oa Southern African Journal of Epidemiology and Infection - Multidrug-resistant (MDR) gramnegative fermenters : "our worst nightmare?" : editorial
ß-lactamase enzymes can be broadly divided into those with a serine residue at the active site and metallo-enzymes utilising zinc as a co-factor. Both are ancient enzymes with the former from their current sequence diversity, estimated to have evolved over the past two billion years. Since ß-lactams have been used in the clinical setting, ß-lactamases have coevolved along with each new antibiotic development. Initially penicillinase-producing Staphylococcus aureus and Neisseria gonorrhoeae and subsequently broader spectrum enzymes such as the extended-spectrum ß-lactamases (ESBLs) and the carbapenem-hydrolysing ß-lactamases (carbapenemases) produced in response to the introduction of cephalosporins and carbapenems, have appeared. Currently, over 400 different types of clinically relevant ß-lactamases have been described (www.lahey.org/studies/webt.htm) but the ESBLs have probably had a greater impact than any other group.
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