Phenotypic antimicrobial resistance (AMR) of avian pathogenic <i>Escherichia coli</i> (APEC) from broiler breeder flocks between 2009 and 2018
Creators: name: Oliveira, João Marco
name: Cardoso, Margarida Fonseca
name: Moreira, Fernando A.
name: Müller, Alexandra
Publisher: name: Taylor & Francis
Year: 2022
Subjects: subject: Space Science
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Genetics
subject: Molecular Biology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: Ecology
subject: Immunology
subject: FOS: Clinical medicine
subject: 69999 Biological Sciences not elsewhere classified
subject: Cancer
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: 60506 Virology

description: Colibacillosis is one of the most important diseases in poultry production. The use of antimicrobials remains a therapeutic cornerstone for avian pathogenic <i>E. coli</i> (APEC), thereby contributing to the development of antimicrobial resistance (AMR). The aim of this study was to characterize AMR in broiler breeder flocks reared under commercial conditions. Data covering 10 years, from 2009 to 2018, were used to evaluate the phenotypic AMR of 264 APEC isolates obtained from 158 broiler breeder flocks of a large company in Portugal. The APEC isolates were tested against eleven antimicrobials by the Kirby-Bauer disc diffusion test. The annual proportion of AMR was calculated by dividing the number of APEC isolates with phenotypic resistance by the total number of APEC isolated that year. Similarly, the overall AMR of the whole period was calculated. The relationship of antimicrobial resistance with time (years) was investigated with a generalized linear model using logistic regression. The overall AMR of the 10-year period was: amoxicillin 78%, ampicillin 73.5%, tetracycline 63.3%, doxycycline 56.4%, apramycin 34.5%, neomycin 68.2%, enrofloxacin 32.6%, flumequine 39.4%, co-trimoxazole 47.7%, florfenicol 46.6% and lincospectin 66.3%. Over time, a significant decrease in AMR was observed for amoxicillin and ampicillin, neomycin, flumequine, co-trimoxazole, florfenicol and lincospectin. Multidrug resistance (MDR) decreased from 100% in 2009 to 48% in 2018. Only seven (2.7%) APEC strains were fully susceptible to all tested antimicrobials. The decrease over time of AMR in APEC likely reflects the efficacy of manifold improvements in broiler breeder production systems. A further reduction in AMR is still desirable. RESEARCH HIGHLIGHTSDecreasing trend of antimicrobial resistance in avian pathogenic <i>E. coli</i> over time.Over 50% of isolates still resistant to amoxicillin, tetracycline and doxycycline.Multidrug resistance decreased from 100% in 2009 to 48% in 2018.Further reduction of antimicrobial resistance in broiler breeders desirable. Decreasing trend of antimicrobial resistance in avian pathogenic <i>E. coli</i> over time. Over 50% of isolates still resistant to amoxicillin, tetracycline and doxycycline. Multidrug resistance decreased from 100% in 2009 to 48% in 2018. Further reduction of antimicrobial resistance in broiler breeders desirable.