Canadian survey of antimicrobial resistance in Klebsiella spp. and Enterobacter spp. The Canadian Antimicrobial Resistance Study Group.

Increasing antimicrobial resistance has been reported for Klebsiella spp. and Enterobacter spp. The in-vitro activities of 14 antimicrobial agents against 656 clinical isolates of Klebsiella spp. and 630 isolates of Enterobacter spp. collected from seven cities in Canada were determined by microbroth dilution. There was no regional variation in the susceptibility patterns. Klebsiella spp. remain highly susceptible to most antimicrobials, only one isolate was resistant to third-generation cephalosporins. However, many isolates of Enterobacter spp. (> 16%) were resistant to the third-generation cephalosporins with marked cross-resistance to piperacillin (63.1%), piperacillin/tazobactam (44.9%), and aztreonam (76.6%). Gentamicin, tobramycin, imipenem, ciprofloxacin, cefepime, and cefpirome were consistently active against most isolates of Enterobacter spp. including those resistant to the third-generation cephalosporins.