title: Antimicrobial resistance of Escherichia coli isolated in newly-hatched chickens and effect of amoxicillin treatment during their growth.
abstract: The use of antimicrobials in food animals is the major determinant for the propagation of resistant bacteria in the animal reservoir. However, other factors may also play a part, and in particular vertical spread between the generations has been suggested to be an important transmission pathway. The objective of this paper was to determine the resistance patterns of Escherichia coli isolated from newly-hatched chickens as well as to study the antibiotic pressure effect when amoxicillin was administered during their growing period. With this aim, meconium from 22 one-day-old Ross chickens was analysed. In addition, during their growth period, amoxicillin treatments at days 7, 21 and 35 were carried out. Results showed a high number of E. coli-resistant strains were isolated from the treated one-day-old chickens, and were the highest for β-lactams group, followed by quinolone and tetracyclines. After treatment with amoxicillin, the highest percentage of resistances were detected for this antibiotic compared to the others analysed, with significant differences in resistance percentages between control and treated broilers detected in relation to ampicillin, cephalothin, streptomycin, kanamycin, gentamicin, chloramphenicol and tetracycline. Differences in resistances to ciprofloxacin and nalidixic acid between control and treated animals were not observed and there was lack of resistance for amikacin and ceftriaxone. These results suggest the possibility of vertical transmission of resistant strains to newly-hatched chicks from parent flocks, and seem to indicate that the treatment with amoxicillin increased the resistance of E. coli to other antibiotics.
authors.affiliation: a Biotechnology Department. Centro Avanzado de Microbiología de Alimentos , Universitat Politècnica de València , Valencia , Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Jiménez-Belenguer
authors.affiliation: b Institute of Food Engineering for Development (IUIAD), Food Technology Department , Universitat Politécnica de Valencia , Valencia , Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Doménech
authors.affiliation: c Centro de Tecnología Animal CITA-IVIA , Castellon , Spain.
authors.forename: Arantxa
authors.initials: A
authors.lastname: Villagrá
authors.affiliation: d Biotechnology Department , Universitat Politècnica de València , Valencia , Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Fenollar
authors.affiliation: a Biotechnology Department. Centro Avanzado de Microbiología de Alimentos , Universitat Politècnica de València , Valencia , Spain.
authors.forename: Maria Antonia
authors.initials: MA
authors.lastname: Ferrús
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002645:Chickens / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary*; D008297:Male; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D009268:Nalidixic Acid / Q000494:pharmacology; D011201:Poultry Diseases / Q000382:microbiology* / Q000635:transmission; D015363:Quinolones / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D015363:Quinolones; D009268:Nalidixic Acid; D000658:Amoxicillin
keywords: E coli; Newborn chickens; antimicrobial resistance; vertical transmission