The action of the lytic principle on capsulated bacteria.

Abstract

Since capsulated bacteria, or bacteria in the capsulated state, are known to be more resistant to the action of harmful agents than are organisms without capsules, the question of the resistance of typically capsulated bacteria to the lytic principle is of interest.

The cultures employed in the experiments to be reported were as follows: (1) A laboratory stock strain of the Friedländer pneumo-bacillus; (2) a strain of the same freshly isolated from the root canal of an infected tooth; (3) a laboratory stock strain of B. ozenœ; (4) a laboratory stock strain of B. rhinoscleromatis. The culture medium was a beef infusion broth and beef infusion agar, pH = 7.8. From each of these cultures in the presence of sewage-contaminated river water an active lytic agent was isolated by the usual methods of alternate feeding and filtration.

The maximum dilution of the lytic filtrates which gave inhibition of the homologous culture (one loop in broth) was about the same as in the case of the Shiga dysentery lytic principle, namely, lo^-8. Beyond this, point the titer could not be raised and sometimes it did not attain this degree.

The lytic filtrate developed from the laboratory strain of Friedlander was effective in causing the inhibition and lysis of the strain from the infected tooth, but not against B. ozenæ or B. rhinoscZeronzatis. In a similar manner, the lytic filtrate developed against the tooth strain of Friedlander was active against the laboratory strain but not against the others. The lytic filtrates from B. ozenæ and B. rhinoscZeronzatis were not reciprocal in action; neither did they influence the Friedlander strains.

In the case of all the lytic filtrates acting, in proper dilution, on their homologous strains on agar surfaces, lytic areas were formed.