Novel antibiotic combinations against infections with almost completely resistant Pseudomonas aeruginosa and Acinetobacter species

For infections with antibiotic-susceptible strains of Pseudomonas aeruginosa, most studies have suggested that combination therapy, usually with a beta-lactam antibiotic plus an aminoglycoside, is preferable for patients with bacteremia and neutropenia. Against infections with Pseudomonas aeruginosa or Acinetobacter baumannii isolates that are resistant to all antibiotics except the polymyxins, several novel antibiotic combinations demonstrate increased activity in vitro compared with that of any single agent. Whether these combinations yield outcomes that are improved over those seen with a polymyxin or other agent alone remains to be determined. However, against infections with species resistant to all antibiotics, including polymyxins, novel combinations are the only remaining therapeutic option.