Hi everybody! I have an answer to one of the many questions from Dolores. Some T. maritimum strains do display different colony morphology on marine agar 2216 (Difco). While most colonies are flat, with irregular to rhizoid edges, mucoid consistency, sticky and very adherent to the agar, creamy white to very pale yellow, some other colony types may appear on the same plate, usually smaller colonies with a raised center, like a wart. You may feel like the culture is not pure, but it actually is; upon subcultivation, each colony yields a mix of colony types. I have no experience of FMM, so I cannot compare colony morphology on this medium with marine agar 2216.

Dear Dolores,

Just few comments regarding your questions:

Some recent work seems to give some indications that the Tenacibaculum strains are capable of biofilm production (in that work it was Tenacibaculum dicentrarchi (Master thesis of Oyro / 2018) But for various reasons I will not recommend using Chlorine for disinfection. Chlorine activity reduce at pH higher than 7.5 which is the case in seawater usually, in presence of organic material which is also often the case in RAS system even after a good sanitizing. To be efficient the system should be first clean and then disinfected with caustic soda (Ph 12 with a circulating solution at 2% of commercial caustic soda for 6 to 12h) Other bactericid product can be applied as well (including quaternary ammonium + glutaral) 

TM will survive in open flow system unless efficient cleaning and disinfection are applied as said previously. It is more difficult to remove them completely from RAS system as disinfection need to be done in place on part of the system and unless you proceed with a dry out period, the biofilter always remain a difficult part to control. Disinfection in place is done with circulating solution of sanitizer and then disinfectant.  

 The reservoir of the pathogen is not always in the culture system; it can be eventually in the inlet system (piping systems  which are often forgotten during C&D procedures) Another solution in the future could be to use barrier flora (inoculation in the system) after disinfection to limit re colonisation of the biofilm by Tenacibaculum strains.  This has been tested for Flavobacterium in fresh water system with trout and has demonstrated some efficiency, reducing the risk if recurrent outbreak and need of therapy. 

I agree with you Snjezana; the oxydative property of H²O² ill initially reduce the quantity of bacteria in the system and on the lesions but correlatively will deteriorate the mucus layer. Repeated treatment will remove part of the mucus leaving the derm unprotected against stressors. To avoid that, Mano oligo saccharides (such as Yang - Sanostan..) can be fed to the fish. They increase the secretion of mucus and limit the secondary effect of H²O². 

Hovewer peroxyde can be used for disinfection in place. inthat case,it is adviced to use stabilised peroxyde.

Hello to all and thank you for that interesting information and comments.

I wanted to add in your conversation that n Greece there was a very interesting PhD by E. Gourzioti who compared the use of different media such as FMM, marine agar and AO and she reports that the best media is FMM. She also reports that during her research she never isolated the bacteria from internal organs. 

Tenecibaculosis in Greece is for me the most important disease of sea bass fry during the first weeks after they are transferred in the sea from the hatcheries.  Almost a week after, you expect the first mortalities which are accompanied by white coloration of the nose and mouth when fish are observed when still being in the water. The other important finding is gill necrosis which leads to mortalities as I can conclude. I always sample the head kidney also and I can say that I dont believe that there is any specific correlation to tenecibaculosis and other bacteria such as vibrio or photobacterium.

A critical parameter is temperature. The disease is found during Spring and Autumn when the temperature rises or falls.  I seldom find it during Summer when the temperature is high and stable. 

What the farmers did and surprisingly works is formalin baths, but I don't advise them to use them similarly to what Snjezana already commented about H2O2 baths. 

In antibiograms they are almost all the time sensitive to Flumequine and SXT but I believe that in the field, SXT works better.  

Thank you again for the information about identification and characterisation.

Regards

Konstantina Bitchava

Nice to share your experience with us Konstantina. Is this research published or should be found somewhere on the web? What identification methods do you use excluding stained smears?

Thank you Snjezana

this is the doi of the publication.  Veterinary Record doi: 10.1136/vr.100778

Fantastic. I am sure it'll be of use.