Growing concern about ESBLs in farm animals
In the mid-1980s, a new group of enzymes described as extended-spectrum β-lactamases (ESBLs) were identified in resistant nosocomial isolates ofKlebsiella spp.. ESBLs have proved to be difficult to treat, having resistance to the majority of β-lactam antibiotics used in veterinary and human medicine, including penicillins, expanded-spectrum cephalosporins and related oxyimino- β-lactams.

Spreading of ESBL
Research suggests the spread of ESBL-producing bacteria is worsening, with many fast-spreading β-lactamases now endemic in certain parts of world including CTX-M ESBLs in European, Asian and South American countries. Understanding resistance mechanisms and the implementation of various critical control points along the food production chain has the potential for decreasing risk of ongoing spread of these important resistance genes.