First Report of Candida Sake Isolated From Cultured Rainbow Trout (Oncorhynchus Mykiss, Walbaum) Juveniles in Turkey

Abstract

In this study, we have isolated Candida sake for the first time from rainbow trout juveniles in Turkey. The disease was observed in juvenile fish (0.5 g) at a water temperature of 10.5 degrees C during April 2018. Infected fish exhibited whitish-yellow colour formation on the head, dark coloration, degeneration of the operculum, swelling of the gills and fusion of secondary lamellae, erosive lesions on the base of dorsal fins and small ulcers under the dorsal fin, and haemorrhage of the base of fins. Internally, the fish exhibited a distended stomach with transparent fluid, ascites, discoloured liver, spleen and kidney. Samples from the kidney and liver were streaked onto trypticase soy agar plates and were incubated at 22 degrees C for 48 h. Four isolates were obtained from sick fish. Gram staining was performed on the isolates and all were observed as yeast based on cellular morphology using light microscopy. Furthermore, ITS (Internal transcribed spacer) region of strain SM007 (representative strain) was sequenced and showed 100% similarity with multiple GenBank accessions of C. sake sequences. Histopathologic examination revealed necrotic and inflammatory changes in liver and kidney tissue in both natural and experimental infections. In addition, Grocott Hexamine Silver staining revealed hypha structures belonging to the causative agent, found especially in necrotic areas in liver tissue.