If this is indeed Flavobacterium columnare (formerly known as Flexibacter columnaris), then Furan2 and Kanaplex should get the job done. Problem with this type bacteria is there are several strains that have been identified over the years, and they don't all act in the exact same manner, or in the case of medication possibly react in the exact same manner. And of course your fishes immune system has to do its part as well.
But I'm certainly no expert, and I honestly can't say with any real certainty exactly what that is? I could supply you with some links to some past discussions on flexibacter but search is still down. If this is flavobacterium columnare, the leading expert on this particular bacteria and its treatment is A. Decostere.
Below is some info that I posted on this disease in the past. Hopefully it helps.
The problem with Flavobacterium columnare is that there are numerous strains of this bacteria, and to date there is still not a clear understanding regarding the pathogenesis of this disease. So while one form or method of treatment may work for one person, for the next it may already be too late to even begin treatment. Age of the fish, overall immune function, overall environmental conditions, stage of the infection, etc-etc, also all play a role in how a sick fish will react to medication & potential recovery.
The following study is the most detailed work that has been performed to date, by actual accredited published researchers in this field.
Characterization of four Flavobacterium columnare (Flexibacter columnaris) strains isolated from tropical fish.
Decostere A, Haesebrouck F, Devriese LA.
SourceLaboratory of Veterinary Bacteriology and Mycology, University of Gent, Merelbeke, Belgium.
Abstract
Four Flavobacterium columnare strains (AJS 1-4) were isolated from black mollies (Poecilia sphenops) and platies (Xiphophorus maculatus), showing white spots on the back, head and skin ulcers. The isolates developed characteristic rhizoid yellow pigmented colonies on Shieh agar and typical growth in Shieh broth. They were Gram-negative, filamentous bacteria exhibiting flexing movements. When compared to F. columnare strains isolated from temperate fish, it was noted that the four strains originating from tropical aquarium fish are more capable of growing at higher temperatures, the opposite being true for the strains isolated from temperate fish. Biochemical characterization and agglutination tests proved that the isolated strains could be classified as F. columnare. Low minimal inhibitory concentration (MIC) values were found for chloramphenicol, erythromycin, furazolidone, kanamycin, lincomycin, nalidixic acid, oxytetracycline and streptomycin. MIC values were high for colistin, sulfamethoxazole and neomycin. Pathogenicity studies were performed on black mollies. When these animals were submersed in an infective solution of the F. columnare strains, a marked difference in virulence was noted among the four isolated strains, strain AJS 1 being the most virulent one and strain AJS 4 being of low virulence.
Annemie Decostere is one of the lead researchers in the world on this subject, has been published several times, and been referenced scores of times in numerous papers on this particular disease. The following paper, also co-authored by Decostere, was published last year.
http://download.springer.com/static...959_14dd774c9ec27d8fca3e1643b116da89&ext=.pdf
Columnaris disease in fish: a review with emphasis on bacterium-host interactions
Abstract
Flavobacterium columnare (F. columnare) is the causative agent of columnaris disease. This bacterium affects both cultured and wild freshwater fish including many susceptible commercially important fish species. F. columnare infections may result in skin lesions, fin erosion and gill necrosis, with a high degree of mortality, leading to severe economic losses. Especially in the last decade, various research groups have performed studies aimed at elucidating the pathogenesis of columnaris disease, leading to significant progress in defining the complex interactions between the organism and its host. Despite these efforts, the pathogenesis of columnaris disease hitherto largely remains unclear, compromising the further development of efficient curative and preventive measures to combat this disease. Besides elaborating on the agent and the disease it causes, this review aims to summarize these pathogenesis data emphasizing the areas meriting further investigation.
Biofilm Formation by the Fish Pathogen Flavobacterium columnare: Development and Parameters Affecting Surface Attachment
http://aem.asm.org/content/79/18/5633.full
Abstract:
Flavobacterium columnare is a bacterial fish pathogen that affects many freshwater species worldwide. The natural reservoir of this pathogen is unknown, but its resilience in closed aquaculture systems posits biofilm as the source of contagion for farmed fish. The objectives of this study were (i) to characterize the dynamics of biofilm formation and morphology under static and flow conditions and (ii) to evaluate the effects of temperature, pH, salinity, hardness, and carbohydrates on biofilm formation. Nineteen F. columnare strains, including representatives of all of the defined genetic groups (genomovars), were compared in this study. The structure of biofilm was characterized by light microscopy, confocal laser scanning microscopy, and scanning electron microscopy. F. columnare was able to attach to and colonize inert surfaces by producing biofilm. Surface colonization started within 6 h postinoculation, and microcolonies were observed within 24 h. Extracellular polysaccharide substances and water channels were observed in mature biofilms (24 to 48 h). A similar time course was observed when F. columnare formed biofilm in microfluidic chambers under flow conditions. The virulence potential of biofilm was confirmed by cutaneous inoculation of channel catfish fingerlings with mature biofilm. Several physicochemical parameters modulate attachment to surfaces, with the largest influence being exerted by hardness, salinity, and the presence of mannose. Maintenance of hardness and salinity values within certain ranges could prevent biofilm formation by F. columnare in aquaculture systems.
Also from this study .............
The results obtained in this study describe for the first time the formation of biofilm by the fish pathogen F. columnare under both static and flow conditions. Mature biofilms were characterized by presenting complex three-dimensional structures with water channels and abundant EPS similar to those of other Gram-negative bacteria (33, 54). SEM observations were affected by the sample preparation methods used, which should be taken into account in future studies. An important outcome of this study is that F. columnare retained its virulence in biofilms. Therefore, best-management practices in aquaculture facilities should avoid the water quality parameters identified in this study as biofilm promoters. High temperature (>28°C) and high salinity (>5 ppt NaCl) significantly inhibited biofilm formation and could be used as prophylactic measures. In contrast, high hardness (360 ppm) had a striking positive effect on biofilm formation; therefore, the use of lower water hardness is recommended to prevent columnaris disease. All of these parameters, temperature, salinity, and water hardness, are difficult to control in commercial catfish ponds but can be maintained in hatcheries, in which columnaris disease can cause more than 90% mortality in catfish fingerlings (4). Although further studies are needed to assess if F. columnare persists as biofilm in aquaculture settings, our study provides the baseline to determine the effects that temperature, salinity, and hardness will have in a commercial operation.
Probiotics appear to be a promising way in the prevention of different bacterial diseases in aquaculture [122].
Agreed, you can read more about competitive exclusion and probiotics in the sticky posted in the diseases and health section.
Good luck, I hope that helps!
