VIRULENCE FACTORS AND PATHOGENICITY OF VIBRIO-VULNIFICUS STRAINS ISOLATED FROM SEAFOOD

The virulence factors of Vibrio vulnificus are not yet well understood . So far, many hydrolytic enzymes have been implicated in the pathogen esis of this micro-organism. The present research was carried out in o rder to study the presence of some of these enzymes in 133 V. vulnific us strains isolated from 45 seafood samples. The results showed that 1 00% of these strains were positive for the production of lecithinase a nd lipase (Tween-80), 99.2% for caseinolytic protease, 96.9% for DNase , 65.4% for mucinase and 46.6% for elastase. None of the strains was p ositive for the production of collagenase and 96% were haemolytic agai nst sheep blood cells. In relation to colony morphology on brain heart infusion (BHI) agar and nutrient agar, 59.4% of strains showed opaque morphology on BHI agar and 57.9% on nutrient agar, 10.5% presented tr anslucent morphology on both agars and 30.1 and 31.6% of strains showe d a mixture of opaque and translucent morphology on BHI agar and nutri ent agar, respectively. None of the translucent colonies was virulent to mice. Therefore, opacity was a useful marker for potential virulenc e. Of 45 food samples contaminated with V. vulnificus, 29 (64.4%) pres ented strains lethal to adult mice.