Antimicrobial resistance surveillance among pathogens causing nosocomial bloodstream infection, pneumoniae and intra-abdominal infection at 14 teaching hospitals in China

Abstract

Objective To investigate the distribution and antimicrobial resistance among nosocomial pathogens from 14 teaching hospitals located in different areas in China from October 2006 to October 2007. Methods According to the study protocol, non-repetitive pathogens from nosocomial bloodstream infection (BSI), pneumoniae (HAP) and intra-abdominal infection (IAI) were collected and sent to the central laboratory for reidentification and susceptibility testing. The minimal inhibitory concentrations (MICs) of 29 antimicrobial agents were determined by agar dilution method. WHONET5. 4 software was used to analyze the data. Results A total of 2 660 clinical isolates were collected. The top three pathogens of BSI included Escherichia coli ( 30. 0% ), Klebsiella pneumoniae ( 12. 0% ) , and Staphylococcus aureus (11. 2% ). The top three causing pathogens of HAP were Pseudomonas aeruginosa (23. 4% ) , Acinetobacter baumannii{ 17. 4% ) , and Klebsiella pneumoniae ( 13. 8% ). The top three causing pathogens of IAI were Escherichia coli ( 38. 8% ) , Klebsiella pneumoniae ( 10. 2% ) and Pseudomonas aeruginosa ( 9. 2% ) . For Escherichia coli and Klebsiella spp. isolates, the antimicrobial agents with higher than 80% susceptibility rate included tigecycline (100% ) , meropenem (99. 3% -100% ) , imipenem (98. 5% -100% ), and piperacillin/ tazobactam ( 83. 8%-95. 1%) . The susceptibility rates of fluoroquinolones were 12.4%-44. 9%. For Enterobacter spp. , Citrobacter spp. and Serratia spp. , the susceptibility rates of tigecycline were 99. 2% -100% and the value of imipenem and meropenem were 96. 6% -100%. Other antimicrobial agents which showed relatively higher activity included amikacin ( 82. 8% -96. 6% ) , piperacillin/tazobactam ( 73. 4% -93. 1% ) , cefepime ( 69. 0% -82. 8% ) and cefoperazone/sulbactam ( 72. 6% -75. 9% ) . The susceptibility rates of fluoroquinolones against these species were 55. 2% -82. 8% . The prevalence of multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii was 18. 7% , 54. 0% , respectively. Polymyxin B showed the highest susceptibility rate against Pseudomonas aeruginosa(93. 5% ), followed by amikacin and piperacillin/tazobactam (75. 1%) . Polymyxin B also showed the highest susceptibility rate against Acinetobacter baumannii ( 96. 2% ), followed by tigecycline (92.1%), imipenem ( 59. 4% ), minocycline (59.4%), and meropenem ( 56.5% ) . The prevalence of methicillin-resistant Staphylococcus aureus ( MRSA) and coagulase-negative Staphylococci was 64. 5% , and 82. 8% , respectively. All Staphylococci isolates were susceptible to tigecycline, vancomycin and teicoplanin. Nine vancomycin-resistant enterococci (VRE) strains were identified, and the VRE rate was 4.3%. Conclusions Tigecycline, carbapenems, piperacillin/tazobactam, amikacin and cefepime remained relatively high activity against nosocomial Enterobacteriaceae, Polymyxin B showed the highest activity against Pseudomonas aeruginosa and Acinetobacter baumannii. The susceptibility rate of tigecycline against Acinetobacter baumannii was 92. 1%. Tigecycline, vancomycin and teicoplanin remained high activity against nosocomial gram-positive cocci. Key words: Bacteremia;  Enterobacteriaceae;  Pseudomonas aeruginosa;  Acinetobacter;  Drug resistance; bacterial;  Microbial sensitivity tests