ENVIRONMENTAL RESERVOIRS AND DISSEMINATION PATHWAYS OF ANTIMICROBIAL RESISTANCE GENES IN AFRICA: A PRISMA-SCR SCOPING REVIEW

Antimicrobial resistance (AMR) is a priority global health threat. Environmental compartments including wastewater, surface water, soils, and sediments act as important reservoirs for antimicrobial resistance genes (ARGs) and are critical in sustaining and amplifying resistance beyond clinical settings. In Africa, structural factors such as rapid urbanisation, inadequate sanitation infrastructure, unregulated antibiotic use in livestock, and high infectious disease burdens may intensify environmental AMR pressures. Despite this, no comprehensive synthesis of the environmental ARG evidence base across Africa has been undertaken. This scoping review aimed to map the extent, range, and nature of evidence on environmental ARGs across Africa, including the types of reservoirs studied, the ARGs detected, the geographic distribution of research, and the dissemination pathways described. We conducted a scoping review following Joanna Briggs Institute (JBI) methodology and reported in accordance with the PRISMA Extension for Scoping Reviews (PRISMA-ScR) checklist. Six electronic databases (PubMed, Scopus, Web of Science, EMBASE, Google Scholar, African Journals Online) were searched from January 2010 to December 2026. Eligible studies were conducted in African countries, analysed environmental samples (water, wastewater, soil, sediment, manure, aquaculture, or wildlife matrices), and reported molecular detection of ARGs by PCR, qPCR, or sequencing approaches. No quality-based exclusions were applied. Data were extracted using a standardised template and synthesised narratively. Seventy-three studies from 18 African countries met inclusion criteria. Nigeria (n=28, 38%) and South Africa (n=15, 21%) together accounted for 59% of all studies. Wastewater systems were the most studied reservoir (49%), followed by hospital effluents (22%) and surface water (18%). Forty-seven distinct ARGs were identified across all studies; the most frequent were blaCTX-M (58%), sul1 (48%), tetA (44%), and blaTEM (41%). Carbapenemase genes were detected in 11 studies (15%), all from hospital effluent or wastewater. Conventional PCR was used in 74% of studies; no study employed shotgun metagenomics. Only 40% of studies explicitly discussed dissemination pathways, predominantly untreated wastewater discharge and agricultural runoff. No study was identified from Central Africa. Environmental ARG evidence from Africa is geographically concentrated, methodologically constrained by reliance on targeted PCR, and heavily focused on wastewater and hospital effluent matrices. Major gaps persist for Central and West Africa (excluding Nigeria), soil and wildlife reservoirs, and metagenomic characterisation of the environmental resistome. Standardised, multi-compartment, One Health surveillance — combined with investment in metagenomic capacity and evidence-based wastewater interventions — is urgently needed.