Isolation characterization, virulence potential ofWeissella cetiresponsible for weissellosis outbreak in rainbow trout (Oncorhynchus mykiss) cultured in Mexico

Abstract

Weissella ceti, a Gram-positive nonmotile bacterium, is currently an emerging pathogen within rainbow trout (Oncorhynchus mykiss) farms in China, Brazil, the United States, and Japan. This study is the first to isolate, identify, and characterize W. ceti isolates from rainbow trout farmed in Mexico. In late 2015, a severe disease outbreak caused a 60% mortality rate among 20,000 fish. The diseased rainbow trout (100-300 g average) exhibited severe cachexia, body darkening, abdominal distension, exophthalmia, haemorrhages, and corneal opacity. Internally, diseased fish had pale gills; multifocal, disseminated whitish spots on the liver; haemorrhages in the swim bladder, ovary, and on the parietal surface of the muscle; and hearts with pseudo-membrane formation. Histologically, lesions were characterized by corneal oedema, degenerative and necrotic hepatitis, and meningitis. A brain (W-1) and kidney (W-2) isolate were identified as W. ceti through polyphasic taxonomy, which included phenotypic characterization and 16S rRNA sequencing. RAPD and ERIC-PCR analyses demonstrated genetic homogeneity among the Mexican isolates. Virulence tests in rainbow trout through intraperitoneal W. ceti injections at concentrations of 1 × 10 , 1 × 10 , and 1 × 10 CFU per fish resulted in cumulative mortality rates of 25%, 62.5%, and 87.5%, respectively, as well as the same clinical signs of hemorrhagic septicaemia as were recorded for the natural outbreak. The present report is the first to confirm the presence of W. ceti in Mexico, thus extending the known geographical distribution of this pathogen across the Americas.

First Identification and Characterization of Lactococcus garvieae Isolated from Rainbow Trout (Oncorhynchus mykiss) Cultured in Mexico

“…Indeed, the only recognized endemic pathogen until 1999 was the infectious pancreatic necrosis virus [ 10 ]. However, intensified aquaculture farming since the late 2000s has resulted in the appearance of diseases, such as the recently confirmed rainbow trout fry syndrome ( Flavobacterium psychrophilum ) [ 11 ] and weissellosis [ 12 ]. The occurrence of infection by Gram-positive microorganisms in rainbow trout has been suspected since 2016, but to date, no cases of streptococcosis or lactococcosis have been officially reported in the country [ 13 ].…”

Enfermedades bacterianas y sus agentes etiológicos identificados en peces de México - Una Revisión

“…El primer reporte de weissellosis se describió en China en 2007 (34), registrando pérdidas de hasta 40% en truchas adultas con signología septicémica. Posteriormente se describió en Brasil (33), también con manifestación septicémica en truchas adultas, y cuadros similares han sido informados en los Estados Unidos de Norteamérica, Japón y Colombia (34,35), México (10), Canadá, Sudáfrica y Perú (35).…”

“…Difundir el estado sanitario de las actividades pecuarias de una región es muy importante ya que la información recaudada de brotes y/o durante vigilancia sirve para identificar riesgos y/o establecer acciones de control (5). En este sentido, algunos estudios independientes sobre la sanidad piscícola de México han descrito aislamiento de bacterias oportunistas (5,6,7), y casos donde se comprobó que las bacterias causaron enfermedad clínica, incluso por bacterias emergentes (3,8,9,10,11). Por su parte, las autoridades sanitarias del país realizan actividades de vigilancia a través de los comités estatales de sanidad acuícola (4,5).…”

O gênero Weissella na indústria de alimentos: Uma revisão

“…Some strains of Weissella such as W. cibaria MG1 (Lynch et al, 2015) and W. cetti (Ortega, et al, 2018) can hydrolyze arginine, which favors its survival in environments where it is subjected to stress. A good example for this is providing a greater amount of ATP when the carbon source is scarce or producing ammonia by protecting from acid stress (Lynch et al, 2015).…”

“…Some EPS that are being produced, such as galactan, has good emulsifying and stabilizing capacities which provides its future use in cosmetic and food emulsions (Ortega, et al, 2018, De Angelis, et al, 2002, Kavitake, Balvan, Devi & Shetty, 2020.…”