Open AccessIn Vitro Activity of Ceftolozane-Tazobactam as Determined by Broth Dilution and Agar Diffusion Assays against Recent U.S. Escherichia coli Isolates from 2010 to 2011 Carrying CTX-M-Type Extended-Spectrum β-Lactamases
Author(s) -
Mark Estabrook,
Brianne Bussell,
Susan L. Clugston,
Karen Bush
Publication year - 2014
Publication title -
journal of clinical microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.349
H-Index - 255
eISSN - 1070-633X
pISSN - 0095-1137
DOI - 10.1128/jcm.02357-14
Subject(s) - broth microdilution , etest , microbiology and biotechnology , agar , tazobactam , agar dilution , agar dilution method , escherichia coli , biology , in vitro , chemistry , bacteria , minimum inhibitory concentration , antibiotics , antibiotic resistance , biochemistry , gene , imipenem , genetics
Ceftolozane MIC50 /MIC90 s were 4/8 μg/ml when tested against 26 CTX-M-14-type-producing isolates and 64/>64 μg/ml against 219 CTX-M-15-type-producing isolates. The addition of 4 μg/ml tazobactam lowered the ceftolozane MIC50 /MIC90 s to ≤0.25/0.5 μg/ml by broth microdilution and Etest. The zone diameters for the ceftolozane-tazobactam disks were 23 to 29 mm for 92.2% of the isolates.
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