Rapid screening method for detection of antimicrobial resistance in commensal microbiota of chicken farms
The commensal flora of the gut is considered the most important reservoir for antimicrobial resistant (AMR) bacteria and genetic elements encoding for AMR. There is a need for sensitive and cost-effective screening methods that quantify AMR and that can be applied to the investigation of AMR on farms. Between mid September and December 2017, ViParc will be conducting a pilot study in order to assess the effectiveness of direct plating methods compared with the conventional (and laborious!) methods based on individual isolation of bacteria such as Escherichia coli.
The Direct Plating Method (DPM) consists of the direct application of antimicrobial-containing discs onto agar inoculated with chicken fecal material to detect antimicrobial resistance organisms. The inhibition zone diameters are measured. At the same time, resistant clones could be picked up inside inhibition zones and analyzed further. In parallel, E. coli will be isolated from samples of each visit and determined antimicrobial susceptibility by the disk diffusion method using the procedure of the Clinical and Laboratory Standards Institute.
Inhibition zone diameters will be used for determining appropriate interpretive breakpoints for the direct plating method. Outcomes of the study should be a foundation for an ideal method to be applied on a large number of samples in ViParc project.
In this pilot study, chicken faeces from 12 ViParc farms will be investigated at three points during production cycle (day-old, mid-, and end-of production). In order to maximise the chance of finding differences in results, farms have been selected based on the amount of antimicrobials used during the first cycle.