First evidence of fish nocardiosis in Mexico caused by Nocardia seriolae in farmed red drum (Sciaenops ocellatus, Linnaeus)

Abstract

Between August and December 2013, the offshore cages of a commercial marine farm culturing red drum Sciaenops ocellatus in Campeche Bay Mexico were affected by an outbreak of an ulcerative granulomatous disease with up to 70% cumulative mortality. Thirty‐one adults displaying open ulcers on the skin were submitted for diagnosis. At necropsy, multiple white‐yellowish nodules (0.1–0.5 cm in diameter) were present in all internal organs, where the kidney and the spleen were the most severely affected. Histopathology evinced typical systemic granulomatous formations. Gram and Ziehl–Neelsen stains on tissue imprints, bacterial swabs and tissue sections revealed Gram‐positive, acid‐fast, branching beaded long rod filamentous bacteria. Tissue samples resulted positive for nocardiosis with a Nocardia genus‐specific nested PCR. Definite identification at the species level and taxonomic positioning of the fastidious pathogen were achieved through a specific Nocardia seriolae PCR and by sequencing the gyrB gene of pure isolates. After administration of antibiotics during fry production, a posterior follow‐up monitoring (from 2014 to 2017) detected mild but recurrent outbreaks of the bacteria with no seasonality pattern. To the extent of our knowledge, this is the first report of piscine nocardiosis in Mexico and the first time this disease is detected in red drum.

Infectious diseases reported in warm‐water marine fish cage culture in East and Southeast Asia—A systematic review

“…could be a source of pathogen introduction to saltwater aquaculture facilities. Furthermore, poor nutritional status is predicted to predispose fish to this bacterial infection (del Rio‐Rodriguez et al, 2021; Elkesh et al, 2013).…”

Comparative genomics of Nocardia seriolae reveals recent importation and subsequent widespread dissemination in mariculture farms in the South Central Coast region, Vietnam

“…Whilst our results suggest a probable Asian origin for the Vietnamese outbreaks, there are few publicly available N. seriolae genomes (only 20 as of 11 February 2022, including seven from our study), and none from other Asian regions such as Taiwan [20], Singapore, Malaysia, or Indonesia [71], or non-Asian regions such as Mexico [23] and USA [21] where N. seriolae outbreaks have been documented; therefore, the precise origin of the Vietnamese outbreaks and mode of N.…”

“…Nocardiosis has also impacted several other important fish species within the Japanese aquaculture industry such as amberjack (Seriola dumerili), Japanese flounder (Paralichthys olivaceus), and chub mackerel (Scomber japonicas). N. seriolae has subsequently been documented in Taiwan, China, Korea, USA, and Mexico, where high mortalities and associated economic losses due to nocardiosis have been reported in freshwater and marine fish species in both cultured and wild populations [13][14][15][16][17][18][19][20][21][22][23]. Despite causing significant economic losses in fish aquaculture worldwide, there are currently no effective measures against nocardiosis.…”

“… N. seriolae has subsequently been documented in Taiwan, China, Korea, USA, and Mexico, where high mortalities and associated economic losses due to nocardiosis have been reported in freshwater and marine fish species in both cultured and wild populations [13–23]. Despite causing significant economic losses in fish aquaculture worldwide, there are currently no effective measures against nocardiosis.…”

Function and Characterization of an Alanine Dehydrogenase Homolog From Nocardia seriolae

“…The symptoms of diseased fish include skin ulceration and serious sarcoidosis caused by a mass of white nodules in the gills, spleen, liver, head kidney, and trunk kidney (5). According to reports, N. seriolae was able to infect about 42 kinds of marine and freshwater fish, such as blotched snakehead (Channa maculata), amberjack (Seriola dumerili), yellowtail (Seriola quinqueradiata), snubnose pompano (Trachinotus blochii), golden pompano (Trachinotus ovatus), largemouth bass (Micropterus salmoides), large yellow croaker (Larimichthys crocea), and red drum (Sciaenops ocellatus) (3,(6)(7)(8).…”