Identification of Vibrio vulnificus by indirect immunofluorescence

A rapid, sensitive, and specific indirect immunofluorescence (IIF) procedure is described for identifying Vibrio vulnificus. Reference antisera were prepared by vaccinating rabbits with surface antigen preparations of V. vulnificus, and the antisera were examined for the ability to react with and serologically group 85 isolates of V. vulnificus grown in heart infusion broth, and to detect V. vulnificus in tissue specimens from mice experimentally infected with a virulent isolate of the bacterium. The antisera detected 100% of the V. vulnificus isolates examined and gave false-positive results in approximately 0.9% of 445 IIF tests performed with non-V. vulnificus clinical isolates. V. vulnificus also was detected in frozen tissue sections from infected mice; however, the most easily observed positive results were obtained by examining V. vulnificus from lesion specimens and blood cultured briefly in heart infusion broth. The bacteria in 2-hr-old cultures of local lesions fluoresced brilliantly and were easily detectable. The IIF procedure could be of value in rapidly diagnosing fulminating and potentially fatal human disease caused by V. vulnificus.