Mapping the evidence of the effects of environmental factors on the prevalence of antibiotic resistance in the non-built environment

The is a comprehensive systematic evidence map on the evidence of the effects of environmental factors on the prevalence of antibiotic resistance in the non-built environment. We researched 13,000 studies from 1990 to 2021 to identify patterns and gaps in the topic area. We identified 738 studies that focused strictly on non-built, non-industrial environments, such as rivers, fields and air. 

We found that antibiotic-resistant bacteria are most often detected in freshwater and soil, particularly in places exposed to pollution from wastewater or manure. Two bacteria - Escherichia coli and Pseudomonas - were the most studied organisms, while genes conferring resistance to medicines including sulphonamides, tetracyclines and beta-lactams, were very prominent.  Very few studies have explored how antibiotic resistance spreads in the air, oceans or green spaces.  we also noticed a lack of research in low-income regions, where the health burden of antibiotic resistance is likely to be highest.  We also found that a third of the studies came from China, followed by the United States. But fewer than one percent were led by researchers in low-income countries, such as Afghanistan, Ethiopia, Mali and Uganda, despite these areas facing some of the greatest health risks from antibiotic resistance. Climate change and microplastics were also strikingly absent from the evidence base. While this trend may have shifted in last couple of years, given the rapid evolution of the field, it is unlikely to have changed substantially, leaving critical questions unanswered about how environmental shifts may be accelerating the problem.  

Antibiotic resistance increasingly threatens the interconnected health of humans, animals, and the environment. While misuse of antibiotics is a known driver, environmental factors also play a critical role. A balanced One Health approach—including the environmental sector—is necessary to understand the emergence and spread of resistance.

We systematically searched English-language literature (1990–2021) in MEDLINE, Embase, and Web of Science, plus grey literature. Titles, abstracts, and keywords were screened, followed by full-text reviews using a structured codebook and dual-reviewer assessments.

Of 13,667 records screened, 738 met the inclusion criteria. Most studies focused on freshwater and terrestrial environments, particularly associated with wastewater or manure sources. Evidence of research has predominantly focused on Escherichia coli and Pseudomonas spp., with a concentration on ARGs conferring resistance to sulphonamides (sul1–3), tetracyclines (tet), and beta-lactams. Additionally, the People’s Republic of China has produced a third of the studies—twice that of the next country, the United States—and research was largely domestic, with closely linked author networks.

Significant evidence gaps persist in understanding antibiotic resistance in non-built environments, particularly in marine, atmospheric, and non-agricultural settings. Stressors such as climate change and microplastics remain notably under-explored. There is also an urgent need for more research in low-income regions, which face higher risks of antibiotic resistance, to support the development of targeted, evidence-based interventions.