Susceptibilities of 4,080 bacterial strains of clinical isolates to tazobactam/piperacillin and other antimicrobial agents as of 2010

Surveillance of β-lactamase production and susceptibilities to antimicrobial agents including tazobactam/piperacillin(TAZ/PIPC) in 4,080 bacterial strains isolated in 2010 were conducted in Japan. β-Lactamase production was investigated over 90% of the strains of Moraxella catarrhalis, Escherichia coli, Citrobacter spp., Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens, indole-positive Proteus spp., Pseudomonas aeruginosa, Acinetobacter spp. and Bacteroides fragilis group., about 60% of staphylococci and 11.1% of Haemophilus influenzae. An increase of the β-lactamase producers in H. influenzae strains was noted, when compared with previous investigations conducted between 2001 and 2006. Extended spectrum β-lactamase(ESBLs) producing strains in E. coli, K. pneumoniae and P. mirabilis were 17.8%, 3.9% and 12.8%, respectively. Increasing levels of ESBLs producers in E. coli, K. pneumoniae and P. mirabilis were investigated compared with previous investigations. Metallo β-lactamase producers in E. cloacae, P. aeruginosa and Acinetobacter spp. were 2.5%, 1.0% and 3.3%, respectively, and no strain of S. marcescens was detected. Susceptibility of 4,080 strains to TAZ/PIPC based on the criteria of the Clinical and Laboratory Standards Institute were distributed from 80.9% in P. aeruginosa to 100% in methicillin-susceptible S. aureus and coagulase-negative staphylococci, P. mirabilis, Proteus spp. (except for Proteus mirabilis) and H. influenzae including β-lactamase-negative ampicillin-resistant H. influenzae. When compared with those in previous investigations, susceptibility to TAZ/PIPC in this decade was not changed and some species of Enterobacteriaceae tend to be susceptible. From these results, TAZ/PIPC is considered as a useful initial therapeutic antimicrobial agent for the infectious diseases reported in various therapeutic guidelines.