Specific Soluble Substance of Pneumococcus in Lungs of Dogs Recovered from Experimental Lobar Pneumonia

Abstract

That the soluble specific substance of the pneumococcus may remain in tissues infected with this organism even after the inflammatory exudate has disappeared was first suggested by the studies of Dochez and Avery 1 on the excretion of “S” substance in the urine of cases of lobar pneumonia in human beings. They found that the soluble specific substance was excreted in some cases for days or weeks after recovery from the disease. In some instances this continued excretion of “S” could be correlated with delayed resolution, but in other cases this was not the explanation. It would seem probable that in these latter instances “S” remained stored in the pulmonary tissues for some time after the other constituents of the inflammatory exudate had apparently disappeared.

A direct approach to this problem cannot be made in human beings because of obvious difficulties. However, the availability of an experimental animal in which a pneumococcus pneumonia may be induced makes possible the determination of “S” substance in the lungs at various intervals after recovery. The present report is a record of preliminary studies of the persistence of “S” substance in the lungs of dogs recovered from experimental lobar pneumonia.

Healthy adult male dogs were infected with Type I pneumococci by the method of Terrell, Robertson, and Coggeshall. 2 Some of these dogs had been previously “Vaccinated” by spraying formalized Type I pneumococci into the bronchial tree. Two dogs in the group had been similarly treated with a 0.9% salt solution as controls. The “vaccination” procedure had been carried out in the course of a separate experiment but the dogs after recovery were utilized for this study. The other animals in the series had received no preliminary treatment.