Epidemiological assessment of the factors associated with antimicrobial use in French free-range broilers.

BACKGROUND: Although the poultry sector accounts for a major portion of global antimicrobial consumption, few studies have explored the factors which influence antimicrobial use (AMU) in poultry farms in Europe. We performed a matched case-control study in traditional free-range broiler farms in France during 2016 to evaluate the effect of technical factors and farmers' perceptions of health problems on the probability of AMU. In total, 52 cases (defined as flocks treated with antimicrobials when chickens were between 1 and 42 days old), were included. Another 208 controls (untreated flocks the same ages as the case flocks), were randomly selected and paired with a matching case (same farmer organization and placement date). On-farm questionnaires were administered. Multivariable logistic regression modeling was conducted; seven variables were significant in the final model. RESULTS: Two factors were associated with a lower probability of AMU: the use of chicken paper topped with starter feed (OR = 0.3; 95% CI = [0.1; 0.9]) and the use of herbal drugs as a prophylaxis (OR = 0.1; 95% CI = [0.01; 0.5]). A higher probability of AMU was associated with farmers perceiving the cumulative mortality of chicks between 1 and 10 days old as normal (OR = 10.1; 95% CI = [1.7; 59]) or high (OR = 58.7; 95% CI = [9.6; 372.3]). A higher probability of AMU also was associated with farmers detecting a health problem (OR = 12.5, 95% CI = [4.2; 36.9]) and phone calls between farmers and their technicians (OR = 5.9; 95% CI = [2.3; 14.8]) when chicks are between 11 to 42 days old. Two additional factors (litter thickness and cleaning/disinfecting) were significant and highlighted the importance of technical factors such as biosecurity. CONCLUSIONS: Our results suggest that to reduce AMU, technical training should be provided to farmers to improve how farms are monitored and to reinforce preventive health measures. Training also should address how farmers assess warning criteria like daily mortality rates, which when overestimated often lead to antimicrobial treatment.

Why do veterinarians ask for antimicrobial susceptibility testing? A qualitative study exploring determinants and evaluating the impact of antibiotic reduction policy.

For public health reasons, increasing attention has focused on more rational use of antimicrobials in farm animals. Guidance concerning the prescription of antibiotics and antimicrobial susceptibility testing (antibiograms in this case) are beneficial tools to help control the development of antimicrobial resistance. Nevertheless, even though there are already several qualitative studies analysing the determinants of antimicrobial prescription and use in veterinary medicine, little is known about decision-making concerning the use of antibiograms. The aim of this study was to provide a better understanding of veterinarians' motivations and role-players' influence concerning the choice of whether to ask for an antibiogram in the bovine, porcine, poultry and equine sectors in France. We concurrently evaluated the impact of a new French decree (2016) requiring an antibiogram before certain critically important antimicrobial agents can be used in veterinary medicine. Semi-structured interviews with veterinarians were conducted in France. Thematic analysis was used to analyse transcripts. In all, we surveyed 66 veterinarians. Use of antibiograms in veterinary medicine was multifactorial - 46 factors grouped into 11 categories were identified - and differed between animal sectors: use was almost systematic in poultry, frequent in pigs and rare in both the bovine and equine sectors. The decree has not increased the use of antibiograms but has induced a change in prescriptions due to field constraints and the time needed to obtain the results of antibiograms. Respondents see the decree as an aid in promoting responsible and rational use of antibiotics, fostering the use of alternatives. Our findings provide the basis of veterinarians' position regarding antibiogram use and antimicrobial resistance, pointing out levers to facilitate the use of antibiograms in veterinary medicine (for example communication on the benefits of this test and external financial support). Furthermore, the evaluation of the impact of the decree aimed at reducing the use of critically important antibiotic highlights key factors for a successful change in regulations, such as advance planning, precise and adapted communication, and demonstration of the measure's legitimacy. These results will be useful in guiding representative veterinary bodies and regulatory authorities during their decision-making, communication, and policy and regulation choices to combat antimicrobial resistance.