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Antibiotics have revolutionized modern medicine by saving countless lives from bacterial infections. However, their widespread use has inadvertently harmed the delicate balance of the human gut microbiota. The gut microbiota, a complex community of bacteria, archaea, viruses, and fungi, plays a vital role in regulating metabolism, immune responses, and maintaining intestinal health. Antibiotics, especially broad-spectrum types, disrupt this ecosystem by eradicating both harmful and beneficial microbes, leading to a state known as gut dysbiosis.
Disruption of the gut microbiota can begin as early as during pregnancy. Antibiotic use during pregnancy and lactation alters the maternal microbiota and affects the infant’s initial microbial colonization. Studies in animals and humans have shown that infants exposed to antibiotics either prenatally or postnatally experience reduced microbial diversity, increased susceptibility to infections, and may have a higher risk of developing asthma, allergies, obesity, and metabolic disorders later in life. Preterm infants, often treated prophylactically with antibiotics, are particularly vulnerable to these effects, including necrotizing enterocolitis and sepsis.
In adults, antibiotic treatment also causes long-lasting shifts in gut microbial composition. Even short courses can lead to reduced levels of beneficial species such as Bifidobacterium and Lactobacillus, with changes persisting for weeks to years. Additionally, antibiotic exposure promotes the selection of antibiotic-resistant strains. The gut microbiota becomes a reservoir of antibiotic resistance genes (ARGs), facilitating their spread to pathogens through horizontal gene transfer.
The metabolic consequences of dysbiosis are far-reaching. Antibiotics alter the production of key metabolites like short-chain fatty acids and bile acids, disrupting energy homeostasis and glucose metabolism. This microbial imbalance has been linked to insulin resistance, inflammatory bowel diseases, and even mood disorders through the gut-brain axis.
To counteract these effects, therapeutic strategies such as probiotics, prebiotics, fecal microbiota transplantation (FMT), and bacteriophage therapy are being explored. These approaches aim to restore microbial balance, enhance immune function, and prevent the spread of antibiotic resistance.
Ultimately, careful stewardship of antibiotic use and a deeper understanding of host-microbe interactions are essential. Protecting the diversity and resilience of the gut microbiota is critical not only for individual health but also for combating the global threat of antibiotic resistance.
