Characterization of an inhibitor-resistant enzyme IRT-2 derived from TEM-2 β-lactamase produced by Proteus mirabilis strains

Abstract

Ten clincial isolates of Proteus mirabilis were found to produce an inhibitor-resistant TEM β-lactamase (IRT) in association with a TEM-1 enzyme. The IRT enzyme was derived from TEM-2. The bla_IRT gene differs from bla_TEM-2 gene by one point mutation which leads to the amino-acid substitution Arg→Ser at position 244, as observed for the original IRT-2 enzyme derived from TEM-1 reported in Escherichia coli. This is the first report of an IRT β-lactamase derived from TEM-2.