Limitations of current antimicrobial therapy in the immunosuppressed host: looking at both sides of the coin.

During the last twenty years there have been considerable advances in the antimicrobial management of the immunosuppressed host. These include the development of antibiotics with broad-spectrum and high bactericidal activity along with the appreciation of the importance of promptly initiating empiric antibiotic therapy when the granulocytopenic patient becomes febrile and continuing them (in some cases with empiric antifungal therapy) until the resolution of granulocytopenia. Nonetheless, infection still remains a major cause of death in compromised hosts and a number of limitations of therapy persist. Included are a limited repertoire of drugs active against fungi (particularly Aspergillus) as well as certain viruses (for example, cytomegalovirus) and the inability to eradicate certain sites of infection (for example, Pseudomonas pneumonia) even with effective agents. Current investigations are focused on developing new antimicrobial agents as well as methods to improve the altered host defenses of immunosuppressed patients, both as adjuvants to therapy and, eventually, as a means to prevent infectious complications.