Use of avilamycin for growth promotion and avilamycin-resistance among Enterococcusfaecium from broilers in a matched case-control study in France

We assessed the putative link between avilamycin-resistant Enterococcus faecium carriage and avilamycin consumption in broilers. As part of the French programme of monitoring for antimicrobial resistance, broilers sampled at slaughterhouse in 1999 and 2000 and carrying avilamycin-resistant E. faecium were matched by slaughterhouse, slaughter month and production type (free-range, standard, light) with control broilers carrying avilamycin-susceptible strains. History of antibiotics consumption (either for growth promotion or therapeutic purpose) in the broiler flocks sampled was collected from the monitoring programme and consumption of each antibiotic class was screened as a potential risk factor. Avilamycin was a risk factor for avilamycin-resistant E. faecium carriage: OR = 2.3.