Associations between antimicrobial use and antimicrobial resistance of Escherichia coli isolated from poultry litter under field conditions in Cameroon.

Lack of hygiene and biosecurity measures in poultry farms has influence on the emergence of pathogens and antimicrobial use. Antimicrobial residues in poultry meat and their excretion by poultry can exert a selective pressure and the occurrence of multidrug resistant bacteria in litter. The objective of this study was to investigate the relationship between antimicrobial use and antimicrobial resistance using Escherichia coli as indicator isolated from poultry litter. From January to August, 2019, antimicrobial use was measured in 47 broiler farms based on daily dose (TI) and animal daily dose (TI) methods. Antimicrobial susceptibility testing was performed on Escherichia coli isolated from poultry litter using the disk diffusion method. Overall, an average of 143.8 mg (ranging from 0.5 to 2061.79 mg/kg) of antimicrobials was used per kg of chicken produced, and treatment incidences of 69.7 daily doses per 1,000 broilers (44.44-106.35) and 87.3 daily doses per 1,000 broilers (1.74-376.43) were obtained for TI and TI, respectively. After a susceptibility testing, 18 E. coli strains were resistant with a prevalence of 56.3% [95% CI: 39.1-73.5]. High levels of resistance were observed with doxycycline, ampicillin and norfloxacin which were observed to be mostly overdosed in farms. The high resistance of E. coli to ciprofloxacin (4/32: 13%), imipenem (6/32: 19%), levofloxacin (12/32: 38%) and ceftriaxone (22/32: 69%) which are second line treatment in hospital settings in Cameroon, and classified as Watch group by WHO, was associated to high AMR risk for public health in Cameroon. Intensification of health and educational sensitisation of farmers is essential to reduce widespread antimicrobial use in poultry farms and its impact public health.