Impact of antibiotics on the gut microbiota
A major medical discovery of the 20th century, antibiotics have saved millions of lives, but their excessive and often inappropriate use has led to the emergence of multiple forms of antibiotic resistance. This past November, the WHO publicly highlighted the importance of using antibiotics prudently*.
The use of antibiotics increased by 65% between 2000 and 2015. This new study reminds us that when eradicating pathogenic germs responsible for infections, antibiotics can also destroy beneficial bacteria in the gut microbiota, thereby causing an imbalance (dysbiosis) within this ecosystem, with potential short and long-term consequences.
Adverse effects on microbiota in the short and medium term...
The first thing to note is that antibiotics disrupt the balance existing in the gut microbiota. By eliminating certain bacteria, they allow other pathogens to occupy the free space and multiply. One consequence is antibiotic-associated diarrhea, which affects between 5% and 35% of patients but usually resolves spontaneously within a few days. However, some forms of diarrhea can be more severe and when caused by Clostridioides difficile they may even be fatal. The second observation is that antibiotics are linked to a reduction in microbiota diversity. A return to equilibrium may take some time, with certain bacteria still absent after several months. Lastly, the repeated or inappropriate use of antibiotics leads bacteria to develop strategies to circumvent their effects. Bacteria can become antibiotic-resistant, thereby rendering treatments ineffective. The experts’ predictions are unsettling: unless drastic measures are taken to address the issue, the misuse of antibiotics could cause ten million deaths worldwide by 2050.
...with serious long-term consequences
Systemic use of antibiotics is still far too widespread among infants and children and is thought to be associated with the development of diseases later in life (obesity, asthma, allergies, inflammatory bowel disease). This battle is far from won and the scientific community is actively seeking new strategies to restore the gut microbiota, based on multiple modulation pathways (diet, probiotics, prebiotics).
Ramirez J, Guarner F, Bustos Fernandez L, et al. Antibiotics as Major Disruptors of Gut Microbiota. Front Cell Infect Microbiol. 2020 Nov 24