High frequency of antibiotic resistance among Gram-negative isolates in intensive care units at 10 Swedish hospitals

Objective To investigate the resistance rates among Gram-negative isolates in Swedish intensive care units (ICUs). Methods During 1994–95, members of the Swedish Study Group collected, on clinical indication, 502 consecutive initial isolates of Gram-negative bacteria from patients admitted to ICUs at 10 Swedish hospitals and performed minimal inhibitory concentration (MIC) determinations with the Etest. Breakpoints were defined according to the criteria of the Swedish Reference Group for Antibiotics (SRGA). Results The distribution of bacterial species was: Escherichia coli Klebsiella spp. > Enterobacter spp. > Pseudomonas aeruginosa > Haemophilus spp. > Proteus spp. > Stenotrophomonas maltophilia > Citrobacter spp. > Acinetobacter > Pseudomonas spp. > Morganella morganii > Serratia spp. Together these constituted 97% of all isolates. The frequencies of resistance for all the initial Gram-negative isolates were: ceftazidime 6.8%, cefotaxime 14.9%, ceftriaxone 18.5%, cefuroxime 44.1%, ciprofloxacin 4.2%, co-trimoxazole 17.8%, gentamicin 5.8%, imipenem 8.6%, piperacillin 20.2%, piperacillin/tazobactam 12.9% and tobramycin 5.8%. Conclusions Among Gram-negative isolates in Swedish ICUs, a very high frequency of resistance was seen to cefuroxime, and rather high frequencies of resistance to cefotaxime, ceftriaxone, piperacillin and piperacillin/tazobactam. These drugs cannot be recommended for further use as empirical monotherapy for severe ICU-acquired Gram-negative infections in ICUs in Sweden.