Abstract / Summary
Antimicrobial resistance (AMR), primarily caused by irrational antimicrobial use in humans, animals, and agriculture, poses a serious global public health threat, particularly in resource-limited low- and middle-income countries, where milk processing, hygiene standards, and prudent antimicrobial use regulations are minimal. Previous studies in Ethiopia reported the prevalence of AMR in Escherichia coli bacteria in milk and dairy environments but have overlooked the relationships to milk consumers. This study aimed to investigate AMR patterns in E. coli isolated from milk, the milking environment, and milk consumers in Addis Ababa milksheds in Ethiopia. A cross-sectional study design was used to collect 404 samples from proportional simple randomly selected milksheds in Addis Ababa, from which raw bulk milk, stool from milk consumers, and milking-environment samples were collected. E. coli was isolated and identified using standard bacteriological protocols and confirmed by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS). Isolates were tested for antimicrobial susceptibility against twelve antimicrobials from eight antimicrobial classes using the Kirby-Bauer disk diffusion method on Mueller-Hinton agar, following the guidelines of the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Multidrug resistance (MDR) and multiple antimicrobial resistance indices (MARI) were calculated, and analyses were performed using R. Presumptive E. coli was isolated from 18.6% and confirmed in 12.6% of the 404 samples analyzed. Overall, 84.3% of isolates were resistant to at least one antimicrobial tested, with the highest resistance rates for gentamicin (64.7%), ampicillin (52.9%), and tetracycline (41.2%), while resistance to ceftazidime (5.9%) and cefotaxime (7.8%) were low. MDR was observed in 50.9% of the isolates, with MARI values ranging from 0.17 to 1. The study revealed a low detection rate of E. coli but a considerably high proportion of AMR in Addis Ababa milksheds, Ethiopia. The finding underscores the need for targeted One Health surveillance to curb the emergence and simultaneous occurrences of antimicrobial-resistant E. coli at dairy production interfaces and safeguard public health.