Remarks upon the pneumotoxin / by Allan MacFadyen, M.D. (from the Bacteriological Department, King's College.).

  • Macfayden, Allan, 1860-1907
Date:
[1906?]
Catalogue details

Licence: In copyright

Credit: Remarks upon the pneumotoxin / by Allan MacFadyen, M.D. (from the Bacteriological Department, King's College.). Source: Wellcome Collection.

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    * > of the existence of a genuine secreted toxin. There can be little doubt that the essential pneumotoxin is of the endo- cellular type, and that it is this toxin contained within the body of the organism which is to be regarded as the more important factor in the possible production of any antitoxic immunity. As few direct experiments have been made in this important direction, it may be of interest to put on record the results I have so far obtained. The object of the experiments was, in the first instance, to extract a toxin from the bodies of the pneumococci by means of the cold grinding method successfully employed in the case of typhoid, cholera, and other organisms.10 The pneumococci were isolated from the human subject, and their virulence raised by passages through the rabbit. The cultures were made directly from rabbits which had died of a pneumococcic septicaemia. The heart’s blood of the animals was spread over the surface of nutrient agar in Roux bottles. This procedure favoured a rapid and good growth of the pneumococcus, the cultures after two to three days’ incubation at blood heat furnishing ample material for each experiment. The resultant mass, after trituration of the cocci, was taken up in 1 in 1,000 caustic potash solution, then spun and filtered. If care is taken to use pneumococci of marked virulence for grinding, acutely toxic filtrates of their cell juices are readily obtained. The strains in which a loss of virulence had occurred did not yield cell juices of any marked toxicity; for example, 1 c.cm. on intravenous, and i c.cm. on intra¬ cerebral injection did not affect rabbits, nor did 1 c.cm., fc.cm., and i c.cm. kill guinea-pigs or mice on intra- peritoneal injection; on the other hand, the filtered cell juices from virulent strains killed acutely in the above doses. The parallelism between virulence and toxicity was unmistakable, and is further illustrated in the figures given below. It was found that by regarding this point one was in a position to obtain not only constantly toxic cell juices from the pneumococcus, but also to increase the toxicity by further exaltation of the virulence of the organism. The toxicity of the filtered cell juices was tested on rabbits, guinea-pigs, and. mice, the majority of the experi¬ ments being made on the guinea-pig. The following figures illustrate the results obtained after three to eight passages of the pneumococcus through the rabbit. A.—Filtered Cell Juices of the Pneumococcus Directly Isolated from the Rabbit. Rabbit.—1.0 c.cm. intravenous. Acute diarrhoea and death. ,, 0.5 ,, ,, No effect. ,, 0.2 ,, intracerebral. Dead. Guinea-pig.—2.0 c.cm. intraperitoneal. Dead. j> 1*0 >> n y> it 0-5 ,, i, Mouse.—0.1 c.cm. intraperitoneal. Dead. ii 0 5,, ,, ,,
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