Apart from their direct antimicrobial activity, some antimicrobial age
nts may interfere in the complex host-microorganism interplay by modul
ating the natural response to invading pathogens. The three main aspec
ts of this non-antibiotic effect (alteration of bacterial virulence, s
ynergism with/impairment of the natural host response, impact on effec
tor cell progenitors) will be briefly reviewed here, along with their
potential incidence in the clinical outcome of infectious diseases.