Evaluation of antimicrobial susceptibility for β-lactams against clinical isolates from 51 medical centers in Japan (2008).

This antimicrobial resistance surveillance study was performed in 51 medical centers in Japan over an 11-year period. The susceptibilities of 4228 strains including Escherichia coli (491 strains), Klebsiella spp. (462 strains), Enterobacter spp. (459 strains), Citrobacter freundii (358 strains), indole-positive Proteus spp. (386 strains), Serratia spp. (443 strains), Acinetobacter spp. (327 strains), Pseudomonas aeruginosa (473 strains), oxacillin-susceptible Staphylococcus aureus (481 strains), and coagulase-negative staphylococci (CoNS; 348 strains) were tested with 7 β-lactams (cefepime, cefpirome, ceftazidime, cefoperazone/sulbactam, imipenem, and piperacillin for gram-negative bacteria, or oxacillin for gram-positive bacteria). No resistance to these β-lactams (with the exception of ceftazidime) was found in oxacillin-susceptible S. aureus and CoNS. Of the E. coli clinical isolates, 24.6% were resistant to piperacillin, whereas 3.5% or less (cefpirome = 4.5%) were resistant to other β-lactam agents. Klebsiella spp. isolates were more susceptible to imipenem (99.6%), cefepime (98.7%), ceftazidime (98.5%), cefpirome (97.6%), and cefoperazone/sulbactam (97.6%). Isolates of Enterobacter spp., C. freundii, and Serratia spp. were susceptible to imipenem, cefepime, and cefpirome as well. The sensitivities of these organisms against cefepime and cefoperazone/sulbactam were 100%. Acinetobacter spp. isolates were less resistant to cefoperazone/sulbactam (0.6% resistance), imipenem (0.9%), and ceftazidime (2.8%) compared with other β-lactam antibiotics tested. Isolates of P. aeruginosa were more susceptible to piperacillin (9.1% resistance), cefoperazone/sulbactam (9.5%), and cefepime (6.6%) compared with ceftazidime (10.8%), cefpirome (16.3%), and imipenem (23.5%). The proportion of strains resistant to β-lactam antimicrobials has decreased compared with data from 2006 (Diagn. Microbiol. Infect. Dis. 60:177-183), reflecting the reduced consumption of β-lactams in Japan.