In vitro considerations in monotherapy and combination therapy for severe infections.

The introduction of the many new penicillins and cephalosporins has not radically altered the results of therapy in infected patients with impaired host defenses. Pseudomonas-active beta-lactam combinations with aminoglycosides remain the mainstay of treatment. Among the new cephalosporins, only ceftazidime shows promise in clinical trial, and the results of the fourth European Organization for Research on Treatment of Cancer (EORTC) trial, which includes the combination of amikacin plus ceftazidime, are awaited with interest. Whichever regimen is chosen, care must be taken to detect the emergence of resistant strains. This may entail changing the empiric regimen used on a cyclic basis in order to minimize the problem and maintain an acceptable level of clinical response.