey which had developed a pulmonary abscess after intrabronchial inoculation with infectious material. 5 Both cultures conformed to the description given by Shevky, Kohl and Marshall 3 and Burdon. 1 , 2 The first strain differed, however, from the second in its failure to liquefy gelatin and to form indol in peptone-water.
The pathogenicity of pure cultures was tested by injecting dogs intrabronchially, white mice subcutaneously and rabbits intracutaneously.
With the aid of a fluoroscope, 2 dogs were injected intrabronchially with large doses of Bad. melaninogenicum suspended in a menstruum of starch. 6 One animal developed a febrile reaction. A rcentgenogram of the lung showed an area of increased density of the infected lobe.† The other had increased bronchial markings which lasted for at least a month.
Mice were inoculated subcutaneously in the groin with 0.05 to 0.1 cc. of broth culture of Bact. melaninogenicum. Edema and inflammation developed which persisted for 24 hours. Control animals, injected with heat-killed cultures, showed no demonstrable lesions.
Rabbits were injected intracutaneously with 0.02 cc. of staphylococcal toxin combined with 1/5 unit of Squibbs antitoxin; 48 hours later these sites were inoculated with living or heat-killed cultures of Bact. melaninogenicum. Inflammation, exudation and necrosis were observed only in areas infected with living cultures.
Experiments were conducted by the method of Tillett and Garner, 7 employing alcohol for precipitation and concentration and human fibrinogen and thrombin for the demonstration of fibrinoly-sin. Strain (M19) gave complete lysis in a 1:4 dilution after 40 minutes'incubation, while strain (py) showed partial (2+) lysis only in original concentrations.δ The presence of fibrinolysin is considered by many authors as evidence of invasiveness or pathogenicity. 8-9
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