Interactions among antibiotics, bacteria and the human immune system: the clinical relevance of in vitro testing.

The role of interactions of the host immune system with antibacterial activities of antibiotics is extremely complex and its analysis is still at an early stage. Standard in vitro trests of antibiotic susceptibilities of pathogens provide only limited information since they do not take into account either the potential interaction of immunomodulating activities of antibiotics in vivo or the participation of the host immune response in the infection outcome. The understanding of these complex relationships is of major importance in treating immunocompromised patients, but this approach is still under investigation and much work remains to be done in order to confer more significance on in vitro testing.