Objective To investigate the bacterial resistance in nationwide and understand the distribution of bacterial and resistance trend.MethodsThe 6507 clinical isolates were collected from 19 hospitals in 17 cities.The susceptibility tests were performed using agar dilution method recommended by Clinical and Laboratory Standards Institute (CLSI) in central laboratory.The values of MIC50,MIC90 and MICrange were calculated by SPSS 17.0 and the susceptibilities of isolates to antimicrobial agents were determined by using CLSI (2010) guideline.Of all 6507 isolates,4691 strains were collected from target wards and 1816 were isolated from others wards.ResultsAmong 4691 strains,1156 were Gram-positive (24.6％ ) and 3535 were Gram-negative (75.4％).Based on the minimum inhibitory concentration results,the prevalence of methicillin resistant Stapylococcus aureus and methicillin resistant Stapylococcus epidermidis are 51.6％ ( 325/630 ) and 87.0％ ( 228/262 ) respectively.Staphylococci showing intermediate or full resistance to vancomycin were not observed. Coagulase negative Staphylococci showed 2.5％ (16/642)intermediate rate and 1.6％ ( 10/642 ) full resistance rate to teicoplanin,and showed 0.5％ ( 3/642 )resistance rate to linezolid.Antibiotic resistance rate of Enterococcus faecalis to ampicillin was 17.1％(19/111),while the resistance rate of Enterococcus faecium to ampicillin reached up to 85.0％(164/193).Three Enterococcus faecium were resistant to glycopeptides.The prevalence of penicillin resistance Streptococcus pneumoniae and penicillin intermediate Streptococcus pneumoniae were 41.2％ ( 145/352) and 37.2％ (131/352) respectively based on oral penicillin criterion,while the prevalence were 0.0％ (0/352) and 6.0％(21/352) based on vein to non-meningitis criterion.A vast majority of Enterobacteriaceae maintained high susceptibility to carbapenems,with resistance rate less than 2.0％.In addition,tigecycline,moxalactam,fosfomycin and amikacin displayed desirable antibacterial activity against Enterbacteriaceae,and resistance rates to these drugs were all less than 10.0％.For non-fermenting Gramnegative isolates,resistance rate of Pseudomonas aeruginosa and Acinetobacter baumannii to imipenem were 23.1％ ( 139/601 ) and 53.5％ (419/784) respectively.Resistance rate of Acinetobacter baumannii was much higher than that during the period 2007 - 2008.Colistin,tigecycline,minocycline and fosfomycin demonstrated good antibacterial activity against Acinetobacter baumannii in vitro.Conclusions Compared with MOHNARIN 2007 -2008year surveillance results, significant increase in resistance rate of Acinetobacter baumannii was demonstrated.Resistant strains to linezolid and tigecycline were found.Bacterial resistance has been a widespread problem in our country,which requires much more attention.