Detection of genes encoding cholera toxin (CT), zonula occludens toxin (ZOT), accessory cholera enterotoxin (ACE) and heat-stable enterotoxin (ST) in Vibrio mimicus clinical strains

A total of 51 clinical strains of Vibrio mimicus were searched for the presence of virulence-associated genes, like ctx, zot or ace genes which locate in "cholera virulence cassette," and the st gene by polymerase chain reaction. Moreover, the pathological potential of each clinical strain was also examined by rabbit ileal loop (RIL). Three strains showed to have the ctx gene, of which only one strain was zot gene-positive. Meanwhile, one other strain was zot+ but ctx-. All of these four strains were found to have the ace gene and to belong to serogroup O115. Nine strains showed to carry the st gene. However, none of these ST-gene-positive strains was indicated to contain the genes located in the "cholera virulence cassette." It is of interest to note that all of the RIL-positive and/or virulence gene-positive strains were restricted to three serogroups, O20, O41 and O115. These results suggest a significant association between O antigens and enterotoxic activities in V. mimicus clinical strains, and clearly demonstrate multifactorial virulence potentials of this human pathogen.