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Friends, Foes, and Everything In Between - Why Bacteria Get a Bad Rap

March 31, 2017


By Meghan Krizus

  A petri dish containing E. coli strain HT115(DE3), an example of how bacteria provide essential tools to scientists

A petri dish containing E. coli strain HT115(DE3), an example of how bacteria provide essential tools to scientists

Humans have a fraught relationship with bacteria. Advertising for antibacterial soaps, disinfectants, and air purifiers would have us believe that all bacteria are enemies to be eliminated. But contradictions to this message pour in from the flourishing market of probiotics, insisting that our health depends on consuming as many bacteria as we can.

Such a contradiction seemingly exists in science, too; much research has shown us the importance of nurturing our internal microbiomes, of which bacteria are the integral part. Here at the LTRI, for instance, Dr. Mark Silverberg and Dr. Kenneth Croitoru have demonstrated that a healthy relationship between host and microbiome is key for the health of both. At the same time, however, researchers such as Dr. Frank Sicheri investigate the virulence factors of pathogenic bacteria like Shigella.

So are bacteria friends or foes? The answer is more complicated and nuanced. Some bacteria are friendly and perform essential processes that are bodies are incapable of doing effectively alone. Most are indifferent to us. A few are dangerous.

So why can some bacteria be so good for us, while others are associated with disease? Here, at least, there is a simple answer: diversity. Bacteria are incredibly diverse, as the name “bacteria” refers to the broadest of taxonomic ranks: the domain. As a result of this enormous definition, individual types of bacteria are only very distantly related. For instance, many bacteria are only as similar to one another as you or I are to the remnant of sea sponge used to exfoliate skin. Because of this diversity, bacteria occupy very different ecological niches and roles. This allows some to be very beneficial to us, while others are decidedly dangerous.

What are some helpful things bacteria do for us? They are essential, for instance, to the basic process of eating. Bacteria are present in yogurt, cheeses and other dairy products, responsible not only for preserving these foods from decay, but also for giving them unique flavours. And even if you’re not a fan of dairy, bacteria still do a lot for you when it comes to food. We all owe the bacteria living in our intestinal tract a huge debt for the role they play in our digestion, allowing us to harvest and absorb important nutrients from the food we consume.

The presence of beneficial bacteria in our intestinal tract is advantageous not only because of nutrient absorption, but also because they keep more harmful bacteria under control. The CBC documented one such case in the Nature of Things’ episode “The Antibiotic Hunters,” showing how restoring a healthy population of microbes to a patient’s colon was able to treat a drug-resistant infection of the bacterium Clostridium difficile, which can be a scourge in hospital environments.

Indeed, scientists and physicians owe much to bacteria. Since its discovery in 1885, Escherichia coli (more commonly known as E. coli) has been the cornerstone of molecular biology. The most important molecular tools use living bacteria like E. coli, or their products. This means that paradigm-altering research like The Human Genome Project, and its applications in genome sequencing and personalized medicine, would have been impossible without bacteria.

Of course, there are dangerous bacteria, too, since the kindly bacteria we rely on for the flavour of our favourite Stilton cheese have deadly cousins. Mycobacterium tuberculosis is responsible for tuberculosis, an infection that remains difficult to treat and throughout history has claimed the lives of millions. Also of critical concern is Clostridium difficile. While healthy individuals can harbour this bacterium without negative effect, some become extremely ill after infection. Especially dangerous because it is often resistant to antibiotics, prevalent in hospitals and other healthcare facilities, and causes debilitating (and often fatal) symptoms, C. difficile is just one of the many vicious relatives of helpful bacteria.

The confusing and mixed messaging around bacteria has led to over-compensation and concern, even phobia. While hygiene is important, and handwashing the most effective means of stopping the spread of infectious agents, do we really need anti-bacterial soaps outside of an operating room or clinical facility? The simple answer is no. Moreover, eradicating bacteria from our normal environment is futile, as they’ll quickly return and repopulate their natural ecological niches.

Bacteria are highly diverse individuals, and should be treated as such. We should neither underestimate the harmful potential of bacteria, nor hesitate in treating them. If prescribed antibiotics, the whole course should be taken as directed. Not to mention that new drugs and novel antibiotics are desperately needed to treat the increased prevalence of multiple antibiotic-resistant “superbugs.” But in our zeal to deal with the hazardous bacteria, we should not forget how beneficial others can be.

As researchers at LTRI, we get to see and harness this great bacterial diversity. We value the good that bacteria can do, understanding that without bacterial tools like restriction enzymes, much of our research wouldn’t be possible. We have also made discoveries key to understand how bacteria make up part of the microbiota of our gut, and are responsible for keeping us healthy. On the other hand, we also recognize their danger; hence, some of us study pathogenic bacteria, and how we can defend ourselves against them.

And, of course, the worm researchers among us merely use bacteria as food for their model organisms!


Find out more! We have lots of resources to help.

Learn more about our pioneering research, investigating both the good and the bad of bacteria:





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