The Impact of Antimicrobial Therapy on the Development of Microbiota in Infants

<b><i>Background.</i></b> The establishment and diversity of the gut microbiota during early childhood are fundamental for immune regulation and metabolic processes, with factors such as prematurity, delivery method, antibiotic treatment, and breastfeeding significantly impacting microbiome development and potential health outcomes. <b><i>Objectives/Methods.</i></b> This comparative study examined the gut microbiota composition in children aged 6–8 and 9–12 months, born via spontaneous labor at ≥38 weeks’ gestation, who either did not receive antibacterial therapy or required beta-lactam antibiotics. The composition of the colonic microbiota was analyzed in these fecal samples using a quantitative real-time PCR (qRT-PCR). <b><i>Results.</i></b> Significant differences in microbiota composition were observed between groups. Children treated with antibiotics exhibited a statistically significant reduction in alpha diversity indices (Shannon and Simpson), along with decreased colonization of key functionally important microorganisms, including obligate anaerobic bacteria such as <i>Faecalibacterium prausnitzii</i>, <i>Clostridium leptum</i>, <i>Bacteroides</i> spp., and metabolically active <i>Bifidobacteria</i> (<i>B. bifidum</i>, <i>B. breve</i>, <i>B. longum</i>). <b><i>Conclusions.</i></b> These microbiota alterations may adversely affect child health by diminishing microbial balance and functional potential, especially during this critical period of immune and metabolic development. The decline in anti-inflammatory, short-chain fatty acid-producing bacteria elevates the risk for allergic, atopic, dysbiotic, and metabolic conditions. Recognizing these impacts underscores the importance of strategies to supports microbiota restoration after antibiotic use, such as probiotics, prebiotics, and dietary interventions. Further research should focus on microbiota recovery dynamics to facilitate early intervention and optimize pediatric health outcomes. Overall, understanding antibiotic effects on gut microbiota can guide more judicious treatment approaches, reducing long-term health risks.