Abstract

This study aimed to assess the contamination level of chicken litter by antibiotic residues and multidrug resistant (MDR) bacteria. A total of 28 chicken litter samples were aseptically collected in Abidjan poultry farms in December 2021. The bacteria including Salmonella, Escherichia coli and Staphyloccocus aureus were isolated on specific culture media and were identified using biochemical tests. Antibiotics susceptibility test of the isolates was performed by the disk diffusion method. Finally, the antibiotic residues were detected in litter samples by HPLC. Among the analyzed samples, 21 were positive for the three bacteria. Moreover, S. aureus isolates were resistant to tetracycline, clindamycine, trimethoprime, and erythromycine while E. coli and Salmonella strains were resistant to minocycline, nalidixic acid, and tetracycline with resistance rate above 75% for all strains. The MDR including 3 to 6 antibiotic classes were found in 90 and 23.07% of S. aureus and E. coli strains, respectively. Moreover, chicken litter samples were contaminated by antibiotic residues mainly ciprofloxacine, erythromycine, spiramycine and oxytétracycline with amounts between 0.05 ± 0.002 and 8.41 ± 2.03 mg/kg. These results showed the need to treat chicken litter before being used as fertilizer to reduce their negative impact on environment and health. 

Key words: Chicken litter, multidrug resistant bacteria, antibiotic residues, soil, crops pollution.