RESEARCH The adult nasopharyngeal

determinant of pneumoco fe s iat as ria the controlled study of pneumococcal carriage episodes in the human nasopharyngeal niche. An episode of pneumo-those under 5 and over 50 years old most at risk. Annu-ally, pneumonia causes an estimated 1.3 million childhood Cremers et al. Microbiome 2014, 2:44 http://www.microbiomejournal.com/content/2/1/44riage in children is the endogenous microbiota present inGenomics, Radboudumc, 6500 HB Nijmegen, The Netherlands Full list of author information is available at the end of the articlecoccal carriage is usually a beneficial immunogenic event [2], but it is also the potential initiation of invasive pneumococcal infections [3]. Pneumococcal carriage is most prevalent in children under 5, ranging from 10 % up deaths worldwide [18]. The burden of IPD may be re-duced by limiting the degree of pneumococcal carriage. Insight into the determinants of pneumococcal carriage will provide better understanding of how interference with this phenomenon could influence its prevalence. Known determinants of pneumococcal carriage are host traits re-lated to exposure and immunity [4,19,20], antibiotic use, and pneumococcal vaccination [12]. An additional elem-ent that appears to be associated with pneumococcal car