Host-to-Host Transmission of Streptococcus pneumoniae Is Driven by Its Inflammatory Toxin, Pneumolysin

Publication date: 11 January 2017
Source:Cell Host & Microbe, Volume 21, Issue 1
Author(s): M. Ammar Zafar, Yang Wang, Shigeto Hamaguchi, Jeffrey N. Weiser
Host-to-host transmission is a critical step for infection. Here we studied transmission of the opportunistic pathogen Streptococcus pneumoniae in an infant mouse model. Transmission from nasally colonized pups required high levels of bacterial shedding in nasal secretions and was temporally correlated with, and dependent upon, the acute inflammatory response. Pneumolysin, a pore-forming cytotoxin and major virulence determinant, was both necessary and sufficient to promote inflammation, which increased shedding and allowed for intralitter transmission. Direct contact between pups was not required for transmission indicating the importance of an environmental reservoir. An additional in vivo effect of pneumolysin was to enhance bacterial survival outside of the host. Our findings provide experimental evidence of a microbial strategy for transit to new hosts and explain why an organism expresses a toxin that damages the host upon which it depends.

Graphical abstract

Teaser

The requirements for host-to-host transmission of the leading respiratory pathogen Streptococcus pneumoniae were examined in an infant mouse model. Shedding of colonizing bacteria by the donor animal is increased by inflammation. The bacterial toxin pneumolysin promotes inflammation, increases bacterial survival after exit from the host, and is required for transmission.


http://ift.tt/2jEZv0C