this area. A scale :' "^ removed, and the exposed surface is sterilized 

 with methylated spirit. The needle is inserted obliquely and pushed 

 upward and inward, care being taken to avoid the ribs^, until it comes 

 in contact mth the vertebral column. It is then withdrawn until it is 

 no longer touching the vertebral column, and then the sample is withdrawn. 

 This is mainly blood, but fragments of renal tissue are often also 

 present. The sample is then spread on nutrient agar medium. 



The Furunculosis Committee in 1933 supplied additional information 

 for the examination of suspected carriers of B. salmonicida . They 

 emphasized that at autopsy, particular care should be taken to cultivate 

 a siifficiently large amount of kidney tissue. After the body of the fish 

 has been opened and the intestine and air bladder dissected away, a 

 stout inoculating loop is drawn several times through the kidney, 

 breaking up the tissue and mixing it, and then several loopfuls are 

 spread on plates of nutrient agar. When a very large trout or salmon is 

 being examined, a scalpel is used for breaking up the tissue. 



The Furunculosis Committee (1933) stated that grovrfch was heavier 

 and more rapid in the presence of tissue fragments or blood. They also 

 stated that the use of fluid media is disadvantageous if the fish has 

 been killed some time before examination, as B, salmonici da grows more 

 slowly than such water organisms that readily invade the blood and 

 kidney shortly after death. 



As mentioned in the section on pigment production, lack of 

 pigment production does not necessarily contraindicate B. salmonicida, 

 in view of the factors (pK, temperature, nature of media, and strain 

 of organism) which may determine the time of appearance, and even the 

 presence or absence, of pigment. However, if extremes of pH are avoided, 

 a solid medium selected and the proper incubation temperature (20° C.) 

 used, the danger of missing B. salmonicida on primary isolation is 

 reduced to a minimvun. 



Two organisms have been reported (Furunculosis Committee 1930) 

 which may be confused mth B. salmonicida ; 



(1) A short. Gram-negative bacillus which in culture produced a brown 

 pigment like that of B. salmonicida . It differed from B. salmonicidc 

 in several respects: 



(a) motility; (b) abundant growth on potato with a glistening, 

 dirty yellow, and later purplish-brown coloration of the upper part 

 of the medium; (c) fermenting sucrose; and (d) nonpathogenicity to 

 frogs. 



(2) A short, nonmctile. Gram-negative bacillus isolated by Lloyd (1929) 

 from sea water. Firth of Clyde, at 37 fathoms (222 feet). It 

 produced a groirth on culture medium which was at first whitish -vidth 

 a bluish or violet tint, but after 15 days yielded a dark brovm 

 coloration of the medium. Unlike B. salmonicida, it did not 



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