Respiratory Fungal Infections

Endobronchial fungal infection caused by Candida albicans with main bronchus obstruction: a case report

Endobronchial fungal infection (EBFI) is a rare form of pulmonary fungal infection that especially affects immunocompromised patients. Furthermore, EBFI resulting in obstruction of the main bronchus is extremely rare. With the development of bronchoscopic techniques, rare cases of EBFI have been reported. A 68-year-old female was referred to the Department of Pulmonology for confusion and obtundation. The patient was diagnosed with septic shock due to acute pyelonephritis followed by obstructive EBFI. We performed bronchoscopic biopsy and endobronchial aspiration for culture. Biopsy showed yeast-like fungus and Candida albicans grew in the culture. EBFI has been under-recognized because of difficulties in confirming the diagnosis. Endobronchial ultrasound-guided transbronchial needle aspiration and bronchoscopy are used to improve the diagnosis of thoracic infection, such as tuberculosis. The role of bronchoscopy in the diagnosis of infectious diseases of the trachea or main bronchi is expected to widen in the future.

The lung microbiome

Historically, our understanding of lung microbiology has relied on insight gained through culture-based diagnostic approaches that employ selective culture conditions to isolate specific pathogens. The relatively recent development of culture-independent microbiota-profiling techniques, particularly 16S rRNA (ribosomal ribonucleic acid) gene amplicon sequencing, has enabled more comprehensive characterisation of the microbial content of respiratory samples. The widespread application of such techniques has led to a fundamental shift in our view of respiratory microbiology. Rather than a sterile lung environment that can become colonised by microbes during infection, it appears that a more nuanced balance exists between what we consider respiratory health and disease, mediated by mechanisms that influence the clearance of microbes from the lungs. Where airway defences are compromised, the ongoing transient exposure of the lower airways to microbes can lead to the establishment of complex microbial communities within the lung. Importantly, the characteristics of these communities, and the manner in which they influence lung pathogenesis, can be very different from those of their constituent members when viewed in isolation. The lung microbiome, a construct that incorporates microbes, their genetic material, and the products of microbial genes, is increasingly central to our understanding of the regulation of respiratory physiology and the processes that underlie lung pathogenesis.