Antibiotics in poultry manure and their associated health issues: a systematic review

Purpose Antibiotics are growing environmental contaminants leading to public health concern. Antibiotics are commonly used as growth promoters and therapeutic agents in poultry feed that are not completely metabolized in the body tissues of chicken, get deposited in meat as parent compounds, and ultimately excreted via poultry droppings into the environment. These antibiotics in the soil result into the creation of antibiotic resistance in bacteria via activation of antibiotic resistance genes (ARGs). The development of ARGs and antibiotic-resistant bacteria (ARB) lead to huge physical and economic losses, as these bacteria cannot be treated with commonly used antibiotics. Moreover, these antibiotics after entering into food chains seriously affect the human immune system, growth, and metabolism of the body. Therefore, to reduce the future health risks of antibiotics, there is a dire need to understand the fate of poultry antibiotics and spread of ARGs in the soil environment. Materials and methods In this manuscript, we reviewed the existing literature about the antibiotics used in the poultry sector, soil contamination through application of poultry manures, and development of ARB in environment. An attempt has been done to present a better understanding of emerging contaminants (ARGs, ARB) in the soil environment and their associated human health effects. Results and discussion In this paper, we summarized the use of antibiotics in the poultry sector, persistence of antibiotics in animal body, and their release into environment. Transfer mechanism of antibiotics and their metabolites to the human body and their fatal effects have been investigated. Developments of ARB and ARGs in the soil due to excessive use of veterinary antibiotics have been highlighted. Conclusions Poultry antibiotics are causing human health risks by development of ARGs and ARB. Such antibiotic resistance cannot be treated with common antibiotics. Therefore, effective measures are needed to control this emerging problem by improving the efficiency of antibiotics, reducing the spread of resistance genes, and proper monitoring of antibiotics in poultry feed and manure. Manure composting and biochar application are the possible ways to reduce the risk and spread of ARGs in environment due to manure application in agriculture field. The pathways that allow antibiotic, ARGs, and ARB to move through the environment are not fully understood and there is a need for further research to make clear the reservoirs and routes of antibiotic-related contaminants in the ecosystem.