[Combination therapy against multidrug-resistant bacteria].

The purpose of antibiotic combination therapy includes two points, as follows; 1) expectation of synergistic effects, 2) preventing the emergence of drug-resistant bacteria following exposure to antibiotics. Synergism has been shown in vitro for many antibiotic combinations and bacterial species, but it is uncertain whether synergistic effects in vitro are applicable to the clinical setting and lead to a better prognosis. beta-lactam and aminoglycoside combinations have synergistic effects against Gram-negative bacteria, including Pseudomonas aeruginosa, Klebsiella, Escherichia coli, and other Enterobacteriaceae in vitro; however, combination therapy is not considered for these pathogens routinely in vivo. Multidrug-resistant (MDR) pathogens have emerged as increasingly problematic causes of hospital-acquired infection. When MDR Gram-negative bacillary infection occurs in immunocompromised patients, combination therapy is considered. In Japan, MDR P. aeruginosa is becoming a serious problem in the clinical setting. Here, we present an antibiotic combination therapeutic strategy against MDR P. aeruginosa infection.