Objective: To investigate the antimicrobial resistance among the nosocomial gram-negative pathogens from 15 teaching hospitals located in different areas in China in 2005.
Methods: A total of 1927 non-repetitive nosocomial gram-negative pathogens were collected from 15 teaching hospitals in different areas in China and sent to the central lab for reidentification and susceptibility testing. The levels of minimal inhibitory concentration (MIC) of 18 antimicrobial agents were determined by agar dilution method. WHONET 5.4 software was used to analyze the data.
Results: The strains of Escherichia coli, Klebsiella pneumoniae, and Proteous mirabilis isolates that did not produce extended spectrum beta lactamases (ESBLs) showed high sensitivity to beta-lactams. The antibiotics with a susceptibility rates over 80% against the strains of Entorobacter cloacae, Enterobacter aerogene, Citrobacter spp, Serratia spp, and Proteous vulgaris producing AmpC enzyme included meropenem, imipenem, and piperacillin-tazobactam, and these 3 drugs showed a susceptibility rate of more than 80% against the ESBL-producing strains of Escherichia coli and Klebsiella pneumoniae. Other antimicrobial agents showing a relatively high activity against Enterobacter spp, Citrobacter spp, Serratia spp and Proteous vulgaris included cefepime (67.3% - 100%), amikacin (67.3% - 95.2%), ceftazidime (52.9% - 100%) and cefoperazone-sulbactam (51.9% - 100%). The susceptibility rate of fluoroquinolones was 34.8% - 36.1% against non-ESBL-producing Escherichia coli and was 13.4% - 17.1% against ESBL-producing isolates. The most active agent against Pseudomonas aeruginosa was polymyxin B (95.6%). The agents with the activity rates of 70% - 80% included meropenem, imipenem, amikacin, and piperacillin-tazobactam. The antibiotic with a high susceptible rate against Acinetobacter baumannii was polymyxin B (98.3%), followed by imipenem (80.8%), meropenem (76.2%), and minocycline (67.4%). The susceptible rates of other agents were all below 60%. The agents with relatively high activity against Stenotrophomonas maltophilia included minocycline (85%), levofloxacin (82.5%), and trimethoprim-sulfamethoxazole (77.5%). The agents with a relatively high activity against Burkholderia cepacia included minocycline (77.2%) and meropenem (61.4%).
Conclusion: Carbapenem, piperacillin-tazobactam, amikacin and cefepime remained relatively high activity against nosocomial Enterobacteriaceae, Non-fermenting pathogens have lower susceptibility to the antimicrobial agents than before.