Design and application of a real time molecular polymerase chain reaction (PCR) for the detection of Erysipelothrix rhusiopathiae in cetaceans

EVA SIERRA; ANTONIO FERNÁNDEZ; IDAIRA FELIPE-JIMÉNEZ; SIMONE SEGURA GÖTHLIN; PABLO DÍAZ SANTANA; CRISTIAN M. SUÁREZ SANTANA; CARLA FIORITO; MANUEL ARBELO

Conferencia; 34th European Cetacean Society Conference; 2023

Erysipelothrix rhusiopathiae is a facultative, non-spore-forming, non-acid-fast, small, Gram-positive rod-shaped bacteria with zoonotic potential. It has been isolated from a wide variety of mammals, birds, reptiles, fish, and insects from which it could be a pathogenic or a commensal microorganism. E. rhusiopathiae is ubiquitous and can persist for a long period of time in the environment, including marine locations; although secretions of infected animals (feces, urine, and/or respiratory discharges) and the skin mucus of contaminated fish are thought to be the main sources of infection through dermal abrasions or ingestion. Since the first description in porpoise in 1956, E. rhusiopathiae infection is considered one of the most serious infectious diseases of cetaceans. Cutaneous and septicemic forms of E. rhusiopathiae have been described in several cetacean species worldwide, with a predominantly acute course of the disease and commonly fatal. Gross changes to affected organs are often subtle or non-specific and included pulmonary edema, hemorrhage, congestion and/or serosanguineous effusion of various organs. Bacterial emboli, typically associated with systemic congestion, edema, hemorrhages, and fibrinocellular thrombi, were commonly observed on histopathology. These bacteria are frequently intravascular, either extracellular or intramonocytic/macrophagic. Although blood culture is the gold standard of diagnosis, molecular polymerase chain reaction (PCR) significantly improves the accuracy and shortens the duration for speciation. A SYBR® Green real-time PCR for rapid and specific detection of E. rhusiopathiae was developed based on the DNA polymerase IV gene (GenBank Acc. No.: KX274429). The PCR was successfully applied to test several cases of E. rhusiopathiae infection in stranded cetaceans in the Canary Islands previously confirmed by histopathology, immunohistochemistry and culture and bacterial identification (API Coryne system).