Effects of Antimicrobial Treatment on Selection of Resistant Escherichia coli in Broiler Fecal Flora

• Type: Article in International Scientific Journal
• Date: 2008

Authors

da costa, pm (Author) ICBAS; bica, a (Author) Other; vaz-pires, p (Author) ICBAS; bernardo, f (Author) Other

Journal

Title: Microbial Drug Resistance

Vol. 14

Pages: 299-306

ISSN: 1076-6294

Publisher: Mary Ann Liebert

Indexing

ISI Web of Knowledge - 17 Citations

Scopus - 20 Citations

Scientific classification

FOS: Medical and Health sciences > Health sciences

Other information

Authenticus ID: P-003-TNY

DOI: 10.1089/mdr.2008.0859

Abstract (EN): Under field conditions, three commercial antimicrobials were sequentially prescribed to 16,000 broiler chickens during their rearing period, via drinking water using subtherapeutic levels for 3 days. A control group of 16,000 broilers was placed in the same controlled environment poultry house. Feed diet and fecal samples from both groups were collected periodically. One sample of the drinking water along with samples from the broiler house environment was also collected I day before bird placement. Samples were plated onto Tergitot BCIG Agar media, a maximum of 26 Escherichia coli were isolated per sample, and their susceptibility was tested to 12 antimicrobials by disk diffusion agar method. We have observed that day-old chicks were rapidly colonized by new antibiotic-resistant patterns shortly after treatment with lincomycin associated with spectinomycin. After medication with the second (sulfadiazine with trimethoprim) and third (tylosin) antimicrobials, a more radical displacement was observed, and, Concurrently, antimicrobial resistance phenotypes have become more complex. In contrast, more than 70%, of the strains isolated in control group during the experiment displayed exactly the same resistance pattern found in the day-old chicks. This study provides clear evidence that a sequential medication of a broiler flock, with different antimicrobial classes during short periods of time for prophylactic objectives, was accompanied by a dramatic increase in both antimicrobial resistance rates and phenotype diversity of E. coli strains.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8