الفهرس 
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Abstract
In a view of increasing evidence supporting the role of Aeromonas in human disease, we studied the presence of virulence, antibiotic resistance determinants among Aeromonas spp. isolates from fresh water palatable Nile tilapia, Indian ruho carp intended for human consumption in Temsah lake (Egypt), aquaculture ponds in (Egypt) and (India) involved their association with plasmids. Aeromonas hydrophila and Aeromonas sobria were isolated from different organs from Nile tilapia (Oreochromis niloticus) from Temsah lake (94.7%), (1.3%), fish farm in Egypt (100%), none of A. sobia was isolated while from indian ruho carp frys (Labio rohita) in India were (33.3%),(66.7 %) respectively, (ompW, aha1, lip) virulent genes were all common in these strains from ruho carp (75%, 75%, 25%) and lip. gene in A. hydrophila from tilapia (50%) while aerO virulent gene was not found in any of them, Moreover, the isolates showed phenotypic antibiotic resistance to the frequently used antibiotics for human infections in testing the antibiotic sensitivity using disc diffusion method, gentamycin, ciprfloxacin were the drug of choice in combating the bacterial growth in vitro, (100%) sensitivity while ampicillin failed to compate Aeromonas spp. Tetracycline phenotypic resistance was clearly observed in Aeromonas spp. from Carp (28.6%) which confirmed by presence of genomic and plasmid encoded tetA, tetE while tetG was in plasmid DNA only with coexistence of tetA, tetG in the same plasmid, However tetB,C,D were not detected. One to seven resistance plasmids (29/32) were isolated from multi-drug resistance, (16/29) virulent, (13/29) non virulent while (3/32) virulent Aeromonas spp.were not plasmid encoded with a molecular weight ranging from (3.3 kbp to 20 kbp and 1.1-23 kbp) in Aeromonas spp. from tilapia and ruho carp respectively, while all eight isolates were plasmid encoded in ruhocarp. blaTEM-1bwas detected in 15/19 (78.9 %) of the Aeromonas plasmid encoded strains from tilapia, all non virulent strains were blaTEM-1b positive also variable bands of genomic and class I integron encoded plasmid were detected in 16/19 (84.2%) isolates varied from (0.3 - 1.8 kbp) in sizes. This study can be considered as a reference for further studies about this recently introduced veterinary antimicrobial agent.
Key words: Nile tilapia, Aeromonas, virulent, antibiotic resistance, plasmid, classI integron.