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.