The role of clonality in the global spread of fluoroquinolone-resistant bacteria.

The molecular epidemiology of fluoroquinolone resistance in a number of bacterial pathogens suggests that the persistence and spread of resistance is associated with a small number of highly successful bacterial clones. The recent description of fluoroquinolone-resistant strains among global clones of pneumococci raises the likelihood that the percentage of pneumococci resistant to fluoroquinolones will increase as this class of agent is increasingly used for the management of respiratory tract infection in adults. Although these clones remain fluoroquinolone susceptible in children, their widespread distribution argues against the extension of fluoroquinolone use to the management of respiratory tract infection in children.