The association of bacterial agents and flagellated protozoans in the etiopathogenesis of subspectacular abscesses in snakes

Objectives: To describe the etiology, clinical pathology, and treatment of subspectacular abscesses (SAs) in 16 snakes. Animals Studied: Sixteen snakes from private captive collections that were presented at a veterinary teaching hospital and diagnosed with SAs. Procedures: Exudate was collected from SAs via percutaneous aspiration or by performing a partial spectaculectomy and submitted to direct light microscopic examination and/or microbiological examination. Results: Bacterial isolates were cultured from exudate samples in 12 out of 16 snakes and comprised Pseudomonas aeruginosa isolates that showed identical antimicrobial susceptibility patterns in seven cases. Direct light microscopic examination demonstrated the presence of flagellated protozoa in the exudate in 10 out of 16 snakes and in all of these snakes, concurrent oropharyngeal flagellated protozoan infection could be demonstrated. Combined flagellated protozoan and bacterial SA infection was demonstrated in six snakes. Comparison of small subunit ribosomal RNA gene sequences of flagellated protozoans that were detected in the exudate of SAs from four snakes revealed they represented the parabasalians Monocercomonas colubrorum and Hypotrichomonas acosta in one and three cases, respectively. In all snakes, successful treatment of the SAs was achieved following surgical debridement of the subspectacular space combined with antimicrobial treatment. Conclusion: Bacteria as well as flagellates are considered to reach the subspectacular space through ascending infection from the oral cavity via the lacrimal duct. Although opportunistic bacterial infection presumably constitutes the predominant cause of SAs in snakes, the role of flagellate infection in the pathogenesis of this disorder should be further elucidated.