Occurrence and Antimicrobial Resistance Profiles of Bacteria from Dairy Farm Environments in Addis Ababa, Ethiopia

Background Wastes generated from dairy environments are critical hotspots where pathogenic and opportunistic pathogens interact with high concentrations of antibiotic residues and normal flora, potentially contributing to the occurrence of superbugs. Therefore, this study aimed to isolate bacteria from dairy environmental feces, manure, and waste effluent, determine their antimicrobial resistance patterns, and examine the distribution of extended-spectrum beta-lactamase and carbapenemase-producing bacterial isolates in Addis Ababa, Ethiopia. Methods A cross-sectional study was conducted in Addis Ababa, Ethiopia, from June 2023 to November 2024. A total of 88 samples, including feces, manure, and wastewater effluent, were collected from the dairy farm environment. The samples were transported and processed under sterile conditions. Following this, bacterial isolation, identification, and antimicrobial susceptibility testing were performed in accordance with standard microbiological protocols. Results Out of the total samples collected, 137 bacterial isolates were recovered from the dairy farm environment, with the highest proportion, 76(50.7%), found in fecal samples. Enterobacter spp. (28, 20.4%) and E. coli (20, 13.3%) were the most frequently isolated species among the bacterial isolates. E. coli showed the highest percentage of multidrug resistance, 12 (60%), among the tested isolates. Overall, 45.3% of the bacterial isolates were ESKAPE pathogens. Of these, 53 (85.5%) were gram-negative bacteria, while 9 (14.5%) were gram-positive bacteria. Gram-positive bacteria had the highest resistance rates against penicillin (12, 52.2%) and tetracycline (11, 47.8%), whereas Gram-negative bacteria showed the highest resistance against ampicillin (68, 73.9%). Multidrug resistance was present in 46% of the bacterial isolates. Conclusion Wastes generated from dairy farm environments contain multidrug-resistant bacterial isolates, which may contaminate nearby environments, crops, and water bodies and affect public health. Therefore, there must be proper antibiotic usage in dairy farm settings and adequate management of dairy manure and wastewater effluent before they are discharged into the environment.