Potential adaptive amino acid substitutions in TEM-1 identified from genetic selections for tazobactam resistance codon substitutions.

aNumbering according to Ambler et al. [28].bAmino acid substitutions observed in natural alleles of TEM-1 with increased resistance to b-lactam antibiotics or ß-lactamase inhibitors (http://www.lahey.org/studies/temtable.asp). Amino acid substitutions underlined are found in alleles with increased inhibitor resistance [29].cAmino acid substitutions in bold were observed with a single base change in the codon. * means that although the amino acid substitution can occur with a single base change, such a change was not observed here.dOf the amino acid substitution in this study.eFor the amino acid substitutions found in this study, the number of unique codons observed out of the possible number of unique codons is reported.