ABSTRACT
The use of animal manure to fertilize soil is an emerging concern contributing to the transfer of antimicrobial-resistant pathogens to vegetables. Hence, assessing antimicrobial susceptibility profile of Escherichia coli in vegetable farms is essential to design appropriate interventions against antimicrobial resistance (AMR) in the food chain. This study assessed antimicrobial resistance profile and associated genetic markers among E. coli isolated from vegetable farms fertilized with animal manure in Addis Ababa, Ethiopia. A total of 1044 samples were collected using convenience sampling: soil (n = 271), manure (n = 375), and vegetables (n = 398) from 81 vegetable farms in Addis Ababa, Ethiopia. Antimicrobial susceptibility test was conducted for 100 E. coli isolates and antimicrobial resistance genes (ARGs) were tested by polymerase chain reaction (PCR). Of the 1044 collected samples, 25.3% were positive for E. coli, with significantly higher prevalence in the manure sample and samples collected from Akaki Kality sub-city (p < .05). The highest resistance rate was recorded for tetracycline (72%), followed by streptomycin (63%), and sulfamethoxazole +trimethoprim (56%). Multidrug resistance was detected in 61% of the E. coli isolates. The aac(3)-IV (76.9%), bla TEM (65.4%), aadA (60.3%), tet(A) (58.3%), and sulI (51.7%) were the commonly detected resistance genes. The current study showed a high burden of antimicrobial resistance among E. coli isolated from manure-amended vegetable farms, with potential of playing a significant role in the dissemination of antimicrobial resistance in the food chain. Efforts should be made to reduce the burden of resistant organisms and ARGs through prudent use of antimicrobials in livestock and application of appropriate composting techniques before using manure as fertilizer.
ABSTRACT
Foodborne pathogens significantly impact public health globally. Excessive antimicrobial use plays a significant role in the development of the public health crisis of antibiotic resistance. Here, we determined the prevalence and antimicrobial resistance profiles of E. coli O157, Salmonella, L. monocytogenes, and Campylobacter isolated between 2016 and 2020 from small scale agricultural settings that were amended with dairy cattle or poultry manure in Northeastern Ohio. The total prevalence of the foodborne pathogens was 19.3%: Campylobacter 8%, Listeria monocytogenes 7.9%, Escherichia coli O157 1.8%, and Salmonella 1.5%. The prevalence was significantly higher in dairy cattle (87.7%) compared to poultry (12.2%) manure amended farms. Furthermore, the prevalence was higher in manure samples (84%) compared to soil samples (15.9%; p < 0.05). Multiple drug resistance was observed in 73%, 77%, 100%, and 57.3% of E. coli O157, Salmonella, L. monocytogenes, and Campylobacter isolates recovered, respectively. The most frequently observed resistance genes were mphA, aadA, and aphA1 in E. coli O157; blaTEM, tet(B), and strA in Salmonella; penA, ampC, lde, ermB, tet(O), and aadB in L. monocytogenes and blaOXA-61, tet(O), and aadE in Campylobacter. Our results highlight the critical need to address the dissemination of foodborne pathogens and antibiotic resistance in agricultural settings.
