Potential Threat: Antimicrobials


For the most part, antibiotics play a positive role in the modern world. They help combat infection and keep us healthy. However, antibiotics often find their way into water streams and wastewater treatment plants while still biologically active. And that’s a problem for a variety of reasons.

First off, the presence of antimicrobials creates potential for direct human health effects through ingestion. But perhaps more alarmingly, these substances can change the microorganisms in the water through the development of antibiotic resistance genes and bacteria. These changes can reduce the therapeutic potential of antibiotics against both human and animal pathogens.

Antimicrobial resistance is a worldwide public health emergency. The World Health Organization has ranked antimicrobial resistance as a “major threat to human health.” And the UK’s Review on Antimicrobial Resistance estimates that if appropriate action is not taken, by the year 2050, 10 million deaths each year will be due to antimicrobial-resistant organisms at a global economic cost of $100 trillion USD.

Wastewater treatment plants are interfaces between different environments and, therefore, provide an opportunity for pathogens, antimicrobials, and bacteria to mix—a comingling that may have future consequences.

Research regarding the spread of antimicrobial resistance in wastewater environments is conflicting, however. Some studies report that current wastewater treatment practices reduce the proportion of antimicrobial-resistant bacteria, while others suggest that the treatment process may actually increase it.

As an example, a 2016 study by Proia et al. demonstrated that the total number of antimicrobial-resistant E. coli was reduced by wastewater treatment but indicated that, in general, wastewater effluent supported the spread of antimicrobial resistance.

It seems further research is necessary to determine exactly how the secondary wastewater treatment process may affect the development of antimicrobial resistance and how facilities can mitigate its growth.

How does the threat of antibiotic-resistance affect your treatment facility? Is it a concern? If so, what preventative steps are you taking? WE_bug_web

  • Dr Edo McGowan.

    Laura, you touched on one of the most serious issues facing public health. Unfortunately, its politics not science. Many of those within the wastewater regulatory community, including California, seem not to appreciate the gravity of the issue or just hope it will go away. For example, the US-EPA has been downplaying this while the same time extolling the benefits of land applied sewage sludge spread across the nation’s farmland. There are numerous uncontested scientific studies discussing the large volumes of antibiotic resistant microbes found in sewage sludge, a byproduct of wastewater processing. There are also studies showing the failure of current standard lab tests to adequately protect the public health but the regulators fail to grasp this, or knowingly ignore it. Some pundits contend that the regulatory community is clientele captured by those it was set up to regulate. That issue ,”clientele capture” is a well documented pathology within governmental structures. Look at Congress and their purchase by the corporations. But, now we are discussing germs that can’t be stopped and with a rapidly dwindling array of antibiotics. Without antibiotics, there will be very few elective surgeries and a lot of poorly controlled battle-field wound-infections, Thinking about this and what’s likely to drop off the surgical menu, one will reflect on knee and hip replacements, dental implants, heart valve operations, or any number of invasive procedures that rely on antibiotics. Those wishing to grow old with an active life may find that unattainable absent antibiotics.

    Just to make the point, the State of California and the new recycled water program, its answer to drought, is encouraging the proliferation of toilet to tap. That program completely negates the need to recognize and track antibiotic resistant microbes or their genes in water. The training of sewer plant operators contains no studies covering this subject—-a topic too daunting and hence unnecessary to those in command. Nonetheless, in a Water Environment Research Foundation study, WERF 00-PUM-2T, where WERF is the research arm of the water industry, looked at recycled water, including that produced by our own Santa Barbara, the following was noted about current standard lab tests—— “The failure of measurements of single indicator organism to correlate with pathogens suggests that public health is not adequately protected by simple monitoring schemes based on detection of a single indicator, particularly at the detection limits routinely employed. Monitoring a suite of indicator organisms in reclaimed effluent is more likely to be predictive of the presence of certain pathogens, and a need for additional pathogen monitoring in reclaimed water in order to protect public health is suggested by this study.” ——–Santa Barbara had that information and did little to nothing with it. Another example of where decision-makers in charge of water failed to protect public health.

    My colleagues and I have tested this water and the results can be found here: http://www.ncbi.nlm.nih.gov/pubmed/?term=farhenfels+recycled+args

    “Not knowing” in this area is a highly practiced art within the regulatory community, especially those controlling the water we drink. But those who play the game of “non-action” are playing with the public’s health. Sure they may be on to and through the next revolving door or next political campaign or retired, but the pathogens really could care less and it is the people who elected them or whose tax dollars paid their salaries and their retirement benefits that will pay the ultimate price.

    Dr Edo McGowan

    • Laura S.

      Dr. McGowan, thank you so much for your insightful comments and for underscoring the gravity of this issue.

  • Marian Edson.

    Way back in the early 1960’s, Biologists were warning us that we needed to be very cautious in our use of antibiotics. Unfortunately, we didn’t heed it. I am confident that your research will find solutions.

  • Allen White.

    This is barely the tip of the proverbial “iceberg”.
    I have been following this for several years. Look up “CRE” (colosisten resistant e.coli) on the WEB. The major causes are two fold: 1- rampant, uncontrolled use of antibiotics in commercial “farm Factory” animals for ever increasing profits (ad infinitum); The ever increasing usages of flush toilets/ septic systems/ sewerage/ sewage treatment plants/ and land applications of human sewage sludges and farm animal wastes.
    “We have met the enemy and he is us” (pogo)
    Thanks and “good luck”

  • Hilary Noonan.

    A further concern for me is the effect on microorganisms on soil and nutrient cycling. Just as taking an antibiotic can wipe out the good microbial system in the human gut antibiotics in soil can wipe out the nutrient cycling system in soil. Our food crops have been losing nutrient quality and density for years. The two main culprits are a lack of proper mineralization and the use of products that destroy necessary beneficial microbes. Microbes serve nutrient cycling in soil. Plant availability of nutrients is controlled those microorganisms and often embodied in them. While some fertilizers are water soluble (and therefore susceptible to leaching) more sustainable fertilizers are not and it is microbial action in soil that makes those nutrients available to plants when they are needed. Crop production is affected by the quantity, quality and diversity of soil microorganisms. When that soil biome is damaged nutrient availability is damaged. If the plants don’t get it, we don’t get it.
    In addition, soil erosion increases dramatically when the biome is damaged. Using water for irrigation that has antibiotics, endocrine disrupters and other antimicrobials increases the problems of erosion, nutrient leaching and eutrophication.
    Until we pay attention to whole dynamic systems we will keep missing the boat on these issues.
    Thank you for the article. Pathogens are just one part of the story. The full story is even scarier!

    • Laura S.

      I couldn’t agree more, Hilary. Do you have any article links that you might be willing to suggest? I’d love to read more about these topics in an effort to deepen my understanding.

      • Hilary Noonan.

        Laura, I will get back to you. Right offhand, USDA has a lot of information on the loss of nutrient density in crops and on nutrient cycling through microbial communities. I will get more for you. It’s something I’ve been studying for the last 7 years. I’ve pulled information from a lot of different sources and figured out the links. I’ve had great people teaching me different aspects so it’s hard sometimes to trace it back, but I’m sure I can.

        • Laura S.

          I’m very grateful, Hillary. It’s such an important topic.


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