CTX-M-190, a Novel β-Lactamase Resistant to Tazobactam and Sulbactam, Identified in an Escherichia coli Clinical Isolate.

Authors :: Shen Z
Ding B
Bi Y
Wu S
Xu S
Xu X
Guo Q
Wang M
Source :: Antimicrobial agents and chemotherapy [Antimicrob Agents Chemother] 2016 Dec 27; Vol. 61 (1). Date of Electronic Publication: 2016 Dec 27 (Print Publication: 2017).
Publication Year :: 2016
Abstract: A novel β-lactamase, CTX-M-190, derived from CTX-M-55 by a single substitution of Ser for Thr at position 133 (Ser133Thr), was identified in a natural Escherichia coli clinical isolate. CTX-M-190 exhibited potent hydrolytic activity against cefotaxime, with a k <subscript>cat</subscript> /K <subscript>m</subscript> ratio of 14.5 μM <superscript>-1</superscript> s <superscript>-1</superscript> , and was highly resistant to inhibition by the β-lactamase inhibitors tazobactam and sulbactam, whose 50% inhibitory concentrations were 77- and 55-fold higher, respectively, for CTX-M-190 than for CTX-M-55. bla <subscript>CTX-M-190</subscript> was located within the genetic platform ISEcp1-bla <subscript>CTX-M</subscript> -orf477, which was harbored by a 70-kb IncI1 plasmid.<br /> (Copyright © 2016 American Society for Microbiology.)

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