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

Zafar MA, Wang Y, Hamaguchi S, Weiser JN.

Cell Host & Microbe. (2017) 21, 73-83

Speaker: An-Chi Gu (顧安琪)                                              Time: 14:00~15:00, Jun. 7, 2017

Commentator: Jenn-Wei Chen, Ph.D. (陳振暐老師)           Place: Room 601

Abstract:

The mucosal surfaces of the airways are colonized by a complex and extensive flora (1). These microbes must overcome two fundamental challenges. First one is limited nutrients and the second is how to increase transmission. Host-to-host transmission is a critical step for infection, however, there is currently minimal understanding of either microbial or host factors involved in host-to-host transmission. For the opportunistic pathogen of the human respiratory tract, Streptococcus pneumonia, transmission is more common in the setting of influenza virus infection because of the inflammation triggerd by virus (2)(3). Several factors are contributed to the host inflammation to the pneumococcus like pneumolysin, a pore-forming cytotoxin and major virulence determinant. In this study, the authors used infant mouse model to examine the requirements for host-to-host transmission of Streptococcus pneumoniae. They showed that upper respiratory tract inflammation induced by pneumococcal colonization, particularly in response to pneumolysin, promoted bacterial shedding to allow transmission between hosts. Pneumolysin also enhanced bacterial survival outside of the host. Moreover, direct contact between infant mouses was not required for transmission indicating the importance of environmental reservoirs. These findings provide evidence of a microbial strategy for transit to new hosts and indicate that the benefit to the organism of a higher rate of transmission compensates for the non-beneficial within-host effects of the toxin.

References:

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