Skip Navigation



JAC Advance Access published online on June 14, 2005
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dki189
This Article
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
56/2/297    most recent
dki189v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Randall, L. P.
Right arrow Articles by Piddock, L. J. V.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Randall, L. P.
Right arrow Articles by Piddock, L. J. V.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© British Crown Copyright 2005, Dstl-published with the permission of the Controller of Her Majesty's Stationery Office.
Received March 2, 2005
Revised May 10, 2005
Accepted May 10, 2005

Original article

Fluoroquinolone treatment of experimental Salmonella enterica serovar Typhimurium DT104 infections in chickens selects for both gyrA mutations and changes in efflux pump gene expression

Luke P. Randall 1*, Deborah J. Eaves 2, Sue W. Cooles 1, V. Ricci 2, Antony Buckley 2, Martin J. Woodward 1, and Laura J. V. Piddock 2

1 Department of Food and Environmental Safety, Veterinary Laboratories Agency, New Haw, Surrey KT15 3NB, UK
2 Antimicrobial Agents Research Group, Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, UK

* To whom correspondence should be addressed.
Luke P. Randall, E-mail: l.randall{at}vla.defra.gsi.gov.uk


  Abstract

Objectives: To determine the efficacy of enrofloxacin (Baytril) in chickens in eradicating three different resistance phenotypes of Salmonella enterica and to examine the resistance mechanisms of resulting mutants.

Methods: In two separate replicate experiments (I and II), three strains of Salmonella enterica serovar Typhimurium DT104 [strain A, fully antibiotic-sensitive strain; strain B, isogenic multiple antibiotic-resistant (MAR) derivative of A; strain C, veterinary penta-resistant phenotype strain containing GyrA Phe-83], were inoculated into day-old chicks at ~103 cfu/bird. At day 10, groups of chicks (n = 10) were given either enrofloxacin at 50 ppm in their drinking water for 5 days or water alone (control). Caecal contents were monitored for presence of Salmonella and colonies were replica plated to media containing antibiotics or overlaid with cyclohexane to determine the proportion of isolates with reduced susceptibility. The MICs of antibiotics and cyclohexane tolerance were determined for selected isolates from the chicks. Mutations in topoisomerase genes were examined by DHPLC and expression of marA, soxS, acrB, acrD and acrF by RT-PCR.

Results: In experiment I, but not II, enrofloxacin significantly reduced the numbers of strain A compared with the untreated control group. In experiment II, but not I, enrofloxacin significantly reduced the numbers of strain B. Shedding of strain C was unaffected by enrofloxacin treatment. Birds infected with strains A and B gave rise to isolates with decreased fluoroquinolone susceptibility. Isolates derived from strain A or B requiring >128 mg/L nalidixic acid for inhibition contained GyrA Asn-82 or Phe-83. Isolates inhibited by 16 mg/L nalidixic acid were also less susceptible to antibiotics of other chemical classes and became cyclohexane-tolerant (e.g. MAR).

Conclusions: These studies demonstrate that recommended enrofloxacin treatment of chicks rapidly selects for strains with reduced fluoroquinolone susceptibility from fully sensitive and MAR strains. It can also select for MAR isolates.

Keywords: MAR; cyclohexane tolerance; quinolone resistance.
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 J Antimicrob ChemotherHome page
M. A. Webber, L. P. Randall, S. Cooles, M. J. Woodward, and L. J. V. Piddock
Triclosan resistance in Salmonella enterica serovar Typhimurium
J. Antimicrob. Chemother., July 1, 2008; 62(1): 83 - 91.
[Abstract] [Full Text] [PDF]

Home page
 J Antimicrob ChemotherHome page
L. P. Randall, M. C. Bagnall, K. A. Karatzas, N. C. Coldham, L. J. V. Piddock, and M. J. Woodward
Fitness and dissemination of disinfectant-selected multiple-antibiotic-resistant (MAR) strains of Salmonella enterica serovar Typhimurium in chickens
J. Antimicrob. Chemother., January 1, 2008; 61(1): 156 - 162.
[Abstract] [Full Text] [PDF]

Home page
 Antimicrob. Agents Chemother.Home page
L. P. Randall, S. W. Cooles, N. C. Coldham, K. S. Stapleton, L. J. V. Piddock, and M. J. Woodward
Modification of Enrofloxacin Treatment Regimens for Poultry Experimentally Infected with Salmonella enterica Serovar Typhimurium DT104 To Minimize Selection of Resistance
Antimicrob. Agents Chemother., December 1, 2006; 50(12): 4030 - 4037.
[Abstract] [Full Text] [PDF]

Home page
 J DAIRY SCIHome page
M. J. Raymond, R. D. Wohrle, and D. R. Call
Assessment and promotion of judicious antibiotic use on dairy farms in Washington State.
J Dairy Sci, August 1, 2006; 89(8): 3228 - 3240.
[Abstract] [Full Text] [PDF]

Home page
 J Antimicrob ChemotherHome page
L. P. Randall, N. G. Coldham, and M. J. Woodward
Detection of mutations in Salmonella enterica gyrA, gyrB, parC and parE genes by denaturing high performance liquid chromatography (DHPLC) using standard HPLC instrumentation
J. Antimicrob. Chemother., October 1, 2005; 56(4): 619 - 623.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.