A guest post by Elizabeth Holton, University of Bath
The discovery of antibiotics unquestionably changed the face of public health. However, pathogenic tolerance to these drugs is ever increasing, and it’s becoming a global concern. The topic of antimicrobial, or antibiotic resistance (AMR) has existed for almost as long as the initial discovery of penicillin in the late 1920s; the difference now is the lack of new drugs being developed as alternatives. The discovery of new antibiotics is of course critical, yet we should be focusing more attention on prevention and containment. Inappropriate usage and disposal, livestock supplements in agriculture, and poor international regulation are some significant contributors; but are often difficult to quantify. One technique that is now being utilized is ‘water fingerprinting.’
Water fingerprinting, which originated from wastewater-based epidemiology, is the monitoring of biological or chemical indicators to assess the public health of a community. Rather than relying on the collection of samples from individual volunteers or patients, researchers take samples from a wastewater treatment plant that represents an entire catchment population. This method has recently reached the public eye as a novel technique for monitoring localized outbreaks of COVID-19; although it has been well established within drug surveillance research for several years.
In terms of the AMR crisis, water fingerprinting can be used to determine the concentration of antibiotics reaching and persisting in the environment, as well as calculating community usage. Different antibiotics work in different ways within the body – some break down or change form, and others are eliminated from the body unchanged. Therefore, it is important to quantify the various human metabolites in order to more accurately calculate the usage. Most countries do not have accessible prescription databases with inherent ease of use. Even if the desired data is open source, it is rarely collated and standardized between pharmacies and hospitals, private and public sectors. However, much of this information can be determined independently, via studying wastewater. Incorporating parameters, such as water flow rates and population estimates with the concentration of antibiotics measured in the treatment plant, can help calculate usage per day and per capita.
Here, observations can be made such as weekly or seasonal trends, relative prescribing between communities, or significant changes in usage that might indicate an outbreak of infectious disease. Usage of antibiotics can also be correlated with the prevalence of resistance genes. The monitoring of this relationship can determine the significance of environmental pollution on the propagation of AMR.
Antibiotic quantities in wastewater are indicative of public health, however it is also important to consider the impact of antibiotics in terms of environmental health. Most pharmaceuticals do not degrade easily, and they eventually end up in our waterways. Even those that do break-down leave behind products that can also be detrimental to the ecosystem. Tolerance to antibiotics can be acquired by microbes when exposed to small quantities of the drug and its breakdown products over time. This idea of a ‘selective pressure’ may lead to microbes with stronger natural defenses, and as a result, greater survival and reproduction success. Therefore, even at low levels, antibiotic pollution can contribute to the dissemination of AMR. Consequently, water fingerprinting techniques are also applied to monitor river systems in and around urban areas.
A research initiative, ReNEW, was formed as a collaboration between the University of Bath, UK and Stellenbosch University, South Africa. The team is a collective of several disciplines, involving engineering, natural and social sciences. Alongside the objective to develop public health early-warning systems, the research also aims to contribute towards our understanding of AMR cause and effect.
The location for this research initiative was selected due to the existing relationship between the partner universities, as well as the characteristics of Stellenbosch town itself. Stellenbosch was an ideal case study location due to its diverse infrastructure, comprising both established housing and informal settlements. The latter communities are not connected to sewer lines; therefore, wastewater that is discarded within the settlement subsequently joins the river systems as land run-off. When areas experience rapid urbanization and population increase, the health of the community can become more at risk. Disease spread is harder to control in densely populated areas, particularly if infrastructure is not adequate. Limited access to clean water, improper sanitation, removal of waste, and limited or improper use of pharmaceuticals can all facilitate the spread of disease.
Ten sampling sites were determined, including the wastewater treatment plant that serves the town, and incorporating the three river systems that pass through it. Over five-hundred samples, in duplicate, were collected over a 12-month period and examined using several analytical techniques, including antibiotic quantitation. Data from chemical analyses (drug quantities), biological analyses (gene presence), and civil engineering (hydraulic modeling) were utilized to establish correlations and relationships. We are hoping this longitudinal case study will enhance the profile of water fingerprinting, particularly regarding the combination of data from multiple research disciplines.
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