German scientists have discovered protective drugs that may lessen the collateral damage caused by antibiotics.
The researchers found that the protective drugs didn’t compromise the effectiveness of antibiotics against harmful bacteria.
The researchers, from the European Molecular Biology Laboratory (Heidelberg), also identified the classes of antibiotics that are most disruptive to healthy gut bacteria.
Among the drugs that might offset this disruption are an anticoagulant (dicumarol), a type of gout medication (benzbromarone), and two anti-inflammatory drugs (tolfenamic acid and diflunisal).
Common side effects from antibiotics include nausea and bloating, but they can also trigger more serious inflammatory and immunological conditions.
Antibiotics’ mixed blessing
We have a love-hate relationship with antibiotics. One the one hand, we’re grateful when they’ve killed off an infection that was making life awful.
And we’re not thrilled that bacteria has grown increasingly resistant to antibiotics and may essentially leave us stranded, as we were in the days of smallpox, cholera, diphtheria and so forth.
On the other hand, antibiotics can be hard on the gut, metabolism and immune system. This can leave us with an added layer of feeling unwell, or worse.
A delicate balance
As the researchers describe it, antibiotics are a disruptor of the trillions of microorganisms in the human gut that “profoundly impact health by aiding digestion, providing nutrients and metabolites, and working with the immune system to fend off harmful bacteria and viruses”.
The problem is that antibiotics tend to work more like a scatter-shot machine-gun than a sharp shooter. While dispatched to eliminate “bad” bacteria, they can play hell with the “good”, which puts gut health out of whack.
A common problem caused by this imbalance are Clostridioides difficile infections that cause diarrhea and colitis. These infections can be life-threatening, along with long-term health problems such as obesity, allergies, asthma and other immunological or inflammatory diseases.
What to do?
According to a statement from the European Congress of Clinical Microbiology & Infectious Diseases (where the findings were presented last month):
The researchers systematically analysed the growth and survival of 27 different bacterial species commonly found in the gut following treatment with 144 different antibiotics.
They also assessed the minimal inhibitory concentration (MIC) – the minimal concentration of an antibiotic required to stop bacteria from growing – for over 800 of these antibiotic-bacteria combinations.
Good news and bad guys
There was some good news: most gut bacteria had slightly higher MICs than disease-causing bacteria. This suggests that “at commonly used antibiotic concentrations” most of the tested gut bacteria wouldn’t be affected.
However, two widely used antibiotic classes – tetracyclines and macrolides – hindered healthy bacteria from growing sufficient concentrations to stop the growth of disease-causing bacteria.
They also “killed more than half of the gut bacterial species they tested, potentially altering the gut microbiome composition for a long time”.
Quest for a solution
Because drugs interact differently across different bacterial species, the researchers investigated whether a second drug could be used to protect the gut microbes.
They combined the antibiotics erythromycin (a macrolide) and doxycycline (a tetracycline) with a set of 1197 pharmaceuticals.
The idea was to find drugs that would protect two abundant gut bacterial species (Bacteriodes vulgatus and Bacteriodes uniformis) from the antibiotics.
Among several promising candidates were an anticoagulant, a gout medication, and two anti-inflammatory drugs.
Importantly, these drugs did not compromise the effectiveness of the antibiotics against disease-causing bacteria.
