Antimicrobial susceptibility profile of members of Gammaproteobacteria in vegetable value chains of central part of Ethiopia

Abstract Background Antimicrobial-resistant bacteria originating from vegetable farms represent a growing global concern with serious public health implications. Continuous assessment, surveillance, and monitoring of antimicrobial resistance along the farm-to-consumer pathway are therefore essential. This study aimed to assess the antimicrobial susceptibility profiles of selected bacterial species belonging to the Gammaproteobacteria, isolated from irrigation water, soil, farms, and supermarket vegetables. Methods A cross-sectional study was conducted in central Ethiopia from February to June 2024. A total of 408 samples (soil, irrigation water, vegetable from farms and supermarkets) were collected from six formal vegetable farms and supermarkets in central Ethiopia. Identification was performed using conventional biochemical tests and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). All isolates were tested for their susceptibility to 16 antimicrobials following Clinical laboratory standards institute (CLSI) guidelines using Kirby Bauer disk diffusion assay. Chi-square test was used to assess difference of antimicrobial resistance among bacteria isolates between sampling types, with a p -value of less than 0.05 considered statistically significant. A multivariable binary logistic regression analysis was employed to identify factors associated with multidrug resistance (MDR), with sampling types and genus. Results Out of the total (331) isolates, the dominant species identified were Escherichia coli and Enterobacter spp., followed by Citrobacter spp. The proportion of bacterial genera was highest in vegetable samples from farms (32.3%), followed by vegetables obtained from supermarkets (18.6%), soil (16.4%), and irrigation water (14.2%). The highest resistance rate (40%) was observed in E. coli isolates from supermarket vegetables to ampicillin and piperacillin/tazobactam, while highest rate of resistance to ceftazidime was observed among Enterobacter spp. from irrigation water (37.5%). Overall, 33.2% of isolates were susceptible to all antimicrobials, 24.7% were resistant to at least one antibiotic, and 20.8% were multidrug resistant (MDR). MDR occurrence was highest in vegetables isolates (26.4%), followed by soil (19.4%) and irrigation water (19%). The highest MDR prevalence was observed in Klebsiella oxytoca (60%), followed by Klebsiella aerogenes (33.3%). Conclusion The current study highlights the presence of multidrug resistant environmental bacteria, including Enterobacteriaceae family and Acinetobacter spp. throughout vegetable production from farms to supermarkets. The presence of MDR environmental isolated Enterobacteriaceae family and Acinetobacter spp. throughout vegetable production and supermarkets emphasizes the importance of increased surveillance of antimicrobial resistance (AMR) in fresh produce and the production environment within a One Health paradigm to develop AMR control strategies.