Antibiotic Susceptibilities of Pseudomonas aeruginosa Isolated from Blood Samples and Antibiotic Utilization in a University Hospital in Japan

Introduction Pseudomonas aeruginosa is one of the most important causes of nosocomial infection. Several reports indicated a correlation of antimicrobial usages and declined susceptibilities. In this report, we evaluated their relation in a tertiary care teaching hospital in Tokyo, Japan for 4 years. Methods We evaluated the susceptibilities of 149 strains of P. aeruginosa isolated from blood samples and consumption of anti-pseudomonal antibiotics as antimicrobial use density from 2009 to 2012 in the University of Tokyo Hospital in Tokyo, Japan. Results Usages of carbapenems and anti-pseudomonal cephalosporins decreased 44% and 31% from 2009 to 2011, and then increased 30% and 24% in 2012, respectively. Usage of piperacillin–tazobactam increased 87% from 2009 to 2012, which was introduced in the hospital in 2008. Consumption of fluoroquinolones and aminoglycoside remained low in those years. Susceptibilities to cephalosporins, carbapenems (except for panipenem–betamipron), penicillins, and fluoroquinolones declined between 22% and 39% in 2010, increased in the range of 16–31% in 2011, and increased by 1–14% in 2012. Susceptibility of panipenem–betamipron ranged between 25% and 32%. Susceptibility to aminoglycoside was more than 90% during this period. No relationship between antimicrobial usages and susceptibilities of P. aeruginosa was observed. Conclusion Susceptibilities of P. aeruginosa did not correlate with the usage of antibiotics in our hospital. Several infection control measures and other factors might contribute to changing the susceptibilities of bacteria.