Abstract: Vibrio harveyi, Vibrio parahaemolyticus, Pseudoalteromonas piscicida, Staphylococcus epidermidis and Micrococcus luteus were isolated from the gut of blue swimming crab, Portunus pelagicus captured from Strait of Tebrau Johor Malaysia and studied for pathogenicity against the Zoea-1 (Z1 stage) of P. pelagicus. Pathogenic isolates V. harveyi and P. piscicida resulted in 100% mortality at 106 cfu mL-1 and 105 cfu mL-1 after 24 h and 72 h post dose. Conversely, V. parahaemolyticus produced 100% deaths at inoculation 106 cfu mL-1 after 72 h post dose. Cumulative mortality was observed rising with the increase in dose potency of pathogens. S. epidermidis and M. luteus detected with feeble pathogenic characteristics. The LD50 of V. harveyi was 1.2x103 cfu ML-1 (24 h), V. parahaemolyticus was 9.6x105 cfu mL-1 (72 h), P. piscicida was 9.8x103 cfu mL-1 (24 h) and S. epidermidis was 9.8x105 cfu mL-1 (72 h). The mean differences among various pathogenic doses were statistically significant (p<0.05). Susceptibility tests of total 662 isolates were under taken including V. harveyi (n = 180), V. parahaemolyticus (n = 180) and P. piscicida (n = 119), isolates showed mixed trend as multiple resistance and sensitive to antimicrobial agents tested while S. epidermidis (n = 88) and M. Luteus (n = 95) were sensitive to all antibiotics tested. V. harveyi, V. parahaemolyticus and P. piscicida did not show 100% resistance to any of the antibiotics tested. From the results of 14 antibiotics tested, we observed that the highest frequency of single drug resistance in V. harveyi was Streptomycin (89.44%) and sensitive to chloramphenicol (70.55%). Similarly, the highest frequency of single-drug resistance in V. parahaemolyticus was to kanamycin (92.78%) and sensitive to chloramphenicol (93.33%) and P. piscicida was to penicillin (80.67+19.33% intermediate but no sensitive) and sensitive to gentamicin (98.32%). Infections caused by antibiotic resistant pathogens have serious consequences and therapeutic use of tested antibiotic is questionable in larviculture of P. pelagicus.
A.D. Talpur, A.J. Memon, M.I. Khan, M. Ikhwanuddin, M.M. Danish Daniel and A.B. Abol-Munafi, 2011. Pathogenicity and Antibiotic Sensitivity of Pathogenic Flora Associated with the Gut of Blue Swimming Crab, Portunus pelagicus (Linnaeus, 1857). Journal of Animal and Veterinary Advances, 10: 2106-2119.