Spatial and temporal dynamics of AMR transmission from the outdoor environment to humans in urban and rural Bangladesh

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Antibiotic resistant bacteria can be found in freshwater, soil, wastewater and among livestock. It is not yet known, however, how easily these resistant bacteria in the outdoor environment can be transmitted to humans. Research is needed on the human health risk from antimicrobial resistance (AMR) in the natural environment, and research is required in locations with high levels of AMR in the environment and where humans are at high risk of environmental exposure. Bangladesh is one such location where many factors favour the transmission of antibiotic resistance such as the widespread bacterial contamination of soil and drinking water; high human population densities; inadequate sanitation and poor treatment of wastewater alongside regular floods and natural disasters. Furthermore, inexpensive antibiotics are readily available from over-the-counter suppliers leading to widespread use in humans and animals. This study will examine whether there is a health risk to humans from being exposed to AMR in the outdoor environment in Bangladesh. The novelty of the study is that it will measure the quantity of resistant bacteria in the outdoor environment (freshwater, soil, wastewater) and relate this to the presence of resistant bacteria in livestock (poultry) and humans at the same time and in the same locations. This will also be one of the first studies to measure AMR in humans with high and low exposure to contaminated environments. The study will take place in three locations where transmission is likely to be high because of human interaction with animal and environmental reservoirs of AMR contamination. These locations are urban markets selling live poultry in Dhaka city, commercial poultry farms and rural villages where poultry and humans share living and sleeping areas. We will measure the quantity of resistant bacteria in the gut (faeces) of humans who live or work closely with poultry (such as live poultry sellers and slaughterers, commercial poultry farm workers and village women who have poultry living in the household). These rates will be compared to humans who share similar environments but have little or no exposure to poultry. We predict that the resistant bacteria from the gut of chickens will be present in poultry faeces and that this is a potential route of AMR transmission to humans through close contact. We also predict that there will be more AMR bacteria in poultry that are given antibiotics regularly in poultry feed or as medication and this will increase the risk of AMR bacteria in humans. A further aim is to study how resistant bacteria in the environment change over time by comparing the quantity of resistant genes in water, soil and waste during the dry season and wet season in Bangladesh. Understanding the seasonal changes of AMR in the outdoor environment will enable us to target interventions at times when the risks of transmission of AMR are highest.Finally, we will examine the cultural and social practices in animal husbandry and poultry keeping in relation to the use of antibiotics as medicine and in animal feed. We will observe the practices of farm workers, slaughterers and market sellers to assess which aspects of food production, selling and disposal of poultry waste contaminate the environment, and what human activities (hand washing, use of gloves, handling of poultry) increase or decrease risk of exposure to AMR. We will use this information to identify ways of reducing the spread of AMR among animals and humans. This study will provide new insight into whether AMR in the environment is a serious threat to human health. As new forms of resistant genes and bacteria are spreading rapidly in south Asia, there is an urgent need to establish how AMR can be transmitted through water, soil, waste and livestock, and identify what can be done to reduce this transmission at a global level.