479
for 30 min). Type II lacked this inhibition. It was speculated that this thermolabile
agglutination – inhibition antigen corresponds to the so-called K-antigens of coliforms (Nakai et al. 1981 , 1982a ). Molecular traits based on PFGE have revealed
four types among 54 isolates from sea bream in Portugal and Spain (Blanco et al.
2002 ). Results with RAPD revealed two groups related to the host of origin of the
cultures, with most of the isolates from eels in one cluster and the second grouping
comprising isolates from other fi sh species (López-Romalde et al. 2003 ).
From the phenotypic traits, Wakabayashi and Egusa ( 1972 ) concluded that the
causal agent of Sekiten-byo corresponded to a new centre of variation within ‘Group
III’ or ‘Group IV’ of the genus Pseudomonas . This opinion was reached because the
pathogen was Gram-negative, rod-shaped, motile by polarly located fl agella, insensitive to the vibriostatic agent (O/129), and produced catalase and oxidase, but not
acid from glucose or, for that matter, diffusible (fl uorescent) pigment. Because the
strains were dissimilar to other fi sh pathogenic pseudomonads, namely, Ps. fl uorescens , a new taxon was proposed, i.e. Ps. anguilliseptica . We are sceptical about the
validity of this proposal because the description could equally fi t Alcaligenes or
Deleya as well as Pseudomonas (See Cowan 1974 ; Kersters and De Ley 1984 ;
Palleroni 2005 ). In some respects, the G + C ratio and the inability to produce acid
in peptone water sugars is more conducive to the concept of Alcaligenes or Deleya ,
although the pathogen is clearly distinct from existing nomenspecies (Kersters and
De Ley 1984 ). Moreover, it may not be ruled out that the causal agent of Sekitenbyo should be classifi ed in a newly described genus. Certainly, the distinctive micromorphology adds weight to this supposition. Maybe this explains the pronounced
dissimilarity of Ps. anguilliseptica to other species of Pseudomonas as revealed by
analyses of fatty acids and outer-membrane proteins (Nakajima et al. 1983 ).
Diagnosis
Phenotypic Methods Wakabayashi and Egusa ( 1972 ) proposed an identifi cation
scheme for Ps. anguilliseptica based on a small number of phenotypic traits, principally motility, growth at 37 °C, presence of soluble pigment, production of H 2 S,
indole and oxidase, nitrate reduction, gelatin degradation, susceptibility to the vibriostatic agent (O/129), and the ability to attack glucose. According to these workers, the tests were suffi cient to differentiate Ps. anguilliseptica from Ps. fl uorescens ,
Ps. alcaligenes , V. anguillarum , Aer. liquefaciens (= Aer. hydrophila ), Ph. damselae
subsp. piscicida and H. piscium . By API 20 E, T. maritimum and Ps. anguilliseptica
may be indistinguishable.
Serology Ps. anguilliseptica may be rapidly diagnosed by slide agglutination.
However, slight cross-reactions may also occur with other organisms, including Ps.
putida and V. anguillarum , but these interfering cross-agglutinations may be effectively eliminated by using diluted antiserum (Nakai et al. 1981 ).
Pseudomonas anguilliseptica
for 30 min). Type II lacked this inhibition. It was speculated that this thermolabile
agglutination – inhibition antigen corresponds to the so-called K-antigens of coliforms (Nakai et al. 1981 , 1982a ). Molecular traits based on PFGE have revealed
four types among 54 isolates from sea bream in Portugal and Spain (Blanco et al.
2002 ). Results with RAPD revealed two groups related to the host of origin of the
cultures, with most of the isolates from eels in one cluster and the second grouping
comprising isolates from other fi sh species (López-Romalde et al. 2003 ).
From the phenotypic traits, Wakabayashi and Egusa ( 1972 ) concluded that the
causal agent of Sekiten-byo corresponded to a new centre of variation within ‘Group
III’ or ‘Group IV’ of the genus Pseudomonas . This opinion was reached because the
pathogen was Gram-negative, rod-shaped, motile by polarly located fl agella, insensitive to the vibriostatic agent (O/129), and produced catalase and oxidase, but not
acid from glucose or, for that matter, diffusible (fl uorescent) pigment. Because the
strains were dissimilar to other fi sh pathogenic pseudomonads, namely, Ps. fl uorescens , a new taxon was proposed, i.e. Ps. anguilliseptica . We are sceptical about the
validity of this proposal because the description could equally fi t Alcaligenes or
Deleya as well as Pseudomonas (See Cowan 1974 ; Kersters and De Ley 1984 ;
Palleroni 2005 ). In some respects, the G + C ratio and the inability to produce acid
in peptone water sugars is more conducive to the concept of Alcaligenes or Deleya ,
although the pathogen is clearly distinct from existing nomenspecies (Kersters and
De Ley 1984 ). Moreover, it may not be ruled out that the causal agent of Sekitenbyo should be classifi ed in a newly described genus. Certainly, the distinctive micromorphology adds weight to this supposition. Maybe this explains the pronounced
dissimilarity of Ps. anguilliseptica to other species of Pseudomonas as revealed by
analyses of fatty acids and outer-membrane proteins (Nakajima et al. 1983 ).
Diagnosis
Phenotypic Methods Wakabayashi and Egusa ( 1972 ) proposed an identifi cation
scheme for Ps. anguilliseptica based on a small number of phenotypic traits, principally motility, growth at 37 °C, presence of soluble pigment, production of H 2 S,
indole and oxidase, nitrate reduction, gelatin degradation, susceptibility to the vibriostatic agent (O/129), and the ability to attack glucose. According to these workers, the tests were suffi cient to differentiate Ps. anguilliseptica from Ps. fl uorescens ,
Ps. alcaligenes , V. anguillarum , Aer. liquefaciens (= Aer. hydrophila ), Ph. damselae
subsp. piscicida and H. piscium . By API 20 E, T. maritimum and Ps. anguilliseptica
may be indistinguishable.
Serology Ps. anguilliseptica may be rapidly diagnosed by slide agglutination.
However, slight cross-reactions may also occur with other organisms, including Ps.
putida and V. anguillarum , but these interfering cross-agglutinations may be effectively eliminated by using diluted antiserum (Nakai et al. 1981 ).
Pseudomonas anguilliseptica