A computational biologist, Arnau Vich Vila, presented his PhD research at the United European Gastroenterology conference in Barcelona (October 2019).  His paper, coauthored with his PhD advisor, Rinse K Weersma at the University Medical Center at Groningen, along with co-authors from Groningen (Netherlands), as well as from the Maastricht University Medical Center (also from the Netherlands)  , discussed the effects of various drug categories on the patency of our gut microbiome.

The study involved the identification of the populations within 1883 fecal samples.  (These involved three independent cohorts- one population based, the other IBD [inflammatory bowel disease] and IBS [irritable bowel syndrome] patients, with the third a mixture of IBD and health controls.)  Given that thousands of different species populate our gut, with populations on the order of more than ten trillion microbes in each of our guts, this was a vast undertaking.  The key parameters of the study were bacterial taxonomy, metabolic functions, antibiotic resistance, virulence factors, and bacterial growth rates.

The study identified certain drug categories (18 out of 41) that affected our stable population the most- intestinal infections, obesity, and other conditions linked to microbiome homeostasis.  Not surprisingly, proton pump inhibitors (PPI) [used to treat dyspepsia, peptic ulcers, gastric reflux, and infestations of H pylori] were prime effectors.  In addition, metformin (type 2 diabetes), antibiotics (for bacterial infections), and laxatives (for constipation) were also found to radically affect the microbiome ecology. To a lesser effect, SSRI’s (antidepressants) and oral steroids  were issues in the gut microbiome ecology.

Of the 18 categories of interest, 8 led to antimicrobial drug resistance and four dramatically affected the bacterial balance in the gut.  The researchers made sure that they corrected for polypharmacy (the effects when more than one drug category was involved) to ensure their results would be useful.

Antimicrobial resistance was afforded the gut microbiome when the drugs were oral contraceptives (anti-androgens), β-sympathomimetic inhalers, laxatives, as well as metformin and other oral  diabetes drugs.

Ingesting PPI increased the fatty acid production in our gut (as well as ‘leaking’ upper GI tract bacteria into the gut),while metformin augmented the ability of Escherichia coli (E coli) to thrive in the gut.  It was not surprising that antibiotics had dramatic effects on the gut microbiome; after all, their function is to kill microbes.  Nor was the ‘flushing effect’ of laxatives a surprise.

But, the antipressants ability to promote the population of Eubacterium ramulus, a harmful microbe [this was found in the IBD patients] was alarming.  As was the oral steroids promotion of methanogenic bacteria; these microbes promote increased BMI [body mass index] and obesity in the subjects.

There’s the major issue when we need to prescribe drugs for specific conditions; they often create new specific conditions that leave us in compromised health.

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