Tenacibaculosis_ A Comprehensive Overview.pdf

Enrofloxacin was used, but a rapid The taxonomy of the causative agent was appearance of resistant strains was...

Enrofloxacin was used, but a rapid The taxonomy of the causative agent was appearance of resistant strains was a matter of controversy for decades, until evidenced. it was clarified by Suzuki et al. in 2001. Florfenicol has proven to be the best T. maritimum compound in recent years to arrest mortalities. T. soleae Chemotherapy: The Tenacibaculum species recovered Resistance to colistin, kanamycin, Taxonomy and Susceptible from marine fish include: T. discolor neomycin, and the quinolones (oxolinic Hosts acid and flumequine) has been observed. T. dicentrarchi Control and Prophylactic Oral treatments were not effective, but Treatments T. gallaicum immersion treatments were. From the author's experience, only T. Hydrogen peroxide (H2O2): 240 ppm/30 maritimum and T. soleae have the capacity min of H2O2 is necessary to kill T. to produce a systemic infection and can be maritimum when it is colonizing the skin recovered from internal organs. Freshbut mucus, water thisbaths: Preliminary high concentration experiments increases indicated the stress that level of a decrease the fish. in Prophylactic treatments: salinity to 5 ppt for at least 24 Therefore, it is used for treating the h can be a usefulofstrategy surface to reduce tanks before the prevalence the introduction of of T. the fish.maritimum in the farm. Skin ulcers Eroded mouth Adherence: T. maritimum produces The external signs of Tenacibaculosis (T. capsular material, a galactosamine glycan, maritimum) include: Frayed fins which is the first step of the infection. External Signs of Marine Tail rot Quorum-sensing system: This cell-cell Tenacibaculosis communication system regulates the expression of genes involved in virulence Gill necrosis factors, such as the production of exoenzymes. The specific signs may vary depending on the fish species and age. Secretion of enzymes: Extracellular enzymes, such as proteases and chondroitinase, contribute to the colonization and invasion. Virulence-Associated Factors T. maritimum in Turbot (Scophthalmus maximus) High-affinity iron-uptake mechanisms: One involving the synthesis of T. maritimum in Sea bass (Dicenthrarchus siderophores and another that allows the labrax) utilization of heme groups as iron sources Tenacibaculosis in Different by direct binding. Fish Species T. maritimum in Sole (Solea senegalensis) The virulence factors enable T. maritimum In some cases, a mixed infection of T. to overcome the cellular immune response, maritimum and Aeromonas salmonicida induce cell necrosis, delay mucosal was diagnosed. immunity, and change the glycosylation pattern, leading to septicemia and disease Tenacibaculosis in Atlantic Salmon in induction. Northwest, Spain (first isolations in the In some cases, a mixed infection of T. 1990 decade) maritimum and Vibrio anguillarum O1 was present, with the systemic infection of V. anguillarum causing an inhibition in the growth of T. maritimum, making it difficult to recover from internal organs. T. maritimum is an antigenically heterogeneous species, with three O Tenacibaculosis: A Comprehensive serotypes described in marine fish. There is no strict host specificity, and a continuous monitoring of the serotypes of Overview Tenacibaculum is a fastidious, filamentous (5-40 μm), gliding bacterium. the strains isolated in each fish species in a zone over time is recommended. In older liquid and solid media, the cells tend to become spherical, spore-forming The Marine Agar is not useful to (polymorphism). distinguish T. maritimum serotypes, while the FMM is the appropriate medium for Serological Studies and this purpose. Virulence Presumptive diagnosis can be made by microscopic examination of abundant long, thin, rod-shaped bacteria in wet mounts or Gram preparations obtained Intraperitoneal injection and 1-2 h from skin lesions and gills. immersion are not successful in inducing Morphological Features and the disease, but prolonged immersion of Bacterial Culture Optimization fish for 18-24 h is an effective model. Obstacles during culture, such as aggregation, fluctuation, and swarming In asymptomatic fish surviving exposure, activity, can hinder bacterial count and the bacteria can be recovered only from challenge procedures. the mucus, supporting the idea that T. maritimum can persist within aquatic environments utilizing mucus as a Optimization of bacterial culture using reservoir in fish hosts. NIS, Tween 80, SDS, and cellulase enzyme revealed bacterial fluctuation. Flasks containing media at a 1:10 ratio with continuous shaking at 100 rpm resulted in All strains produce cytochrome oxidase a high bacterial yield (high absorbance). and catalase. Gelatin is hydrolyzed, but starch, esculin, and chitin are not. All strains give a similar enzymatic profile The pathogen is an obligate marine in the API ZYM System, with all enzymes microorganism that does not grow on related to the metabolism of media prepared only with NaCl. carbohydrates being absent. The bacterium is mesophilic and grows The phenotypic characterization does not well at temperatures ranging from 15 to allow the differentiation of T. maritimum 34°C. from the other Tenacibaculum species Phenotypic Characterization associated with fish diseases. and PCR Detection The colonies absorb Congo red but do not contain cell wall-associated flexirubin- Specific PCR is necessary for an accurate Bacterial Growth Requirements type pigment, which is a point of diagnosis (primers MAR1/MAR2, Toyama and Identification differentiation. et al.). Marine Agar and FMM (Flexibacter Detection of T. maritimum in internal maritimum medium) are the most organs indicates the ability of the appropriate for the successful isolation of pathogen to proliferate and produce this pathogen. enzymes once it reaches the dermis, leading to a systemic infection. FMM allows better recognition of the typical colonies of this species: flat, pale- yellow with rhizoid edges and strongly adherent to the medium.