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Infection with <i>Mycobacterium pseudoshottsii</i> in Cultured Yellowtail <i>Seriola quinqueradiata</i> in Owase Bay, Japan

2022; Japanese Society of Fish Pathology; Volume: 57; Issue: 2 Linguagem: Inglês

10.3147/jsfp.57.35

1881-7335

Megumi Matsumoto, Yuichiro Machida, Motohisa Kanemaru, Masato Yamamoto, Motohiko Sano, Goshi Kato,

Myxozoan Parasites in Aquatic Species

Mycobacteriosis causes serious economic damages to yellowtail aquaculture in Japan. ​From October to November 2020, mycobacteriosis occurred in yellowtail cultured in Owase Bay, Mie Prefecture, Japan. ​In this study, we observed the gross pathology and histopathology of the diseased fish. ​We identified mycobacteria isolated from the diseased fish and investigated their drug sensitivities against 12 antimicrobial agents. ​Diseased yellowtail exhibited abdominal swelling and many nodules in their kidney and spleen. ​The head kidney and trunk kidney presented typical granulomas with a necrotic core surrounded by epithelioid cells and fibroblasts. ​The isolates were identified as Mycobacterium pseudoshottsii based on phylogenetic analysis using the 16S rRNA gene, hsp65 and rpoB. ​Low concentrations of amikacin, ciprofloxacin, kanamycin and lincomycin inhibited growth of the isolates. ​Two of three isolates showed sensitivity to erythromycin; the other isolate was resistant to it. ​Erythromycin and lincomycin that are permitted for therapeutic use in Perciformes in Japan may be useful for treating yellowtail infected with M. pseudoshottsii. ​However, emergence of antibiotic-resistant strains of M. pseudoshottsii due to antibiotic use requires attention in yellowtail aquaculture.