ENTEROTOXIGENICITY, HEMOLYTIC-ACTIVITY AND ANTIBIOTIC-RESISTANCE OF AEROMONAS SPP ISOLATED FROM FRESH-WATER PRAWN MARKETED IN DHAKA, BANGLADESH

Aeromonas spp. were isolated from gills, swimmerets, eggs, stomachs an d ventral muscles of freshwater prawns (Macrobrachium malcolmsonii) av ailable in the local fish market of Dhaka, Bangladesh. The density of Aeromonas spp. on these different body parts of the prawn samples rang ed from 1.1 0.2 X 10(4) to 1.5 +/-0.16 x 10(7) cfu per gram. The viabl e counts of aeromonads, fecal coliforms (FC) and Escherichia coli grad ually increased in prawn samples when stored at 4 C. At - 20 C, the vi able counts gradually decreased and became zero on the 12th day of sto rage. The isolation of A. sobria (56%) was more frequent than that of A. hydrophila (31%) and A. caviae (13%). In the rabbit ileal loop (RIL ) model, fluid accumulation induced by live cultures and cell-free cul ture filtrates of 11 strains ranged from 0.5 to 1.5 and 0.5 to 1.7 ml/ cm of gut, respectively. Of 11 enterotoxigenic strains, 7 were A. sobr ia and 4 were A. hydrophila. Enterotoxigenicity correlated with hemoly tic activity on blood agar. All enterotoxigenic strains were uniformly sensitive to chloramphenicol and gentamicin and resistant to novobioc in and vancomycin. Isolation of enterotoxigenic and antibiotic-resista nt Aeromonas from these prawn samples indicates possible public health problems for their handlers as well for raw prawn consumers.