Epidemiology and pathogenesis of Moraxella catarrhalis colonization and infection

Moraxella catarrhalis is part of the normal bacterial flora in the nasopharynx of children,\nalthough over the past two decades, it has emerged as a significant bacterial pathogen\nand not simply a commensal colonizer. The bacterium rapidly colonizes the nasopharynx\nsoon after birth and many factors affect nasopharyngeal carriage of this human-specific\npathogen, including for example, the presence of siblings, day-care attendance and respiratory\nillness. Otitis media (OM) is a particularly important respiratory illness during\nearly childhood and the primary reason for children to visit a physician. The most common\nbacterial species cultured from the nasopharynx of children during OM episodes\nare Streptococcus pneumoniae, Haemophilus influenzae and M. catarrhalis, either as\nsingle pathogens or as co-cultures, with the patterns of nasopharyngeal colonization\nby microorganisms being important determinants for OM disease. There is increasing\ninformation regarding the biological mechanisms facilitating M. catarrhalis-mediated\ncolonization and disease development, with most publications stressing the importance\nof bacterial adherence as an essential step in this process.