Atypical lethal systemic granulomatous inflammation caused by Pseudomonas aeruginosa in a green iguana (Iguana iguana): A postmortem case report

Abstract

A 5-year-old male green iguana (Iguana iguana) from a privately maintained outdoor enclosure was submitted for necropsy following a brief period of lethargy and anorexia, which rapidly progressed to death. A gross examination revealed coelomic and pericardial effusions, pulmonary consolidation, multifocal nodular lesions in multiple organs, most prominent and numerous in the lungs, accompanied by verrucous endocarditis. The histopathology report indicated widespread heterophilic and histiocytic granulomas with central necrosis and basophilic bacterial remnants in the lungs, heart, liver, and spleen. Microbiological cultures yielded Pseudomonas aeruginosa from coelomic and pericardial effusions, while special stains (acid-fast, PAS) and PCR for Mycobacterium spp. were negative, thereby ruling out mycobacterial and fungal infections. This is the first report of systemic granulomatous inflammation caused by Pseudomonas aeruginosa in a green iguana, underscoring its pathogenic potential in reptiles housed under suboptimal husbandry conditions and highlighting the importance of comprehensive diagnostics in exotic species.