Lacey, Melissa

Sheffield Hallam University Research Archive

Gut microbiome: meet E coli – the infamous bacteria with an unfair reputationLACEY, Melissa <http://orcid.org/0000-0003-0997-0217>Available from Sheffield Hallam University Research Archive (SHURA) at:http://shura.shu.ac.uk/33672/This document is the author deposited version.  You are advised to consult the publisher's version if you wish to cite from it.Published versionLACEY, Melissa (2024). Gut microbiome: meet E coli – the infamous bacteria with anunfair reputation. The Conversation. Copyright and re-use policySee http://shura.shu.ac.uk/information.htmlSheffield Hallam University Research Archivehttp://shura.shu.ac.ukAcademic rigour, journalistic flairGut microbiome: meet E coli – the infamous bacteria with anunfair reputationPublished: May 3, 2024 12.16pm BSTMel LaceyAssociate Professor of Molecular Microbiology, Sheffield Hallam UniversityEscherichia coli (which most of us know better as E coli) has a bit of a bad reputation. Many know itas the harmful bug that can cause a stomach illness, urinary tract infections, kidney failure and evendeath. But this reputation is slightly unfair. There are many types of E coli – and many play animportant role in a healthy gut microbiome.E coli was discovered nearly 140 years ago when it was isolated from the poop of a German baby.Since then, it’s become the most studied species of bacteria – and arguably the most studied species ofall life – on Earth.This bacteria has many different strains, most of which are friendly. So why does E coli have a badreputation?Most strains of E coli play an important role in the healthy human gut microbiome. They’re one of the first bacteria to live in the intestine of babies, paving the way for other good bacteria to join them.E coli are one of the first bacteria to live in a baby’s intestines. fusebulb/ ShutterstockIn a healthy adult gut, friendly E coli work tirelessly to produce vitamin K (which helps clot blood andsupports wound healing) and prevent disease-causing bacteria from taking hold. The strain E coliNissle is actually a probiotic – meaning its presence in the gut prevents infections. This strain wasfirst identified in 1917 after it was isolated from the poop of a German man who had not been affectedby a diarrhoea outbreak that had infected many of his fellow soldiers.But sometimes, these friendly strains find themselves in the wrong place at the wrong time. Forexample, even though between 80-95% of urinary tract infections are caused by E coli, this is oftenmerely because of the proximity of the anus and the entrance of the urinary tract, which allows thebacteria to physically move from one area to the other.This means strains that are well behaved in the gut cause an infection in the urethra.But other strains of E coli, which do not normally live in our gut and are unwelcome guests, areperhaps more deserving of the bacteria’s bad reputation. The strain E coli 0157 is one such strain, andcan be found in the gut of cows, sheep and goats.When it infects humans, it causes abdominal pain, bloody diarrhoea, kidney disease – and, in sometragic cases, death. It arrives in the human gut through contaminated foods, direct contact withanimals or their environments. This serves as a reminder for all of us to keep a clean kitchen, cookmeat well and wash our hands after touching or being around livestock.A healthy gutEach person’s microbiome is different, so the amount of E coli you have living there – and whatstrains – will vary. Sometimes, these differences are due to dysregulation – where the gut’s microbialcommunity becomes imbalanced. This can have a number of implications for health.In inflammatory bowel diseases – including irritable bowel syndrome, Crohn’s disease and ulcerativecolitis – the number of E coli is often higher than in a healthy gut. But we don’t currently know ifincreased numbers of E coli in the gut microbiome drive inflammatory bowel disease, or if the diseasemakes the gut less inhabitable for other species of bacteria – leading to an increase in the amount ofspecific strains of E coli.Colorectal cancer and gut microbiome dysregulation are also correlated – again with a higher amountof E coli in the diseased gut. This may be due to a group of nasty E coli strains that make moleculescalled cyclomodulins and then excrete them near human cells.Cyclomodulins are carcinogenic, altering how the human cells grow and develop, implying that someE coli strains may increase the likelihood of their human host developing cancer.A woman sitting on a couch holds her stomach in pain.The harmful strain E coli 0157 can cause stomach pain – among other symptoms. Prostock-studio/ ShutterstockBut while E coli may have a bad reputation, not all strains are actually bad for us – and remain animportant part of a health gut microbiome.This article is part of Meet Your Gut Microbes, a series about the rich constellation of bacteria,viruses, archaea and fungi that live in people’s digestive tracts. Scientists are increasingly realisingtheir importance in shaping our health – both physical and mental. Each week we will look at adifferent microbe and bring you the most up-to-date research on them.

Gut microbiome: meet E coli – the infamous bacteria with an unfair reputation

https://shura.shu.ac.uk/33672/1/Lacey-GutMicrobiomeMeet%28VoR%29.pdf

Gut microbiome: meet E coli – the infamous bacteria with an unfair reputation

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