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

可在淡水、土壤、废水和牲畜中发现耐抗生素细菌。然而，目前尚不清楚这些耐药细菌在室外环境中传播给人类的容易程度。需要对自然环境中抗菌素耐药性（AMR）对人类健康的风险进行研究，并需要在环境中抗菌素耐药性水平高的地点和人类面临环境暴露高风险的地方进行研究。孟加拉国就是这样一个地方，许多因素有利于抗生素耐药性的传播，例如土壤和饮用水的广泛细菌污染；人口密度高；卫生设施不足、废水处理不当，以及经常发生的洪水和自然灾害。此外，廉价的抗生素很容易从非处方供应商处获得，导致在人类和动物中广泛使用。这项研究将检查在孟加拉国的室外环境中暴露于抗生素耐药性是否会对人类造成健康风险。这项研究的新颖之处在于，它将测量室外环境（淡水、土壤、废水）中耐药细菌的数量，并将其与同一时间、同一地点牲畜（家禽）和人类中耐药细菌的存在联系起来。这也将是首批测量高和低暴露于污染环境的人类抗菌素耐药性的研究之一。该研究将在三个地点进行，这些地点由于人类与AMR污染的动物和环境宿主相互作用，传播可能很高。这些地点是达喀市销售活禽的城市市场、商业家禽养殖场和家禽与人共用生活和睡眠区域的农村。我们将测量与家禽密切生活或工作的人（如活禽销售商和屠宰者、商业家禽养殖场工人和家中有家禽的农村妇女）肠道（粪便）中耐药细菌的数量。这些比率将与生活在类似环境但很少或没有接触家禽的人进行比较。我们预测，来自鸡肠道的耐药细菌将存在于家禽粪便中，这是通过密切接触将抗生素耐药性传播给人类的潜在途径。我们还预测，在家禽饲料中定期给予抗生素或作为药物的家禽中会有更多的抗菌素耐药性细菌，这将增加人类感染抗菌素耐药性细菌的风险。另一个目标是通过比较孟加拉国旱季和雨季的水、土壤和废物中的抗性基因数量，研究环境中的抗性细菌如何随时间变化。了解室外环境中抗菌素耐药性的季节性变化将使我们能够在抗菌素耐药性传播风险最高的时候采取有针对性的干预措施。最后，我们将研究畜牧业和家禽饲养中与使用抗生素作为药物和动物饲料有关的文化和社会实践。我们将观察农场工人、屠宰者和市场销售者的做法，以评估食品生产、销售和家禽废物处理的哪些方面会污染环境，以及哪些人类活动（洗手、使用手套、处理家禽）会增加或减少接触抗生素耐药性的风险。我们将利用这些信息确定减少抗微生物药物耐药性在动物和人类之间传播的方法。这项研究将为环境中的抗生素耐药性是否对人类健康构成严重威胁提供新的见解。随着新型耐药基因和细菌在南亚迅速传播，迫切需要确定抗菌素耐药性是如何通过水、土壤、废物和牲畜传播的，并确定可以采取哪些措施在全球范围内减少这种传播。

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.