Objective      To investigate antimicrobial resistance of clinical isolates from 44 hospitals submitted to Guangdong Surveillance of Antimicrobial Resistance in the year of 2012 and to learn the features of bacterial resistance in this region by comparing the local data of 2010.       Methods      Disc diffusion test (K-B methods) was employed to study the antimicrobial resistance of 66 470 strains of bacteria isolates. WHONET5.6 was applied for analysis according to the 2012 National Committee for Clinical Laboratory Standards (CLSI).       Results      Of 66470 clinical isolates

Gram negative bacilli and Gram positive cocci accounted for 72.1% (47 955/66 470) and 27.9% (18 515/66 470)

respectively. The detection rates of methicillin-resistant strains was 39.6% in Staphylococcus.aureus and 73.0% in coagulase negative Staphylococcus. No vancomycin intermediate Staphylococcus aureus (VISA) or vancomycin resistant Staphylococcus aureus (VRSA) isolate was found. According to 2012 CLSI criterion

2.6% Staphylococcus. pneumonia isolates were penicillin-resistant (PRSP). The prevalence of extended spectrum β lactamase (ESBLs)-producing strains was 54.7% in E. coli

36.8% in Klebsiella spp. and 18.9% in Proteus mirabilis isolates. ESBLs-producing Enterobacteriaceae strains showed higher antibiotic resistance to monitored drugs than non-ESBLs-producing strains. The lowest resistance rates for Acinetobacter spp.(A.baumannii accounting for 92％) were minocycline (21.1%)

cefoperazone/sulbactam (25.9%) amikacin(32.5%). Compare with the data in 2010

the resistant rates of A.baumannii to imipenem and meropenem was increased from 29.7% to 46.1% and 31.6% to 44.2%

respectively. But the rates were still lower compare to the national data (imipenem 53.5% and meropenem 51.9%).       Conclusion      The bacterial resistance situation is ameliorated

but still quite serious

especially for A.baumannii to carbopenem. The increased detection rate of carbopenem-resistant A.baumannii poses a serious threat to clinical practice. It is urgent to enhance the surveillance of bacterial resistance to guide the   use of antibiotics.