Characterization of a Novel Extended-Spectrum TEM-Type β-Lactamase,TEM-164,in a Clinical Strain of Klebsiella pneumoniae in Tunisia

Abstract

Klebsiella pneumoniae ML1708 exhibited a multiresistance phenotype, including resistance to all β-lactams tested, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline, and streptomycin. The double-disk synergy test was positive. ML1708 harbored a 50 kb conjugative plasmid that encoded a β-lactamase of pI 5.5. The corresponding bla gene was identified by polymerase chain reaction and sequencing as a bla_TEM gene. The deduced protein sequence revealed a new variant of TEM-1 β-lactamase designated TEM-164. TEM-164 contains the unusual following mutations: L40V and I279T. These modifications may result in a change of the pI to 5.5 and hydrolyze cefotaxime and ceftazidime.