113
As a result of pathogenicity experiments with rainbow trout (average weight = 8 g)
maintained in fresh water at 18 °C, it was established that 1.25 × 10
6 cells, administered by i.p. injection, were capable of killing fi sh within a few days (Austin et al.
1985 ). However, it must be emphasised that the status of this organism to fi sh
pathology is uncertain.
Microbacteriaceae Representative
Microbacterium paraoxydans
The organism was recovered from Nile tilapia in Mexico. The disease signs included
lethargy, erratic swimming, melanosis, scale loss, blindness, exophthalmia and/or
red or opaque eyes. Diseased tissues were inoculated onto TSA supplemented with
0.5 % (/v) glucose, BHIA supplemented with 5 % (v/v) sheep blood, MacConkey
agar, glutamate-starch-phenol red agar, and TCBS with incubation at 30 +/− 1 °C
for 24–48 h. Identifi cation was achieved by sequencing of the 16S rRNA gene.
Pathogenicity was confi rmed in laboratory-based infectivity experiments using sole
( Solea vulgaris ) (Soto-Rodriguez et al. 2013 ).
Micrococcaceae Representative
Micrococcus luteus
Characteristics of the Disease
Disease signs were consistent with the notion of RTFS. Thus, moribund fi sh, in the
size range of 0.5–5.0 g, displayed exophthalmia, pale gills, enhanced skin pigmentation and swollen abdomen. Internally, the kidney was swollen, the spleen was pale
and elongated, and some ascitic fl uid was present in the peritoneal cavity (Austin
and Stobie 1992 ).
Isolation
Cultures were recovered following incubation of swabbed material (kidney, spleen
and ascitic fl uid) on skimmed milk agar with incubation at 25 °C for 48–72 h
(Appendix in Chap. 12 ; Austin and Stobie 1992 ).
Micrococcaceae Representative
As a result of pathogenicity experiments with rainbow trout (average weight = 8 g)
maintained in fresh water at 18 °C, it was established that 1.25 × 10
6 cells, administered by i.p. injection, were capable of killing fi sh within a few days (Austin et al.
1985 ). However, it must be emphasised that the status of this organism to fi sh
pathology is uncertain.
Microbacteriaceae Representative
Microbacterium paraoxydans
The organism was recovered from Nile tilapia in Mexico. The disease signs included
lethargy, erratic swimming, melanosis, scale loss, blindness, exophthalmia and/or
red or opaque eyes. Diseased tissues were inoculated onto TSA supplemented with
0.5 % (/v) glucose, BHIA supplemented with 5 % (v/v) sheep blood, MacConkey
agar, glutamate-starch-phenol red agar, and TCBS with incubation at 30 +/− 1 °C
for 24–48 h. Identifi cation was achieved by sequencing of the 16S rRNA gene.
Pathogenicity was confi rmed in laboratory-based infectivity experiments using sole
( Solea vulgaris ) (Soto-Rodriguez et al. 2013 ).
Micrococcaceae Representative
Micrococcus luteus
Characteristics of the Disease
Disease signs were consistent with the notion of RTFS. Thus, moribund fi sh, in the
size range of 0.5–5.0 g, displayed exophthalmia, pale gills, enhanced skin pigmentation and swollen abdomen. Internally, the kidney was swollen, the spleen was pale
and elongated, and some ascitic fl uid was present in the peritoneal cavity (Austin
and Stobie 1992 ).
Isolation
Cultures were recovered following incubation of swabbed material (kidney, spleen
and ascitic fl uid) on skimmed milk agar with incubation at 25 °C for 48–72 h
(Appendix in Chap. 12 ; Austin and Stobie 1992 ).
Micrococcaceae Representative