Title

Effect of Bacitracin on Tetracycline Resistance in Escherichia coli and Salmonella

Document Type

Article

Publication Date

9-2009

Keywords

bacitracin, tetracycline, antibiotic, antibiotic resistance, antimicrobial, growth promotant, Escherichia coli, salmonella

Abstract

Tetracyclines and bacitracin are used extensively as a growth promotant and a therapeutic, respectively in livestock. In this study, we test whether there is an interaction between bacitracin and tetracycline that can select for an increase in microbial tetracycline sensitivity, using Escherichia coli and Salmonella as a model. We found viain vitro studies that bacitracin at sublethal concentrations preferentially selects for outgrowth of tetracycline-sensitive bacteria from among a population of tetracycline-resistant and tetracycline-sensitive E. coli and Salmonella strains. Most of the bacterial strains employed in our study were shown by PCR to possess the tetracycline resistance gene tet(A) or tet(C), either of whose activity is associated with tetracycline efflux. Bacitracin could be substituted for the lipophylic chelator, fusaric acid, used as a positive selective agent for tetracycline sensitivity. Together, these observations suggest that bacitracin-mediated selection for tetracycline sensitivity alters the function of tetracycline efflux proteins. Using bacitracin and tetracycline simultaneously may improve the effectiveness of the antibiotics, while decreasing the risk of selecting for a population of tetracycline-resistant microorganisms.

Publication Title

Veterinary Microbiology

Volume

138

Issue

3-4

First Page

353

Last Page

360

DOI of Published Version

doi:10.1016/j.vetmic.2009.03.031

Publisher

Elsevier

Rights

Copyright © 2009 Elsevier