Fungal Isolates of the Respiratory Tract in Symptomatic Patients Hospitalized in Pulmonary Units: A Mycological and Molecular Epidemiologic Study

INTRODUCTION: Fungal respiratory infections are being recognized with increasing frequency in parallel with an expanding population of immunocompromised patients. In most cases, colonization is the first step in the progression to pulmonary fungal infection. This study was designed to evaluate the distribution of fungal elements in the respiratory tract of symptomatic patients hospitalized in pulmonary units. METHODS: This descriptive cross-sectional study was carried out over a period of two years, from October 2017 to October 2019 in Guilan province, located in Iran’s northern region. In the current study, bronchoalveolar lavage or sputum specimens were collected. All samples were analyzed by direct microscopy using KOH 10% and culture. Fungal identification was accomplished by internal transcribed spacer (ITS) and beta-tubulin sequencing. Also, in patients suspected of invasive pulmonary aspergillosis, BAL specimens were tested for galactomannan (GM) antigen. RESULTS: A total of 384 lung specimens (192 bronchoalveolar lavage (BAL) and 192 sputum samples) were obtained from symptomatic patients hospitalized in pulmonary units. Of these, 137 (35.67%) were positive in direct examination and culture. Among the 137 positive cases, most isolates were from male patients 86 (62.77%) and most of them were between 46 and 72 years. Candida albicans (37.22%) and Candida tropicalis (21.89%) represent the two most commonly isolated species in the current study. Cough (94.16%), dyspnea (81.02%), purulent sputum (62.04%) and weight loss (56.2%) were the predominant symptoms and tuberculosis (24.81%), chemotherapy (21.89%) and diabetes mellitus (19.70%) were the predominant underlying conditions. Also, 5 cases of invasive pulmonary aspergillosis and 1 case of mucormycosis were diagnosed. CONCLUSION: Candida albicans was the most common fungal species isolated from symptomatic patients hospitalized in pulmonary units. Tuberculosis, chemotherapy and diabetes mellitus were important underlying conditions for pulmonary fungal colonization and/or infection.