Unusual microbes in asthma exacerbation: Alcaligenes xylosoxidans and Leishmania

Asthma is a chronic inflammatory condition characterised by a variable degree of airflow limitation. Exacerbations during the course of asthma often occur due to environmental factors or infectious, mostly viral, aetiology. The present study reports the case of a 61-yr-old male with severe asthma hospitalised due to increasing respiratory distress. Since recovery was delayed despite anti-obstructive/anti-inflammatory and antibiotic therapy, further diagnostic procedures, including bronchoscopy, were performed in order to attempt to identify the cause of the worsening respiratory condition. The surprising finding consisted of a rare coincidence of concomitant infection with the bacterial pathogen Alcaligenes xylosoxidans, grown from bronchoalveolar lavage fluid, and the protozoan parasite Leishmania spp., revealed by histopathological examination of bronchial mucosal biopsy specimens. This is the first report of an isolated bronchial mucosal involvement of Leishmania in an HIV-negative asthma patient following brief exposure in Leishmania-endemic regions. Further, to the best of the present authors' knowledge, this represents the first description of A. xylosoxidans in asthma, although it is questionable whether it was an infection or colonisation. The present observation identifies previously unreported microbial pathogens associated with asthma exacerbation. Further, the report highlights the importance of obtaining a thorough travel history and applying invasive diagnostic procedures in circumstances of treatment failure, even under unfavourable conditions.