IMMUNOMODULATORY ACTIONS OF ANTIBACTERIAL AGENTS

Although antimicrobial drugs are primarily used to eliminate invading pathogens, there is substantial evidence that they also may alter host homeostasis, particularly the functioning of the immune defence syste m. This 'immunomodulating potential' in fact covers 2 notions: first, eradication of micro-organisms, which are themselves potent exogenous immunomodulators, may make antibacterial agents 'immunorestorers'; sec ondly, by altering bacterial structure and virulence factors, or by di rectly modifying the functions and/or production of cellular and humor al effectors, antibacterial agents may also be considered as 'immunomo dulators'. Only this latter, direct, aspect of the 'non-antimicrobial' effects of antimicrobial drugs will be considered here. Because of et hical considerations, it is generally difficult to assess the clinical relevance of these immunomodulating activities in infectious diseases . However, there is some evidence that the 'non-antibacterial' effects of various antibiotics may be of clinical value, particularly in infl ammatory settings whether or not they are linked to infections. This b rief overview of the clinical relevance of the immunomodulatory effect s of antibacterial agents will focus on 3 main aspects; (i) the conseq uences of intracellular drug uptake on bacterial eradication; (ii) the possible immunostimulatory effect of cefodizime, as an example of imm unorestoration in immunocompromised and infected patients; and (iii) t he anti-inflammatory potential of various antibacterials in inflammato ry settings, whether or not linked to infections.