Infect Immun. 2016 Jan 19. pii: IAI.01275-15. [Epub ahead of print]

Streptococcus pneumoniae colonization disrupts the microbial community within the upper respiratory tract of aging mice.

Thevaranjan N1, Whelan FJ2, Puchta A1, Ashu E1, Rossi L3, Surette MG4, Bowdish DM5.

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Nasopharyngeal colonization by the Gram-positive bacterium, Streptococcus pneumoniae, is a pre-requisite for pneumonia and invasive pneumococcal diseases. Colonization is asymptomatic, involving dynamic and complex interplay between commensals, the host immune system and environmental factors. The elderly are at an increased risk of developing pneumonia, which might be due to changes in the respiratory microbiota that would impact bacterial colonization and persistence within this niche. We hypothesized that the composition of the upper respiratory tract (URT) microbiota changes with age and can subsequently contribute to sustained colonization and inefficient clearance of S. pneumoniae. To test this, we used a mouse model of pneumococcal colonization to compare the composition of the URT microbiota in young, mid-age and old mice in the naïve state and during the course of colonization using nasal pharyngeal washes. Sequencing of the variable region 3 (V3) of the 16S rRNA gene was used to identify changes occurring with age and throughout the course of S. pneumoniae colonization. We discovered that age affects the composition of the URT microbiota and that colonization with S. pneumoniae is more disruptive of pre-existing communities in older mice. We have further shown that host-pathogen interactions following S. pneumoniae colonization can impact the populations of resident microbes, including Staphylococcus and Haemophilus. Together, alterations to the URT microbiota could be detrimental to the elderly, resulting in increased colonization of S. pneumoniae and decreased efficiency in its clearance.

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PMID: 26787714 [PubMed - as supplied by publisher]