Antibiotic resistance

Allison Cartwright is our ECS Events Officer. Ahead of our 3rd Antimicrobial Resistance Conference in collaboration with the Academy of Pharmaceutical Sciences and the Royal Society of Chemistry, she looks at one of the biggest threats facing our healthcare system today. 

Antibiotic resistance in microbes is one of the many topics that grips my attention. This phenomenon has massive impacts on human and animal health by increasing fatalities, needless suffering and a strain on our economy.

The concern that we are entering a ‘post-antibiotic’ era can cause insomnia and concern, as nobody wants to see their loved ones, fellow humans and animals endure an incurable infection.  Despite this, it’s hard not to feel fascination and respect for the many microbes that have developed resistance.


Gene genies

The process of acquiring resistance isn’t easy and although it can occur naturally and has occurred prior to human evolution, undoubtedly, we have helped to accelerate the development of antibiotic resistance. So how do microbes do it?

Generally, it is thought to occur through two mechanisms: mutation or gene transfer. A mutation occurs when a bacterium develops resistance through a change in its own DNA, often because of selection pressure from antibiotics being applied at a concentration that does not kill the bacteria.

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Mutation to facilitate antibiotic resistance is rare. Instead most resistance is acquired from other bacteria who already have resistance genes. Bacteria have an amazing ability to swap and share genetic material with other bacteria.

The most common method for gene sharing is conjugation. When bacteria come into contact, they can form a link and transfer antibiotic resistance from one bacterium to another.

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Stream of concern

I am looking forward to attending SfAM’s Antimicrobial Resistance Conference in November as this two-day event will cover aspects of drug discovery and antibiotic resistance in waste water. From my PhD study, I have had the opportunity to sample stream water for antibiotic resistant microbes, and I have also tested effluent from a municipal wastewater treatment plant.

I selectively grew enterococci from the water samples and tested them for the resistance to six antibiotics: ampicillin, erythromycin, rifampicin, tetracycline, trimethoprim, and vancomycin. I was shocked by the results as I found enterococci resistant to all these antibiotics except erythromycin, and most of the samples were from small rural streams.

Enterococcus faecalis

Enterococcus faecalis

What lies beneath

All four streams were in the northern part of Ireland and contained enterococci resistant to ampicillin, one of the most common antibiotics used to treat Enterococcus faecalis infections. Three of the streams had enterococci with resistance to rifampicin.

One stream was sampled where waste water effluent entered the channel, and the sampling site at another stream was downstream of a large cattle farm. The enterococci from the site below the wastewater outlet had enterococci with resistance to ampicillin and rifampicin, while the enterococci downstream of the cattle farm were resistant to ampicillin, rifampicin, trimethoprim and vancomycin.


Getting wasted

A friend often reminds me that waste water combines unmetabolized antibiotics at low concentrations, with the bacteria from sick people and so the results from the waste water were not too surprising to me, but the results from the stream by the cattle farm came as a shock.

It was only a small stream, not even two meters wide! So how could the enterococci have such resistance? I have heard that cattle feed used to contain antibiotics as a prevention for disease, but this has been regulated in Europe since 2004 and so could explain the resistance.

Could the resistant microbes be a response to veterinary medicine or the leakage of sewage from the septic tanks in farms and rural house? I would need to do further investigation to answer this. I hope that some of the research being showcased at the conference by my fellow scientists will help to give me the answer to a question that has eluded me.

stream Wisconsin

Working for the future

I am also fascinated to learn about novel therapeutics and drug discovery which will be discussed at the conference. Currently, my experience with antibiotic resistant microbes has been environmentally based, but considering my river water study, I truly believe that antibiotic resistance is a key problem that will be faced by my generation.

If we are to solve this problem we need to work together to address the problem through all channels for spread while identifying new methods to treat microbes. Only by understanding and reducing the creation of resistance, along with the release and spread of antibiotic resistant microbes between the clinic and environment will we be able to create a healthier world where the spread of resistance can be better controlled.

At the moment, bacteria are a step ahead of our brilliant scientists, so we all need to work together and take responsibility for how and when we use antibiotics for ourselves and our animals.  We also need to pay attention to how the drugs we use are released or discarded.  If we don’t, the post antibiotic era could come sooner than we think.

On the 23 and 24 November 2017, the Society for Applied Microbiology will hold its 3rd Antimicrobial Resistance Conference in collaboration with the Academy of Pharmaceutical Sciences and the Royal Society of Chemistry.

Categories: Feature Articles

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