The objective of this study was to investigate the susceptibility of hospital-and community-associated E.coli and K.pneumoniae isolated from patients with intra-abdominal infections in China.From 2002 to 2011, the minimum inhibitory concentrations (MICs) of 12 antibiotics against 3,074 E.coli and 1,025 K.pneumoniae from 23 centers located at 16 cities were determined by broth microdilution method.During the ten-years study period, ertapenem, imipenem, amikacin and piperacillin-tazobactarn remained high and stable activity against E.coli and K.pneumoniae strains regardless of isolates source (HA/CA) and ESBL production.However, the susceptibility of E.coli to cephalosporins and ampicillin-sulbactam decreased dramatically during the ten years, especially for the CA strains.The susceptibility of HA E.coli and K.pneumoniae strains to cephalosporins and ampicillin-sulbactam were lower than that of CA strains in most of the study years.During the whole study period, the ESBL rates for E.coli isolates from IAIs increased from 36.1% in 2002-2003 to 68.1% in 2010-2011 (P<0.001).Correspondingly, the ESBL rates in HA isolates increased from 52.2% in 2002-2003 to70.0% in 2010-2011 (P=0.001), and in CA isolates from 19.1% in 2002-2003 to 61.6% in 2010-2011 (P<0.001).The ESBL production rate in K.pneumoniae remained 30.1-39.3% of the total isolates with no significant change during the ten years.In conclusion, carbapenems retained the highest susceptibility rates over the ten-year study period against HA and CA E.coli and K.pneumoniae.High prevalence of ESBL in HA E.coli and fast-growing resistance development in CA E.coli severely limited the empirical use of the third-and fourth-generation cephalosporins in the therapy of intra-abdominal infections in China.