Haemophilus influenzae: mere passenger or true driver of bronchiectasis?

By Ana Espino | Published on August 19, 2025 | 2 min read

#Influenza #Bronchiectasis  


Bronchiectasis is a chronic lung disease characterized by irreversible dilation of the bronchi, leading to mucus accumulation, persistent inflammation, and increased susceptibility to respiratory infections. Despite therapeutic advances, management remains limited by the challenge of controlling chronic inflammation and preventing frequent exacerbations. Recent evidence suggests an infectious etiology in the development and progression of the disease, underscoring the importance of microbial agents in its evolution.

A major challenge therefore lies in identifying infectious agents that fuel the vicious cycle of inflammation–infection–tissue damage, in order to better target clinical management. Haemophilus influenzae (H. influenzae), a bacterium frequently isolated in these patients, raises questions about its exact pathogenic role—whether it acts as a mere colonizer or as a central driver of disease progression. This study was initiated to analyze the impact of H. influenzae on pathophysiology, exacerbations, immune response, and prognosis in patients with bronchiectasis.  

H. influenzae, the prime suspect?

This review is based on clinical and microbiological studies of patient cohorts with bronchiectasis. The studies assessed the frequency of H. influenzae isolation in sputum and bronchial samples. Host response—particularly neutrophilic inflammation and the production of pro-inflammatory cytokines—was observed. Several longitudinal studies were included to establish a link between chronic colonization by H. influenzae, exacerbation frequency, and decline in lung function.  

Findings show that H. influenzae is one of the most frequently isolated pathogens, often detected chronically. Its presence is associated with persistent neutrophilic inflammation, increased production of pro-inflammatory cytokines, and worsening bronchial remodeling. Several studies demonstrate that colonized patients face a higher risk of exacerbations, reduced lung function, and poorer quality of life. Immunologically, chronic infection with H. influenzae is accompanied by an insufficient antibody response, suggesting the host’s inability to eradicate the bacterium effectively. Culture and molecular biology studies also confirm substantial genetic variability among strains, complicating treatment and promoting persistence.  

Toward targeted management?

Bronchiectasis remains a burdensome chronic condition, sustained by a vicious cycle of infection and inflammation. Available data show that H. influenzae plays a central role in symptom worsening and increased exacerbation risk, making it a potential therapeutic and diagnostic target. The aim of this review was to clarify its involvement in the disease and guide research toward more targeted strategies. While evidence supports its active role, limitations include the difficulty of distinguishing colonization from infection, heterogeneity among studies, and a lack of longitudinal data.  

Future research should identify specific biomarkers, improve antibiotic strategies, explore new vaccine approaches, and develop personalized protocols to better control the impact of H. influenzae on the progression of bronchiectasis.

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