SHV-14, a Novel β-Lactamase Variant in Klebsiella pneumoniae Isolates from Nijmegen, The Netherlands

Four ceftazidime-resistant isolates of a Klebsiella pneumoniae strain were collected from intensive care unit patients in Nijmegen, The Netherlands. These isolates had TEM-29 and SHV-14 β-lactamases. SHV-14 is a novel variant, with two substitutions compared with the sequence of SHV-1: Ile8Phe and Arg43Ser. Its gene also had a silent C→T mutation at nucleotide 481. The SHV-14 enzyme had slightly higher V(max) rates than SHV-1 for oxyimino-aminothiazolyl cephalosporins, but this activity was insufficient for the enzyme to count as an extended-spectrum β-lactamase.