[Drug resistance of Pseudomonas aeruginosa in four community hospitals: influence of antimicrobial use density].

We investigated the relation between hospital antimirobial use density (AUD) and minimum inhibitory concentrations (MIC) for Pseudomonas aeruginosa in four community hospitals. Subjects were a total of 476 strains isolated from urine, sputum, and pus during a total of seven years since 2002, for which 50- and 90-percentile MICs were analyzed. Hospitals A, B, and C moved in 2000, 2005, and 2009, respectively, but MIC50 and MIC90 were stable. MIC values showed significance in five drugs, in which Hospital B showed maximal values in five and Hospital D showed minimal values in four drugs. AUD values were different in nine drugs, Hospital B showing the highest data in meropenem, flomoxef, and sulbactam/cefoperazone while Hospital D having the lowest data in meropenem, ceftazidime, cefotaxime, and sulbactam/cefoperazone. Thus MIC for P aeruginosa may show resistance in the presence of high AUD with wide antimicrobial spectrum.