Fatal Bronchopneumonia and Tracheitis in a Green Turtle (Chelonia mydas) Caused by Serratia proteamaculans

Simple Summary Chelonian respiratory disease is often challenging to diagnose and treat due to unique species characteristics, environmental factors, co-morbidities, and limitations in diagnostic capabilities. Infections caused by previously unreported or poorly understood infectious agents may further complicate treatment efforts. Here, we describe an unusual case of fatal respiratory disease in a green turtle associated with Serratia proteamaculans infection. S. proteamaculans is a plant pathogen and possible cross-kingdom infectious agent, not previously reported to cause disease in reptiles. This case emphasizes the importance of microbial culture in managing chelonian respiratory disease and considers the potential for disease arising from the industrial or agricultural application of phytopathogens. In this report, we review the importance of understanding those bacteria that are often dismissed as opportunistic, explore treatment options for those times when opportunity leads to infection, and discuss the importance of bacterial culture and sensitivity in the respiratory disease of marine turtles. We also discuss the bacterium Serratia proteamaculans, a possible cross-kingdom pathogen, and invite the reader to think about the impact of biological alternatives to anthropogenic chemical use and the effects these solutions may have when environmental loads are artificially increased. A free-ranging subadult, male green turtle (Chelonia mydas) presented with radiographic evidence of pneumonia and died acutely. On necropsy, the trachea and bronchi were plugged by diphtheritic membranes, comprised of fibrin, necrotic debris, and colonies of bacilli, identified as Serratia proteamaculans. S. proteamaculans, typically considered an opportunistic plant pathogen, has rarely been described as causing disease in animals. This is the first report of S. proteamaculans causing severe necrotizing tracheitis and bronchopneumonia in a reptile.