Molecular analysis of Vibrio vulnificus isolated from cockles and patients in Thailand.

Vibrio vulnificus can cause septicemia, wound infection and gastroenteritis. The most severe infections are related to consumption of raw or undercooked seafood. Virulence genes, biomarkers, antimicrobial resistance, and genetic relationships among V vulnificus isolated from clinical and environmental sources in Thailand have not hitherto been investigated. ViuB encoding vulnibactin siderophore was detected in 33% and 50% of clinical and environmental (cockle) V. vulnificus isolates, respectively, and capsular polysaccharide allele 1 in 67% and 75% of clinical and environmental isolates, respectively. Analysis of the 16 S rDNA gene revealed that type B was the most frequent in both clinical and environmental isolates (67%) whereas the non type-able (30%) was detected only in environmental isolates. The virulence-correlated gene (vcg) with both type C and E together was the most frequently found among the clinical (67%) and environmental (72%) isolates. Pulsed-field gel electrophoresis differentiated V vulnificus into 2 clusters; most cockle samples (83%) and all clinical isolates grouped into cluster II, indicating a possible clonal relationship between V. vulnificus isolated from patients and cockles. Only 20% of environmental isolates were resistant to ampicillin. These studies suggest that V vulnificus isolated from cockles has virulence genes similar to those in clinical isolates and thus may have the potential of causing disease.