Influence of bacterial interactions on pneumococcal colonization of the nasopharynx

► Streptococcus pneumoniae is a member of a complex microbial community in the nasopharynx. ► Co-colonization with ≥2 strains is common, facilitating recombination and affecting density. ► Interactions with other nasopharyngeal bacteria influence carriage prevalence and virulence. ► Interspecies quorum-sensing may regulate nasopharyngeal bacterial biofilm formation.