Escherichia coli producing ESBL.

When Escherichia coli produces Extended-Spectrum Beta-Lactamase (ESBL) enzymes, it means that the bacteria have acquired a mechanism to break down and resist many beta-lactam antibiotics, including penicillins (e.g., piperacillin/tazobactam), cephalosporins (e.g., ceftriaxone, cefotaxime, ceftazidime), and monobactams (aztreonam).

Plasmids encoding ESBL-type enzymes often carry resistance determinants for multiple classes of antimicrobial agents (e.g., sulfonamides, quinolones, aminoglycosides).

ESBL-producing E. coli usually remain susceptible to carbapenems.