Modelling the impact of antimicrobial use and external introductions on commensal E. coli colistin resistance in small‐scale chicken farms of the Mekong delta of Vietnam

Abstract

Colistin is a critically important antimicrobial for human medicine, and colistin‐resistant Escherichia coli are commonly found in poultry and poultry products in Southeast Asia. Here, we aim at disentangling the within‐farm and outside‐farm drivers of colistin resistance in small‐scale chicken farms of the Mekong delta of Vietnam. Nineteen Vietnamese chicken farms were followed up along a whole production cycle, during which weekly antimicrobial use data were recorded. At the beginning, middle and end of each production cycle, commensal E. coli samples from birds were collected, pooled and tested for colistin resistance. Twelve models were fitted to the data using an expectation–maximization algorithm and compared. We further tested the spatial clustering of the occurrence of resistance importations from external sources using the local Moran's I statistic. In the best model, colistin resistance in E. coli from chickens was found to be mostly affected by importations of resistance, and, to a lesser extent, by the use of antimicrobials in the last 1.73 weeks [0.00; 2.90], but not by the use of antimicrobials in day‐olds, nor their colistin resistance carriage from hatchery. The occurrence of external source importations proved to be sometimes spatially clustered, suggesting a role of local environmental sources of colistin resistance.

Longitudinal Study on Extended-Spectrum Beta-Lactamase-E. coli in Sentinel Mallard Ducks in an Important Baltic Stop-Over Site for Migratory Ducks in Germany

“…Among wild animals, a special role in spreading AMR has been proposed for wild birds as they are able to migrate over vast distances [ 28 , 29 , 45 , 46 , 47 , 48 ]. The studies range from investigations of very remote areas with scarce human influence, such as Antarctica or Alaska [ 26 , 49 ], to areas with high human influence [ 50 ], such as poultry farms [ 51 , 52 , 53 , 54 ]. While in the study from Rabbia et al [ 55 ] no AMR bacteria could be identified in fecal samples from wild birds, positive results from environmental samples close to human activities, such as waste water treatment plants, showed a potential risk.…”

Impact of antimicrobial use on abundance of antimicrobial resistance genes in chicken flocks in Vietnam

“… 16 Using longitudinal data from chicken flocks in the Mekong Delta (Vietnam), a modelling study on colistin resistance indicated that AMU in the early stage of production or introduction from hatcheries is far less determinant than importation from the environment and use in latter stages. 17 …”