PhD Thesis
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ِAhmed Mohamed El-Refaee, Ahmed Mahmoud El-Ashram,
2005
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This investigation applied on 1200 fishes (600 O. niloticus and 600 C. garepinus), these fishes submitted to clinical and post-mortem examination and showing clinical and pathological changes in behavior and tissues.
The results of bacteriological examination revealed the presence of 268 Streptococcal species isolates. The prevalence was 22.33 %.
Streptococcal infection for O. niloticus and C. gariepinus was highest in summer and lowest in winter. Streptococcus spp., were highest in Kafr El-Sheikh and lowest in Sharkia. And for C. gariepinus were highest in Kafr El-Sheikh and lowest Domyata governorates in Egypt.
Bacteriological and API-20 examination revealed the isolation of 268 different bacterial isolates. Isolates were isolated from kidney, liver, ascetic fluid, intestine and spleen. The bacterial isolates were identified as 5 species Streptococcus faecium (42.9%), Streptococcus faecalis (29.48%), Streptococcus sp1. (11.57%), Streptococcus sp2 (8.96%) and Streptococcus sp3 (7.09%).
Experimental injection of fish revealed that there is no difference in susceptibility between normal tilapia and monosex tilapia. The histopathological examinations revealed that there were degenerative changes in different organs.
Antibacterial sensitivity testes revealed that there were differences between strains in the sensitivity against different antibacterial discs.
Analysis of proteins of the isolated Streptococcus spp. revealed presence of common characteristics bands (18 and 35KD) which characteristics to Streptococcus spp. and Enterococcus faecalis.
The tree for RAPD-PCR that resulted from cluster analysis noticed that there were two main groups (standard Streptococcus faecalis and Streptococcus faecalis) as one group, and Streptococcus sp.2 and Streptococcus sp.3 as a second group, while the Streptococcus faecium branched to one subgroup from the Streptococcus sp.2 and Streptococcus sp3 group. But the Streptococcus sp.1 presented as out-group.
RAPD-PCR analysis revealed that seven primer out of ten primers yielded number of polymorphic and share bands and three primers failed to give shared bands. 65 DNA bands were detected, 11 shard bands.
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