Study finds correlation between antibiotic use and inflammatory bowel disease

Modern antibiotics have been around for nearly a century, since Alexander Fleming accidentally grew a fungus that could produce penicillin in his lab in the 1920s. Since then, antibiotics have been used to treat everything from childhood ear infections to tuberculosis and sexually transmitted diseases like chlamydia and gonorrhoea.

(Indeed, we might indeed be hard-pressed to find someone who has never taken an antibiotic in their life.)

That said, the use of antibiotics comes with a set of trade-offs. For one, antibiotics, especially broad-spectrum ones like Rifampin and Amoxicillin, don’t just kill or stop the bacteria that’s causing infection, but also a range of other bacteria that live harmoniously in our bodies, including in our intestines.

Speaking of problems associated with antibiotic use, it is worth noting that antibiotic misuse and overuse are also linked with antibiotic resistance. In fact, Fleming himself pointed to the dangers of overuse or improper use of antibiotics leading to antibiotic resistance in Nobel Prize lecture in the 1940s!

Inflammatory bowel disease (IBD) is a chronic illness with no definitive cure, though there are treatment protocols and lifestyle changes to manage it. Surgery (proctocolectomy) can reverse ulcerative colitis in some cases, but most patients are prescribed a special diet for IBS and exercises for IBS to manage symptoms like diarrhoea, abdominal pain, fatigue, fever, blood in the stool, loss of appetite and unwanted weight loss.

The exact cause of IBD is unknown, though researchers suspect that an immune system dysfunction may be at the root of it. Inflammation is a natural response of the body whenever there is an injury or attack by a pathogen. Sometimes, though, the immune response goes haywire and starts to attack healthy cells of the body.

In 2019, an article published in Translational Pediatrics, a peer-reviewed journal, summarised what we know about IBD, antibiotics and the gut microbiome. The paper listed at least three things of note:

• First, people with IBD have fewer gut microbes like bacteroides and firmicutes that have an anti-inflammatory effect.
• Second, IBD may be triggered in genetically predisposed people by a change in gut microbiome.
• And third, “antibiotics are associated with increased dysbiosis…. Long-term changes to microbiome continue well beyond cessation of therapy”. Dysbiosis is an imbalance in the natural microbes that live on and inside our bodies.

The article went on to suggest it might be possible to manage or treat IBD by manipulating the gut microbiome using drugs and other therapies (including fecal transplant).

The study at the Karolinska Institutet and Harvard Medical School offers researchers one more line of query to focus on: a possible causation link between IBD and antibiotic use. Ironically, antibiotics like ciprofloxacin are sometimes used to control the symptoms and complications of IBD which may include anal fissures and secondary infections.

The Karolinska-Harvard study included 23,982 people diagnosed with new-onset IBD between 1 January 2007 and 31 December 2016. It also looked at people in two control groups who didn’t have IBD. The first group comprised 117,827 people of similar background, age and sex as the patients. The second control group comprised 28,732 siblings of patients. The study found a clear correlation between people who had taken antibiotics and those who developed IBD. It also found that the risk increased in people who took antibiotics more than once.

Dr Long Nguyen, the study’s lead author, said in a release: "I think this affirms what many of us have suspected - that antibiotics, which adversely affect gut microbial communities, are a risk factor for IBD… However, despite this compelling rationale and seemingly intuitive presumption, there have been no population-scale investigations to support this hypothesis until now."

The researchers urged that more probes be done on this subject, to truly understand the link between antibiotic use and IBD.