 Carbapenems, including ertapenem, imipenem and meropenem, are the drugs of choice used for severe ESBL-producing bacterial infections. Failure to detect ESBL at the presence of AmpC β-lactamase might result in an important clinical concern because 4th generation cephalosporins, which are stable to AmpC β-lactamase, is not a drug of choice for severe infections caused by ESBLs-producing isolates. Fluoroquinolone-resistance in ESBL-producing Enterobacteriacea is common. In this study, the investigators will use isolates of Enterobacteriacea collected from different hospitals isolates offered by the Taiwan Surveillance of Antimicrobial Resistance TSAR program to investigate the susceptibility of ertapenem and five other antimicrobial agents against ESBLs-producing Enterobacteriacea. 