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Published on: February 21, 2011
Exposure to Cigarette Smoke Enhances Pneumococcal Transmission Among Littermates in an Infant Mouse Model
Daichi Murakami1, Masamitsu Kono1, Denisa Nanushaj1
1Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan.
Insights
Cigarette smoke exposure significantly increases pneumococcal transmission in infant mice. This occurs by enhancing bacterial shedding and increasing susceptibility to colonization, driven by smoke constituents causing inflammation and mucosal damage.
Area of Science:
- Microbiology
- Immunology
- Environmental Health
Background:
- Streptococcus pneumoniae is a common childhood pathogen spread through close contact.
- Environmental factors influencing pneumococcal transmission are not well understood.
- Passive smoking is linked to worse pneumococcal disease outcomes in children.
Purpose of the Study:
- To investigate the impact of cigarette smoke exposure on pneumococcal transmission in an infant mouse model.
- To elucidate the mechanisms by which smoke exposure affects transmission.
Main Methods:
- An infant mouse model was used to study pneumococcal transmission following cigarette smoke exposure.
- Bacterial shedding, colonization susceptibility, and mucosal changes were assessed.
Main Results:
- Cigarette smoke exposure significantly promoted pneumococcal transmission.
- Smoke exposure enhanced bacterial shedding and increased susceptibility to colonization.
- Mechanisms involved local inflammation and mucosal barrier disruption, linked to smoke constituents.
Conclusions:
- Environmental cigarette smoke exposure exacerbates pneumococcal transmission in young children.
- Smoke constituents promote transmission by altering host defenses and mucosal integrity.
- This study provides the first experimental evidence linking environmental factors to pneumococcal transmission dynamics.
Abstract:
Streptococcus pneumoniae, one of the most common commensal pathogens among children, is spread by close contact in daycare centers or within a family. Host innate immune responses and bacterial virulence factors promote pneumococcal transmission. However, investigations into the effects of environmental factors on transmission have been limited. Passive smoking, a great concern for children's health, has been reported to exacerbate pneumococcal diseases. Here, we describe the effect of cigarette smoke exposure on an infant mouse model of pneumococcal transmission. Our findings reveal that the effect of cigarette smoke exposure significantly promotes pneumococcal transmission by enhancing bacterial shedding from the colonized host and by increasing susceptibility to pneumococcal colonization in the new host, both of which are critical steps of transmission. Local inflammation, followed by mucosal changes (such as mucus hypersecretion and disruption of the mucosal barrier), are important underlying mechanisms for promotion of transmission by smoke exposure. These effects were attributable to the constituents of cigarette smoke rather than smoke itself. These findings provide the first experimental evidence of the impact of environmental factors on pneumococcal transmission and the mechanism of pathogenesis.
