Flavobacterium psychrophilum
| Flavobacterium psychrophilum | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Flavobacterium psychrophilum | ||||||||||||
| ( Bernardet & Grimont 1989) Bernardet et al. 1996 |
Flavobacterium psychrophilum , Syn . : Flexibacter psychrophilus , Flexibacter psychrophila , Cytophaga psychrophila and Flexibacter columnaris , is a fish-pathogenic, ubiquitous , psychrophilic , gram-negative , filamentous, yellow-pigmented bacterium from the Flavobacteriaceae family. F. psychophrilum is not zoonotic .
The bacterium was first described in 1922 by DAVIS in warm water fish from the Mississippi and later known as the cause of columnaris disease (saddleback disease). BORG isolated in 1948 Flavobacterium psychrophilum as Cytophaga psychrophila , describing the bacteria as a cause of in salmonids etiology , occurring cold water disease (Coldwater disease). Flavobacterium psychrophilum is also responsible for the RTFS (Rainbow Trout Fry Syndrome) disease that occurs in the rainbow trout ( Oncorhynchus mykiss ) and in which there is massive death in the fry (TORANZO & BARJA, 1993). F. psychophrilum may be considered a cosmopolitan, since findings in North America, Asia and Europe in a variety of freshwater fish and the like. a. on eels, carp-species , salmonids , esocids and real perches .
etiology
Flavobacterium psychrophilum is a very slender, long 0.5 × 4–12 µm large gram-negative bacterium. When magnified under the microscope, it shows gliding motility and forms characteristic pillars in the mucus of the skin and gills of fish.
Epidemiology
Observations on freshwater fish showed more frequent outbreaks of disease in the higher temperature range. The course of a disease infestation depends on the virulence of the respective bacterial strain as well as on the general condition of the fish. Flavobacterium psychrophilum is considered to be a commensal bacterium, as it has also been detected in healthy fish. The bacteria can survive for a long time in warm, organically polluted water even without a host. In acidic and unpolluted water, however, the survival time drops significantly.
Columnar disease
In the early stages of columnar disease, whitish spots form in the mouth area, the fins and on the edges of the scales. Lesions tend to occur in the head and back of the fish. These whitish to greyish spots are hemorrhagic and are characterized by rapid expansion. The central tissue becomes necrotic and forms deep ulcers extending into the muscles. The edge is colored macroscopically orange, which is caused by the pigment formation of the bacteria. At the edges of these ulcers there is massive inflammation with infiltration by granulocytes and macrophages. A characteristic feature here are the bacteria of F. psychophrilum deposited in columns . If the fins are infected, they begin to decompose from the fin edges to the point where the fin rays are completely exposed. Within the gills, the gill leaves dissolve like a piston from the tip or stick together in juvenile fish due to swelling of the gill arches. A slime build-up also occurs. As a result, the uptake of oxygen is massively hindered, which leads to faster breathing or death. The mortality rate can be up to 90%. There is a chronic and an acute course of columnar disease. In the chronic course of the disease, the whitish-greyish spots spread extremely slowly and the fish only dies after several days. In the acute course, the inflamed spots spread massively within 36 hours. The mortality rate goes up to 50%.
In the brood and juvenile salmonid fish, the disease tends to break out in the head and back area. This fact also led to the designation as "Saddleback Disease". Effective drugs do not currently exist and a causal control is not possible. Vaccinations in Pacific salmon and catfish produced varying degrees of success.
root cause
The main cause of warm water fish is too high a temperature combined with a high germ density (overstocking). Infections with F. psychophrilum are favored by injuries to the epithelium caused by long-term vitamin or nutritional deficiencies. Physicochemical damage caused by high ammonia concentrations, high pH and low oxygen concentrations are also possible triggers of the disease. In general, an outbreak of the disease can be equated with poor water conditions.
treatment
A causally effective control is not possible, as a columnar disease is always associated with poor water quality. Immediate improvement in keeping conditions is essential. With the use of antibiotics, therapeutic effects are often not achieved, but instead often lead to a worsening of the course of the disease. Baths with potassium permanganate or common salt that disinfect the surface may lead to an improvement in the chronic course, as this results in a detachment of the mucus with the bacteria in it. The prescription antibiotics amoxicillin or chloramphenicol can be used to treat acute disease .
swell
- Medical microbiology , infection and epidemic theory by Rolle / Mayr, Enke Verlag, Stuttgart 2007, ISBN 978-3830410607 .
- Fish diseases , Rudolf W. Hoffmann, Eugen Ulmer Verlag, Stuttgart 2005, ISBN 3-8001-2739-3 .
- Diseases in aquarium fish , Dieter Untergasser, Franckh-Kosmos Verlag, 2006, ISBN 3-440-10264-5 .
- Borg, AF (1960): Studies on myxobacteria associated with diseases in salmonid fishes . J Wildl Dis 8, 1-85.
- Toranzo, AE & Barja, JL (1993): Fry mortality syndrome (FMS) in Spain. Isolation of the causative bacterium Flexibacter psychrophilus. Bull Eur Ass Fish Pathol 13, 30-31.
