Characterization of a novel IMP-28 metallo-β-lactamase from a Spanish Klebsiella oxytoca clinical isolate

Abstract

An isolate of Klebsiella oxytoca carrying a novel IMP metallo-β-lactamase was discovered in Madrid, Spain. The bla(IMP-28) gene is part of a chromosomally located class I integron. The IMP-28 k(cat)/K(m) values for ampicillin, ceftazidime, and cefepime and, to a lesser extent, imipenem and meropenem, are clearly lower than those of IMP-1. The His306Gln mutation may induce important modifications of the L3 loop and thus of substrate accessibility and hydrolysis and be the main reason for this behavior.