Intra-Species Interactions in Streptococcus pneumoniae Biofilms

Abstract

Streptococcus pneumoniae is a human pathogen responsible for high morbidity and mortality worldwide. Disease is incidental and is preceded by asymptomatic nasopharyngeal colonization in the form of biofilms. Simultaneous colonization by multiple pneumococcal strains is frequent but remains poorly characterized. Previous studies, using mostly laboratory strains, showed that pneumococcal strains can reciprocally affect each other’s colonization ability. Here, we aimed at developing a strategy to investigate pneumococcal intra-species interactions occurring in biofilms. A 72h abiotic biofilm model mimicking long-term colonization was applied to study eight pneumococcal strains encompassing 6 capsular types and 7 multilocus sequence types. Strains were labeled with GFP or RFP, generating two fluorescent variants for each. Intra-species interactions were evaluated in dual-strain biofilms (1:1 ratio) using flow cytometry. Confocal microscopy was used to image representative biofilms. Twenty-eight dual-strain combinations were tested. Interactions of commensalism, competition, amensalism and neutralism were identified. The outcome of an interaction was independent of the capsular and sequence type of the strains involved. Confocal imaging of biofilms confirmed the positive, negative and neutral effects that pneumococci can exert on each other. In conclusion, we developed an experimental approach that successfully discriminates pneumococcal strains growing in mixed biofilms, which enables the identification of intra-species interactions. Several types of interactions occur among pneumococci. These observations are a starting point to study the mechanisms underlying those interactions.

Dissemination of Tn 916 -Related Integrative and Conjugative Elements in Streptococcus pneumoniae Occurs by Transformation and Homologous Recombination in Nasopharyngeal Biofilms

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Development and validation of a multiplex real-time PCR assay for detection and quantification of Streptococcus pneumoniae in pediatric respiratory samples

“…Accurate and reliable Spn detection is essential for appropriate disease management in lower respiratory sources and for understanding colonization dynamics in upper respiratory sources. Despite this need, traditional Spn microbiological methods (primarily culture and antigen testing), as well as current PCR methods, lack sensitivity and specificity due to both high genetic diversity within and between Spn strains and characteristic phenotypic and genotypic Spn elements in non- Spn species ( 9 , 12 , 15 , 20 ). To address this need, we developed and validated a quantitative real-time PCR targeting three Spn genomic regions for improved sensitivity and specificity for detecting Spn in respiratory specimens.…”

The Role of Pyroptosis and Autophagy in the Nervous System

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