Combination antibiotic therapy versus monotherapy for gram-negative bacteraemia: a commentary.

Whether combination antimicrobial therapy is more efficacious than monotherapy for gram-negative bacteraemia remains controversial. Although there are theoretical advantages to combination therapy that are buttressed by in vitro and animal studies, the data from studies of patients with gram-negative bacteraemias have been conflicting. A review of selected clinical studies suggests that combination therapy is associated with improved outcome typically only in severely ill patients and its efficacy may be further limited to those with Pseudomonas aeruginosa, Klebsiella spp. or Enterobacter spp. bacteraemia.