Aeromonas salmonicida
Legend:  + = positive > 85%,     - = negative > 85%, d = variable, nd = not determined
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Proteobacteria, Class Gammaproteobacteria, Order Aeromonadales, Family Aeromonadaceae, Genus Aeromonas,
Aeromonas salmonicida
(Lehmann and Neumann 1896) Griffin et al. 1953.
Synonyms:
Bacterium salmonicida Lehmann and Neumann 1896, Bacillus salmonicida (Lehmann and Neumann 1896) Kruse 1896,
Proteus salmonicida
(Lehmann and Neumann 1896) Pribram 1933.
Species has been divided in subspecies:
- Aeromonas salmonicida subsp. achromogenes (Smith 1963) Schubert 1967, synonym: Necromonas achromogenes Smith 1963,
- Aeromonas salmonicida subsp. masoucida Kimura 1969,
- Aeromonas salmonicida subsp. pectinolytica Pavan et al. 2000,
- Aeromonas salmonicida subsp. salmonicida (Lehmann and Neumann 1896) Schubert 1967,
- Aeromonas salmonicida subsp. smithia Austin et al. 1989.
Gram-negative  short rods, pleomorphic to coccoid, occurring singly, in pairs or short chains. Nonmotile, but has been discovered that
do harbor flagellin genes. The presence of a polysaccharide capsule has been reported.
Colonies are pinpoint in size after 18–24 h at 20–22 ºC, but after 2-4 d of incubation
are circular, convex, entire, friable, and 1–2 mm in diameter. Colony pigmentation,
when present, is usually yellowish; absence is indicated by grayish white colony.  
Several subspecies produce a brown, diffusible pigment after 5 days, especially on
media containing tyrosine. At temperatures higher than 22 ºC the intensity of the
pigment decreases and at 32 ºC it is not formed.
Facultatively anaerobic.  Hemolysis on sheep blood agar is variable. Optimum growth
temperature is 22–25 ºC. Maximum growth temperature in nutrient broth is 34.5 ºC.
Although
A. salmonicida was generally considered not to grow above 30 ºC, it may
actually be able to grow at 37 ºC.
Grow on furunculosis agar, TSA, TSB and alkaline peptone water (enrichment
medium for foods investigation). Can grow in nutrient broth with: 0 and 3% NaCl, but
not in the presence of 6, 8, or 10% NaCl. No growth on MacConkey agar.
Isolated from natural waters, aquaculture ponds and from infected fish, particularly in
the kidney. Recently has been recovered in co-culture with purple-pigmented bacteria
from fresh water lake sediment.
Resistant to vibriostatic agent O/129. Plasmids carrying resistance to streptomycin,
chloramphenicol, tetracycline, and sulfathiazole as R factors have been isolated.
Affects various fish species, mainly salmonids, but the atypical forms were found in
cyprinids, marine flatfish, even goldfish. It is the main cause of furunculosis in
salmonids. May produce ulcerative dermatitis,swelling at the vent and in the kidney,
external and internal hemorrhages, muscle hemorrhages, ascitic fluid accumulation,  
liquefaction, and gastroenteritis.
  1. Amy Martin-Carnahan and Samuel W. Joseph 2004. Order XII. Aeromonadales ord. nov. In:  Bergey’s Manual of Systematic
    Bacteriology, Second edition,Vol two, part B, George M. Garrity (Editor-in-Chief), pp. 556-587.
  2. M E Pavan, S L Abbott, J Zorzópulos, and J M Janda. Aeromonas salmonicida subsp. pectinolytica subsp. nov., a new pectinase-
    positive subspecies isolated from a heavily polluted river. Int J Syst Evol Microbiol May 2000 50:1119-24.
  3. Brian Austin, Dawn A. Austin. Bacterial Fish Pathogens. Disease of Farmed and Wild Fish. 5th ed. 2012.
  4. Varpu Hirvela-Koski 2005. FISH PATHOGENS AEROMONAS SALMONICIDA AND RENIBACTERIUM SALMONINARUM:
    DIAGNOSTIC AND EPIDEMIOLOGICAL ASPECTS. Academic dissertation.
Below are the common biochemical characters but many more atypical strains were recently isolated. Also, important variations of
biochemical tests results may appear depending on incubation temperature.

Positive results for catalase, oxidase, nitrates reduction, lipase (corn oil), ONPG and acid production from trehalose.
Negative results for urea hydrolysis, acid production from: D-adonitol, D-arabitol, dulcitol, inositol, melibiose, raffinose, rhamnose and
D-xylose.
Variable results for H
2S production, arginine dihydrolase, indole production, citrate utilization, ornithine decarboxylase, lysine
decarboxylase, gelatin hydrolysis, esculin hydrolysis, acid production from: L-arabinose, D-galactose, D-glucose, mannitol, salicin,
sorbitol and sucrose.

Subsp. pectinolytica has the ability to degrade polypectate.
(c) Costin Stoica
Antibiogram
Encyclopedia
Culture media
Biochemical tests
Stainings
Images
Movies
Articles
Identification
Software
R E G N U M
PROKARYOTAE
Previous page
Back
 
Beta
hemolysis
Brown
diffusible
pigment
Motility
Indole
production
Arginine
dihydrolase
Esculin
hydrolysis
Lysine
decarboxylase
salmonicida
+
+
-
-
d
+
d
achromogenes
-
d
-
+
+
-
-
masoucida
+
-
-
+
+
+
+
pectinolytica
d
+
-
+
d
-
-
smithia
-
-
-
-
-
-
-
atypical salmonicida
-
+
-
-
nd
-
-
Differential characters of the Aeromonas salmonicida subspecies:
 
Sucrose
fermentation
Salicin
fermentation
Arbutin
fermentation
D-galactose
fermentation
D-mannitol
fermentation
L-arabinose
fermentation
Sorbitol
fermentation
salmonicida
-
+
+
+
+
+
d
achromogenes
+
-
-
+
-
-
d
masoucida
+
-
-
+
+
+
d
pectinolytica
+
-
nd
nd
+
+
+
smithia
+
-
-
-
-
-
-
atypical salmonicida
+
-
-
+
+
-
nd