POPULATION DYNAMICS OF BACTERIAL PATHOGENS

Human bacterial pathogens reflect the great diversity of the prokaryotic world, and it is intriguing that there are examples of genetically unrelated bacteria that have adopted similar ways of exploiting humans as an ecological niche. The population dynamics of obligate bacterial pathogens and commensals in humans are greatly influenced by the mechanisms by which the bacteria spread among hosts as, to persist in a given host population, such organisms must transmit effectively. Populations of certain bacterial pathogens are genetically highly diverse (e.g., Neisseria meningitidis and the enteric pathogen Campylobacter jejuni), while others, such as M. tuberculosis and Bordetella pertussis, are remarkably uniform. Population diversity is represented, at least to some degree, in the collections of pure cultures that are available for many bacterial pathogens, some of which span many decades and large geographical areas. The chapter focuses on models on bacterial population structure. Despite recent advances, however, there remains a paucity of the parametric descriptions of bacterial population structure, evolution, and epidemiology that are necessary to make the robust predictions required for both fundamental research and the design and implementation of intervention strategies. It is in these areas where the next developments in the analysis of bacterial pathogen populations are most urgently needed, and, as many of the tools for this work are now available, the prospects of developments in this area are especially exciting.