Low minimum inhibitory concentrations associated with the tetracycline-resistance gene tet(C) in Escherichia coli.
Twenty-eight Escherichia coli isolates from various animal and environmental sources with defined tetracycline-resistance genotypes for tet(A), tet(B), and tet(C) were tested for their susceptibility to tetracycline by means of both broth microdilution and Etest. All tet(C)-positive isolates had tetracycline minimum inhibitory concentrations clustering around an intermediate susceptibility range of 2 to 16 microg/mL. Detecting tet(C)-positive isolates by means of susceptibility testing may therefore be difficult with use of the current breakpoint for tetracycline of the Clinical and Laboratory Standards Institute guidelines.
Chalmers
Gabhan
G
Department of Pathobiology, University of Guelph, Ontario, Canada.
Kozak
Gosia K
GK
Hillyer
Elizabeth
E
Reid-Smith
Richard J
RJ
Boerlin
Patrick
P
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D012097:Repressor Proteins / Q000235:genetics*; D013752:Tetracycline / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D012097:Repressor Proteins; C107173:TetC protein, Bacteria; D013752:Tetracycline