Transmission of Salmonella enterica serotype Typhimurium in poultry with and without antimicrobial selective pressure |
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Authors: | Bauer-Garland J Frye J G Gray J T Berrang M E Harrison M A Fedorka-Cray P J |
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Institution: | US Department of Agriculture, Agricultural Research Service, Bacterial Epidemiology and Antimicrobial Resistance Research Unit, Athens, GA 30605, USA. |
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Abstract: | AIMS: To determine the effect of antimicrobial selective pressure on the transmission of antimicrobial resistant and sensitive strains of Salmonella in poultry. METHODS AND RESULTS: Eight pens housed 12 broiler chicks each. Two chicks in four of the pens were inoculated with a Salm. Typhimurium strain resistant to 12 antimicrobials (including tetracycline), and two chicks in each of the four other pens were inoculated with a strain sensitive to all antimicrobials tested. Two pens inoculated with each strain were treated with chlortetracycline and two were not. Chicks were killed on day 7 and caeca were cultured for Salmonella. Experiments were performed independently twice. Chicks exposed to pen mates inoculated with the resistant strain and treated with tetracycline were 90% positive for Salmonella; whereas 60% of chicks given no antimicrobials were positive. Chicks exposed to the sensitive strain were 95% positive with tetracycline treatment and 90% positive without treatment. CONCLUSIONS: A multidrug-resistant Salm. Typhimurium strain had significantly increased transmission when chicks were treated with tetracycline. Transmission of a sensitive strain was not inhibited by antimicrobial selective pressure at recommended therapeutic dose. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that antimicrobial usage may influence the transmission of antimicrobial-resistant pathogens in poultry. |
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Keywords: | antimicrobial resistance antimicrobial selective pressure poultry Salmonella Typhimurium tetracycline transmission |
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