Surveillance of bacterial resistance in Peking Union Medical College Hospital during the period from 2005 to 2010

Objective To investigate the antimicrobial resistance of clinical isolates from Peking Union Medical College Hospital (PUMCH) during the period from 2005 to 2010. Methods A total of 26 459 nonduplicate clinical isolates were collected. Disc diifusion test (Kirby-Bauer method) was employed to study the antimicrobial resistance. The data were analyzed by WHONET 5.4 software according to CLSI 2010 breakpoints. Results The top 10 most frequently isolated microorganisms were E. coii (17.7%), P. aeruginosa (10. 5%), S. aurees (10. 3%), A. baumannii (9. 9%), coagulase negative Staphylococcus (9.4%), K. pneumoniae (8%), E. faecales (5%), E. faecium (4.5%), S. maltophilia (3%) and E. cloacae (2.8%). Gram negative organisms and gram positive cocci accounted for 64. 9% and 35. 1 %, respectively. The prevalence of methicillin resistant strains in S. aureus (MRSA) and coagulase negative Staphylococcus (MRCNS) was 52. 8% and 59. 2%, respectively. The resistance rates of MR strains to β-lactams and other antimicrobial agents were much higher than corresponding MS strains. About 76. 4% and 87. 6% of MRSA strains were still susceptible to trimethoprim-sulfamethoxazole and fosfomycin. No staphylococcal strain was resistant to vancomycin, teicoplanin or linezolid. The resistance rate of E. faecalis strains to most of the drugs tested was much lower than those of E. faecium. Several strains of both E. faecium and E. faecalis were found resistant to vancomycin and/or teicoplanin. Most of the vancomycin-resistant strains were van-A type based on their phenotype. No linezolid resistant strain was found. The percentage of β-hemolytic Streptococcus strains susceptible to penicillin was 96. 4%. ESBLs-producing strains accounted for 47. 0%, 27. 2%, 23. 6% and 5. 4% in E. coli, K. pneumoniae, K. oxytoca and P. mirabilis, respectively. The ESBLs-producing strains were always more resistant than the corresponding non-ESBLs-producing strains. A few pan-resistant strains of K. pneumoniae (2. 6%, 13/497)and E. coli (0. 2%, 2/993) were identified in 2010. The percentage of P. aeruginosa strains resistant to imipenem and meropenem was 27. 1% and 20. 9%, respectively. P. aeruginosa isolates showed the lowest resistance rate (13. 2%) to amikacin. And 49. 0% and 66. 6% of A. baumannii strains were resistant to imipenem and meropenem. A. baumannii isolates showed the lowest resistance rates to cefoperazone-sulbactam and minocycline (36. 0% and 14. 2%, respectively). The prevalence of pan-resistant strains in A. baumannii (51. 5%) in 2010 was significantly higher than in 2009 (42. 2%). Conclusions Bacterial resistance is still on the rise, especially MRSA, VRE, MDR and pan-resistant Enterobacteriaceae, P. aeruginosa and A. baumannii strains, which has become a major challenge to medical clinics.