Antimicrobial resistance occurs when microorganisms evolve to develop mechanisms to protect themselves from the effects of antimicrobial drugs, i.e., they become resistant to these drugs used to treat infections. Antibiotic resistance is a subset of antimicrobial resistance which applies specifically to bacteria that become resistant to antibiotics. Antifungal, antiviral and antiprotozoal resistance are other types of antimicrobial resistance. Resistance to pesticides is seen in agriculture. The resistance can occur through genetic mutation or by spreading of resistant genes from one organism to another.
Antibiotic resistance is mainly caused by the overuse and inappropriate use of antibiotics. When microorganisms develop antibiotic resistance, common infections become much harder, and sometimes impossible, to treat. Antibiotic resistance is increasing globally and is considered by the World Health Organisation to be one of the top global public health and development threats, being directly responsible for 1.27 million deaths in 2019 and contributing to a further 4.95 million deaths.
Antimicrobial resistance can spread through water, the environment, waste materials, animal feed, food, animals and humans. Antimicrobial resistance is thus not only one of the greatest global threats to human health, but also to the health of animals, plants and ecosystems. Since antimicrobial resistance moves across these different industries and populations, a ‘One Health’ approach to solving antimicrobial resistance, considering agricultural, the environment and human health sectors, is required. One Health is an integrated approach with the goal to sustainably balance and optimise the health of people, animals and ecosystems.1 The World Health Organisation has recently published “A One Health Priority Research Agenda for Antimicrobial Resistance” to advocate for and promote research and investment in response to antimicrobial resistance.2
Wastewater is a pathway for spread of antimicrobial resistance. Municipal wastewater contains trace concentrations of antimicrobial drugs (e.g. from excretion of remaining antibiotic dose administered in humans), their metabolites (compounds produced in the body from the original drug) and/or transformation products (compounds produced in the wastewater system from the original drug and/or its metabolites), as well as microorganisms excreted from humans some of which may show antimicrobial resistance. Wastewater treatment plants generally employ physical, chemical and biological processes, with the key goal to remove pathogenic microorganisms, nutrients and organic matter from the water stream. Wastewater treatment plants are not designed for removal of antimicrobial drugs, or antimicrobial resistant organisms or genes, and, hence, removal of these chemicals and microorganisms can be incomplete. In addition, the biological processes in wastewater treatment involve microorganisms using wastewater components as a food source to grow. These microorganisms are also exposed to low concentrations (sub-inhibitory) of antimicrobial drugs and antimicrobial resistant organisms in wastewater and can develop and spread antimicrobial resistance and antimicrobial resistant genes.
Two product streams are generated during wastewater treatment, i.e. treated wastewater and wastewater sludge. Removal of antimicrobial drugs and antimicrobial resistant genes from the wastewater often involves their adsorption onto the sludge. Some wastewater sludge is disposed of in landfill. Some wastewater sludge is further treated into a product known as biosolids, which can then be applied to agricultural land as a fertilizer and soil conditioner. Both pathways have the potential to release trace, residual concentrations of antimicrobial drugs and antimicrobial resistant genes into the environment. To fully understand the risk of municipal wastewater as a pathway to distribution of antimicrobial resistance in the environment, it is important to investigate the fate of antimicrobial drugs and antimicrobial resistant genes in wastewater sludge and its receiving environments.
1 One Health High-Level Expert Panel, Adisasmito WB, Almuhairi S, Behravesh CB, Bilivogui P, Bukachi SA et al. One Health: a new definition for a sustainable and healthy future. PLOS Pathog. 2022;18:e1010537. doi: 10.1371/journal.ppat.1010537.
2 A One Health Priority Research Agenda for Antimicrobial Resistance, World Health Organisation, Food and Agriculture Organisation of the United Nations, United Nations Environment Programme and World Organisation for Animal Health, 2023, https://iris.who.int/bitstream/handle/10665/370279/9789240075924-eng.pdf?sequence=1
Aim
The aim of this project is to investigate the fate of selected antibiotics and antimicrobial resistance genes in wastewater treatment in terms of their adsorption to wastewater sludge and their persistence in wastewater biosolids. The resultant risk of distribution of antimicrobial resistance in the environment will be assessed. Additional support for this project will be sought through CRC SAAFE (Cooperative Research Centre for Solving Antimicrobial Resistance in Agribusiness, Food and Environments) and partners in the water industry.
Objectives
Objective 1: Antibiotics and antimicrobial resistance inducing chemicals for study will be prioritised after a review of the literature and in consultation with CRC SAAFE and industry.
Objective 2: The second stage of this project will involve development of an analytical method for the selected antibiotics and antimicrobial resistance inducing chemicals in wastewater, sludge and biosolids, using liquid chromatography-mass spectrometry (LC-MS) or gas chromatography-mass spectrometry. Extraction of the analytes from the sludge and biosolids will be a key aspect of this stage.
Objective 3: In collaboration with the water industry, wastewater, sludge and biosolids samples from 2-3 wastewater treatment plants will be collected. Monthly samples will be collected over a 12 month period. Samples will also be analysed for antimicrobial resistant genes through a collaborative arrangement.
Objective 4: Laboratory studies investigating changes occurring during conversion of sludge to biosolids and the potential of the analytes to leach from the sludge and biosolids products will be conducted.
Objective 5: The environmental risk of antibiotics and antimicrobial resistance inducing chemicals in sludge and biosolids products will be assessed.
Significance
Increasing levels of antimicrobial resistance will hinder progress towards many of the United Nations Sustainable Development Goals (UN SDGs), particularly SDGs 1, 2, 3, 6, 8 and 11. Hence, a One Health solution approach to antimicrobial resistance is crucial to achieving the UN SDGs by 2030. This project directly addresses UN SDG 6 (Clean Water and Sanitation) and 11 (Sustainable Cities and Communities). This project will contribute to addressing the World Health Organisation’s One Health priority research agenda for antimicrobial resistance, the Australian National Antimicrobial Resistance Strategy for 2020 and Beyond3 and its One Health Master Action Plan.4 In addition, this project will likely contribute to the Water Consortium Monitoring Project within the CRC SAAFE, of which Curtin is a research member organisation.
3 Australia’s National Antimicrobial Resistance Strategy: 2020 & Beyond, Australian Government Department of Health and Department of Agriculture, Water and the Environment, 2019, https://www.amr.gov.au/sites/default/files/2022-11/australia-s-national-antimicrobial-resistance-strategy-2020-and-beyond_0.pdf
4 One Health Master Action Plan, Australian Government Department of Health and Department of Agriculture, Water and the Environment, 2021, https://www.amr.gov.au/sites/default/files/2022-10/one-health-master-action-plan-for-australia-s-national-antimicrobial-resistance-strategy-2020-and-beyond.pdf
Ideal Candidate
We are looking for a self-motivated PhD candidate with excellent organisation, problem-solving and project management skills. Ideally a Chemistry Honours graduate with skills in analytical chemistry and organic chemistry and an interest in sustainability and application of chemistry to real-world systems. Strong written and oral English communication skills are essential. Additionally, the applicants should meet the eligibility criteria for entry into a PhD program at Curtin University.
This project is open to Domestic applicants only.
Internship
Through this project you will also have an internship opportunity. More information will be provided at a later date.
Scholarship
If you are identified as the preferred candidate for this project, you may be considered for an RTP scholarship.
Enquires and How to Apply
For enquires about this opportunity contact Professor Cynthia Joll at C.Joll@curtin.edu.au
To formally apply submit an Expression of Interest to Professor Cynthia Joll during the Central Scholarship round (July 1st – July 31st 2026)