Many antibiotics have chemical bonds such as amides and
esters which are hydrolytical susceptible. Several enzymes
are known to ruin antibiotic activity by targeting and cleaving
these bonds. These enzymes can often be excreted. Extendedspectrum
b-lactamases (ESBLs) mediate resistance to all
penicillins, third generation cephalosporins (e.g. ceftazidime,
cefotaxime, and ceftriaxone) and aztreonam, but not to
cephamycins (cefoxitin and cefotetan) and carbapenems