Lesional patterns associated with mycobacteriosis in an Atlantic horse mackerel, Trachurus trachurus (L.), aquarium population
Investigación publicada en Journal of Fish Diseases
1 de junio de 2014
Mycobacteria are ubiquitous bacteria in the environment, particularly in aquatic reservoirs. They are responsible for a chronic or acute systemic granulomatous disease, named mycobacteriosis, which occurs in wild, aquarium and culture fish (Jacobs et al. 2009). Three Mycobacterium spp. have dominated the literature on fish diseases: Mycobacterium marinum, Mycobacterium fortuitum and Mycobacterium chelonae (Gauthier & Rhodes 2009). Generally, mycobacteriosis in fish displays granulomas produced in multiple organs or tissues, although chronic disease may not produce clinical signs (Gauthier & Rhodes 2009). Although mycobacteriosis has been described in numerous fish species (Nigrelli & Vogel 1963), including freshwater and marine fish from tropical to subarctic latitudes (Gauthier & Rhodes 2009), to the best of the authors` knowledge, information about this disease in Atlantic horse mackerel, Trachurus trachurus (L.) is not available.
The objectives of this work were to (i) provide a detailed description and prevalence of lesions compatible with mycobacteriosis infections in an aquarium Atlantic horse mackerel population and (ii) identify the aetiological agents isolated from different lesions.To evaluate the health status of an Atlantic horse mackerel population living in a 550 000-L tank, 103 fish weighing 90–764 g were randomly caught. All fish were humanely killed by trans-spinal dissection after immersion in a 100 ppm tricaine methanesulfonate (MS-222) anaesthetic bath. A complete necropsy was performed, and samples from eyes, gills, heart, stomach, intestines, liver, spleen, kidney and coelomic fat were collected. They were fixed in 10% neutral buffered formalin, processed routinely and stained with haematoxylin and eosin (H&E) and Ziehl–Neelsen (ZN). Spleen, kidney and liver samples with different kinds of granulomatous lesions from 14 selected fish were cultured. The tissue samples from each animal were pooled, homogenized in sterile distilled water, decontaminated with 0.37% hexadecylpyridinium chloride for 30 min (Corner & Trajstman 1988) and centrifuged at 1500 g for 30 min. Sediments were cultured onto the pyruvate-enriched Löwenstein–Jensen, Coletsos and Middlebrook 7H11 media (Difco FSM) at 19 °C.Isolates of Mycobacterium species were identified by amplification and sequence analysis of the 16S rRNA and the hsp65 genes according to PCR conditions previously described (Böddinghaus et al. 1990; Telenti et al. 1993). Forty-five of the 103 fish presented gross lesions that were consistent with mycobacteriosis. Thirteen of 45 fish presented two or more affected organs. Lesions were characterized by the presence of coalescent multifocal black or white pinpoints (less than 1 mm of diameter) in different tissues (liver: 22; coelomic fat: 16; digestive tract: 17; spleen: 7; swim bladder: 2; kidney: 1; and brain: 1) (Fig. 1). Additionally, ocular globes showed ulcerative corneal lesions in 22 cases (six right, 16 left), and 18 animals presented nodular lesions in the inferior mandible (ulcerated in nine cases)
Ortega Jo., Noguera A., Garcia-Quiros A., Viana D., Selva L., de Juan L., Romero B., Garcia-Parraga D., Crespo JL. y Corpa JM.
 | Facultad de Veterinaria. Universidad CEU Cardenal Herrera (CEU-UCH). |
 | Servicio de Micobacterias (MYC). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM). |
| Piscifactorías Andaluzas, S.A.. | |
 | Oceanogràfic. Generalitat Valenciana. |
| Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM). |
