PHENOTYPIC CHARACTERIZATION OF BACTERIAL PATHOGENS ASSOCIATED WITH NILE TILAPIA (OREOCHROMIS NILOTICUS) MASS MORTALITIES IN SOME EGYPTIAN FISH FARMS
Ayman A. Ammar; Salh F. Saqr; Mahmoud M. El-Adawy;
Tagreed M. Nageeb; Ahmed M. Abdelwahab and Ahmed A. Ahmed.
Central Laboratory for Aquaculture Research, Agriculture Research Centre Sharkia, Egypt.
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Received 25 /10 /2020 |
Accepted 24 /11 /2020 |
ABSTRACT
The present study was planned to investigate the most bacterial pathogens associated with the Nile tilapia mass mortality in Egyptian fish farms. The studies were carried out onto clinically diseased Nile tilapia collected from 3 localities in Egypt fish farms. Clinical examination revealed darkness of the skin, hemorrhage on the operculum, base of fins around mouth edge and anal opening. The postmortem examination showed congestion of internal organs, liver with necrotic lesion, enlarged with hemorrhagic ends and enlarged gall bladder. A total of 110 bacteriological samples were taken, 50 samples from Kafr El-Sheikh, 25 from El-behera and 35 samples from Sharkia provinces. The results of bacteriological examination revealed the presence of 78.0 bacterial isolates related to 4.0 bacterial species. The most predominant bacterial spp. was A.veronii 27.0 isolates (34.6%) followed by A.hydrophila 22.0 isolates (28.2%), Actinobacter spp.17 isolates (21.8%) and Streptococcus spp 12.0 isolates (15.4%).The distribution of isolates among various examined tissue and organs were; Skin 22.0 (28.2%), gills 18.0 (23.1%), liver 16 (20.5 %), kidney 12 (15.4%) and spleen 10 isolates (12.8 %). The distribution of A.veronii isolates were; skin 6.0 (22.2 %), gills 5.0 (18.5%), liver 4.0 (14.9%), kidney 6.0 (22.2 %) and spleen 6.0 isolates (22.2 %). The distribution of A.hydrophila were skin 5.0 (22.7 %), gills 5.0 (22.7 %), liver 4.0 (18.2 %), kidney 4 (18.2 %) and spleen 4.0 isolates (18.2%). The distribution of streptococcus spp isolates were; skin 4.0 (33.3 %), gills 4 (33.3%), liver 3.0 (25%), kidney 1.0 (8.4%) and spleen 0.0 isolates (0.0%). The distribution of Actinobacter spp. isolates were skin 7.0 (41.2%), gills 4.0 (23.5%), liver 5 (29.4 %), kidney 1.0 (5.9%) and spleen 0.0 isolates (0.0%).
Keywords:
Aeromonas Veronii, Aeromonas hydrophila, streptococcus spp, Actinobacter spp , Nile tilapia.
