Acute Appendicitis and the Microbiome: A Review of Microbial Signatures

<b><i>Introduction:</i></b> Acute appendicitis remains one of the most common surgical emergencies, yet its pathogenesis is incompletely understood. Although mechanical luminal obstruction has traditionally been considered the initiating factor, emerging evidence suggests that the appendix hosts a unique microbial community that may influence disease onset and severity. <b><i>Methods:</i></b> We conducted a narrative review that summarizes current data on the role of microbiota in appendicitis, while focusing on differences between complicated and uncomplicated presentations. <b><i>Results:</i></b> High-throughput sequencing studies have identified key taxa associated with inflamed appendices, including <i>Fusobacterium</i>, <i>Prevotella</i>, and oral cavity genera such as <i>Gemella</i> and <i>Parvimonas</i>. On the contrary, protective commensals such as <i>Faecalibacterium prausnitzii</i> and <i>Akkermansia muciniphila</i> appear depleted. Studies suggest that there is significant variation regarding the microbial composition of complicated and uncomplicated cases. We also examine the role of the appendix as a microbial reservoir and the potential health consequences of its removal. Finally, we discuss how microbiome-based approaches may improve treatment, particularly antibiotic agent selection both in operative and non-operative management. <b><i>Conclusion:</i></b> Current evidence supports that appendicitis may represent a disease spectrum carrying multiple rather than a single microbial signature that dictates different pathophysiologic processes.