Effect of Tannic Acid on Intranasal Infection with Pneumococci

Abstract

It has been shown 1 , 2 that certain viruses are infective for mice when instilled into the nares and that this capacity to invade the body of the mouse through the mucosa of the nose can be greatly diminished by preliminary intranasal treatments with tannic acid or alum-solutions. It has also been shown 3 that certain strains of pneumococci are infective for mice by the nasal route and that, under the conditions of the experiment, invasion takes place both through the nasal mucosa and through the pulmonary alveolar walls. 4

The present experiments were planned to test whether this nasal infectivity of pneumococcus strains is modified by preliminary tannic-acid treatments. For this purpose, 5 experiments were undertaken using groups of young (3 to 6 weeks old) Swiss mice. In each experiment 15 mice were treated with weak solutions of tannic acid for 3 or 4 days before the infecting inoculation was made. In 2 cases, 0.7 or 1.0% solution of tannic acid in normal saline was used and in the other 3, 0.8% solutions of tannic acid in 1.0% glycerol. In the first test, 7 preliminary treatments, each of 0.03 cc. of the tannic acid, were given intranasally; in the second, 9, in the third, 6, and in the last 2, 8 similar treatments. Fifteen mice remained untreated as controls in each test.

Cultures of strains of pneumococci of both Type III and Type XIX, known to be intranasally virulent, were used. In the past the use of intranasally virulent strains of pneumococci has been attended with the difficulty that this virulence or invasiveness, which is independent of the intraäbdominal virulence is apt to be lost suddenly and without apparent reason during subculture or on animal passage 3 and cannot be regained by any of the means so far adopted.