What are your issues? Pneumococcal animal models have already been performed and I have not read any published issues with regards to this. You can read studies by Iovino et al. (2013 until 2018).

The mice are not getting sick!

Intranasal infection is not very pathogenic. Intratrachael infection can be better. I used D39 strain and did intratrachael infection C57BL/6 with CFUs 10^7. All the mice died within 4 days.

Thank You Ziyi. This is very helpful!