BackgroundThe role of the crop environment as a conduit for antimicrobial resistance (AMR) through soil, water, and plants has received less attention than other sectors. Food crops may provide a link between the agro-environmental reservoir of AMR and acquisition by humans, adding to existing food safety hazards associated with microbial contamination of food crops.ObjectivesThe objectives of this review were: (1) to use a systematic methodology to characterize AMR in food crop value chains globally, and (2) to identify knowledge gaps in understanding exposure risks to humans.MethodsFour bibliographic databases were searched using synonyms of AMR in food crop value chains. Following two-stage screening, phenotypic results were extracted and categorized into primary and secondary combinations of acquired resistance in microbes of concern based on established prioritization. Occurrence of these pathogen-AMR phenotype combinations were summarized by sample group, value chain stage, and world region. Sub-analyses on antimicrobial resistance genes (ARG) focused on extended-spectrum beta-lactamase and tetracycline resistance genes.ResultsScreening of 4,455 citations yielded 196 studies originating from 49 countries, predominantly in Asia (89 studies) and Africa (38). Observations of pathogen-phenotype combinations of interest were reported in a subset of 133 studies (68%). Primary combinations, which include resistance to antimicrobials of critical importance to human medicine varied from 3% (carbapenem resistance) to 13% (fluoroquinolones), whereas secondary combinations, which include resistance to antimicrobials also used in agriculture ranged from 14% (aminoglycoside resistance) to 20% (aminopenicillins). Salad crops, vegetables, and culinary herbs were the most sampled crops with almost twice as many studies testing post-harvest samples. Sub-analysis of ARG found similar patterns corresponding to phenotypic results.DiscussionThese results suggest that acquired AMR in opportunistic and obligate human pathogens is disseminated throughout food crop value chains in multiple world regions. However, few longitudinal studies exist and substantial heterogeneity in sampling methods currently limit quantification of exposure risks to consumers. This review highlights the need to include agriculturally-derived AMR in monitoring food safety risks from plant-based foods, and the challenges facing its surveillance.

Background One Health (OH) has resurfaced in the light of the ravaging COVID-19 pandemic. It has been accepted by many local and global health authorities as a suitable approach for preventing and responding to infectious disease outbreaks including pandemics. Main body One Health (OH) is a multisectoral and interdisciplinary framework for managing the animal, human, and ecosystem determinants of health. Globally, the majority of emerging infections in humans including SARS-Cov2—the causative agent of COVID-19—are transmitted from animals through environmental contacts in the last few decades. Yet, even when the biological and social interactions at the human, animal, and environmental interface that drive spillover of zoonotic diseases have been proven, OH strategies to address associated complex health challenges today are still rudimentary in many national health systems. Despite the disproportionate burden of infectious diseases in sub-Saharan Africa, OH is minimally incorporated into routine disease control and national health security programs. Challenges include poor policy support for OH in sub-Saharan Africa, and where some form of policy framework does exist, there are significant implementation bottlenecks. In this paper, we identified ideological, technical, operational, and economic barriers to OH implementation in Nigeria and sub-Saharan Africa, and highlighted possible recommendations across these domains. In order to yield sustainable benefits, a relevant OH policy approach in the sub-Saharan African health systems must derive from a buy-in of the critical mass of stakeholders in the society. Conclusion The implementation of sustainable OH approaches as a countermeasure to recurring emerging infections is a developmental priority for sub-Saharan African countries. A deep understanding of the local context must be leveraged to develop integrative OH solutions that are bold, rooted in science, and proven to be compatible with the level of development in sub-Saharan Africa.

Application of human and animal waste to fields and water sources and on-farm antimicrobial usage are documented contributors to the occurrence of antimicrobial resistance (AMR) in agricultural domains. This meta-analysis aimed to determine the prevalence of resistance to tetracycline (TET) and third generation cephalosporins (3GC) in Enterobacteriaceae isolated from food crops. TET was selected in view of its wide use in agriculture, whereas 3GC were selected because of the public health concerns of reported resistance to these critically important antibiotics in the environment. Forty-two studies from all six world regions published between 2010 and 2022 met the eligibility criteria. A random effects model estimated that 4.63% (95% CI: 2.57%, 7.18%; p-value: <0.0001) and 3.75% (95%CI: 2.13%, 5.74%; p-value: <0.0001) of surveyed food crops harboured Enterobacteriaceae resistant to TET and 3GC, respectively. No significant differences were observed between pre- and post-harvest stages of the value chain. 3GC resistance prevalence estimates in food crops were highest for the African region (6.59%; 95% CI: 2.41%, 12.40%; p-value: <0.0001) and lowest for Europe (1.84%; 95% CI: 0.00%, 6.02%; p-value: <0.0001). Considering the rare use of 3GC in agriculture, these results support its inclusion for AMR surveillance in food crops. Integrating food crops into One Health AMR surveillance using harmonized sampling methods could confirm trends highlighted here.