529
spreading, and has certainly reached Atlantic salmon production in Chile where it
has caused losses (Silva-Rubio et al. 2008 ).
Diagnosis
Phenotypic Methods Kent ( 1982 ) reported that V. anguillarum produces a characteristic profi le in API 20E, i.e.
v
v
v
whereas Maugeri et al. ( 1983 ) published a slightly different pattern, i.e.
v
v
v v v
v
v
, where ‘v’ indicated a variable result.
Of course, it is necessary to modify the protocol for use with marine bacteria.
Thus, it was essential to suspend cultures in 2–3 % (w/v) saline rather than distilled
water, and the inoculated test strips were incubated at 25 °C (not 37 °C) for up to
48 h. Maugeri et al. ( 1983 ) considered that it was essential to carry out some additional tests with putative V. anguillarum , namely motility and sensitivity to O/129,
in order to confi rm that the isolates, were indeed, motile and were inhibited by the
vibriostatic agent. However, some cultures may be resistant to the action of O/129
(Muroga et al. 1979 ) and appear to be non-motile. The latter phenomenon may
result from exposure to the partial inhibitory activity of some antimicrobial
compounds.
A simplifi ed diagnostic test for V. anguillarum , involving ‘glucose motility
deeps’ (GMD) has been reported (Walters and Plumb 1978 ). Essentially, GMD is a
much modifi ed version of the oxidation-fermentation test medium, comprising:
phenol red broth base (Difco) 1.6 % (w/v)
glucose 1.0 % (w/v)
yeast extract 0.3 % (w/v)
agar 0.3 % (w/v)
Stab-inoculated media are incubated at 25 °C for 24–48 h, when acid production
and motility (indicated as a carrot-like diffuse growth around the stab mark) are
recorded. It remains for further work to confi rm the specifi city of the reaction for V.
anguillarum.
Serology An interesting development concerns the detection of a thermolabile V.
anguillarum O-antigen, termed the k-1 antigen by slide agglutination (Tajima et al.
1987 ). So far, the data indicate that this antigen is specifi c to V. anguillarum.
Molecular Methods Molecular methods have been invoked to improve the identifi cation of V. anguillarum. Using partial 16S rRNA sequences, a specifi c 16S rRNA
oligonucleotide probe detected a minimum of 5 × 10
3 cells/ml in culture or tissue
extracts (Rehnstam et al. 1989 ). Detection of 1–10 bacterial cells in culture or
Vibrio anguillarum
spreading, and has certainly reached Atlantic salmon production in Chile where it
has caused losses (Silva-Rubio et al. 2008 ).
Diagnosis
Phenotypic Methods Kent ( 1982 ) reported that V. anguillarum produces a characteristic profi le in API 20E, i.e.
v
v
v
whereas Maugeri et al. ( 1983 ) published a slightly different pattern, i.e.
v
v
v v v
v
v
, where ‘v’ indicated a variable result.
Of course, it is necessary to modify the protocol for use with marine bacteria.
Thus, it was essential to suspend cultures in 2–3 % (w/v) saline rather than distilled
water, and the inoculated test strips were incubated at 25 °C (not 37 °C) for up to
48 h. Maugeri et al. ( 1983 ) considered that it was essential to carry out some additional tests with putative V. anguillarum , namely motility and sensitivity to O/129,
in order to confi rm that the isolates, were indeed, motile and were inhibited by the
vibriostatic agent. However, some cultures may be resistant to the action of O/129
(Muroga et al. 1979 ) and appear to be non-motile. The latter phenomenon may
result from exposure to the partial inhibitory activity of some antimicrobial
compounds.
A simplifi ed diagnostic test for V. anguillarum , involving ‘glucose motility
deeps’ (GMD) has been reported (Walters and Plumb 1978 ). Essentially, GMD is a
much modifi ed version of the oxidation-fermentation test medium, comprising:
phenol red broth base (Difco) 1.6 % (w/v)
glucose 1.0 % (w/v)
yeast extract 0.3 % (w/v)
agar 0.3 % (w/v)
Stab-inoculated media are incubated at 25 °C for 24–48 h, when acid production
and motility (indicated as a carrot-like diffuse growth around the stab mark) are
recorded. It remains for further work to confi rm the specifi city of the reaction for V.
anguillarum.
Serology An interesting development concerns the detection of a thermolabile V.
anguillarum O-antigen, termed the k-1 antigen by slide agglutination (Tajima et al.
1987 ). So far, the data indicate that this antigen is specifi c to V. anguillarum.
Molecular Methods Molecular methods have been invoked to improve the identifi cation of V. anguillarum. Using partial 16S rRNA sequences, a specifi c 16S rRNA
oligonucleotide probe detected a minimum of 5 × 10
3 cells/ml in culture or tissue
extracts (Rehnstam et al. 1989 ). Detection of 1–10 bacterial cells in culture or
Vibrio anguillarum