Recurrent pulmonary infection, a vicious cycle of multifactorial interactions, and prevention/treatment strategies

Recurrent pulmonary infection (RPI) refers to the frequent and repeated episodes of lower respiratory tract infections. At its core, it represents a vicious cycle arising from the disruption of the homeostatic balance among pathogens, host immunity, and pulmonary architecture. RPI accounts for a considerable proportion of pediatric pneumonia cases, and the cumulative incidence among elderly patients hospitalized for pneumonia is also markedly elevated, imposing a substantial disease burden. The etiologies are notably diverse, beyond common pathogens such as bacteria and viruses, the ubiquity of asymptomatic colonization, underlying comorbidities, immune deficiencies, medication-related factors, and aspiration all constitute critical predisposing factors. This review summarizes the pathogenic characteristics of RPI, host-related factors, and the mechanistic roles of structural lung damage in infection recurrence. It further focuses on the current advances and limitations of precision diagnostic approaches (metagenomic sequencing), immunomodulatory and microbiome-targeted interventions, and vaccination strategies. Existing evidence suggests that the clinical benefits of these interventions in RPI remain to be validated by more high-quality studies. The aim of this article is to provide a reference for the clinical management of RPI and to inform future research directions.