Surveillance of antimicrobial resistance in clinical isolates from Taiping People′s Hospital in Dongguan during 2011

Objective To investigate the resistance of clinical isolates to antimicrobial agents commonly used in Taiping People′s Hospital,Dongguan during 2011.Methods ATB STREP 5 was used for susceptibility testing of Streptococcus pneumoniae,ATB HAEMO for Haemophilus influenzae and Moraxella catarrhalis.Disk diffusion susceptibility test was used to determine the antimicrobial susceptibility of other bacteria.The data were analyzed by WHONET 5.5 software according to CLSI 2010 breakpoints.Results Of the 1 355 clinical isolates,gram negative bacilli and gram positive cocci accounted for 64.6%(876/1 355) and 35.4%(479/1 355) respectively.About 23.2% of the S.aureus isolates were identified as MRSA,80.7% of the coagulase negative Staphylococcus isolates were identified as MRCNS.Overall,about 97.5% of the Streptococcus pneumoniae strains were sensitive to penicillin.No strain of gram-positive cocci was found resistant to glycopeptides.Isolates of Enterobacteriaceae were highly sensitive to carbapenems.About 58.4%(153/262) of the E.coli isolates and 39.9%(55/138) of the K.pneumoniae isolates were ESBLs-producing strains.One carbapenem-resistant strain of Escherichia coli was isolated from blood culture.Phenotype test showed that it produced metalloenzyme.The percentage of the A.baumannii isolates resistant to imipenem,meropenem,cefoperazone-sulbactam,or minocycline was lower than 20%.The prevalence of pan-resistant strains in A.baumannii(19.2%,10/52) was significantly higher than the data in 2009(3.3%,3/90).Not more than 10% of P.aeruginosa isolates were resistant to imipenem,meropenem,ciprofloxacin,or levofloxacin.Stenotrophomonas maltophilia strains were relatively susceptible to sulfamethoxazole-trimethoprim,levofloxacin,minocycline with lower resistance rate.No strains of Haemophilus influenzae or Moraxella catarrhalis were found resistant to amoxicillin-clavulanate or cefotaxime.Conclusions The resistant pattern of clinical bacterial isolates has changed evidently in 2011 compared to the previous monitoring data.However,the gram-negative bacilli were still highly sensitive to carbapenems.The prevalence of Streptococcus pneumoniae and Haemophilus influenzae has increased.Periodic surveillance of antimicrobial resistance is most important and valuable for understanding the trend of antimicrobial resistance and rational antimicrobial therapy.