Seafood-Associated Outbreak of ctx-Negative Vibrio mimicus Causing Cholera-Like Illness, Florida, USA

Abstract

Vibrio mimicus caused a seafood-associated outbreak in Florida, USA, in which 4 of 6 case-patients were hospitalized; 1 required intensive care for severe diarrhea. Strains were ctx- negative but carried genes for other virulence determinants (hemolysin, proteases, and types I–IV and VI secretion systems). Cholera toxin–negative bacterial strains can cause cholera-like disease.

Vibrio mimicus Lineage Carrying Cholera Toxin and Vibrio Pathogenicity Island, United States and China

“…We highlight the presence of the heat-stable enterotoxin gene (NAG-ST), identified throughout the phylogeny, and gene clusters related to exopolysaccharide production ( vps ) and the type III secretion system (T3SS) ( vop , vsc , and vcr ). We identified T3SS only in genomes that did not carry CTX, TCP, or both, including those from the 2019 outbreak in Florida ( 5 ), but 2 closely related genomes (1 of which was identified in the United States) co-carried the T3SS and NAG-ST genes. Because T3SS is a syringe-like protein secretion apparatus, the co-occurrence of this system with a diarrhea-associated toxin could increase the pathogenicity of these strains.…”

“…In 2010, in the United States, a cluster of severe diarrheal diseases was caused by V. mimicus strains carrying CTX ( 4 ). In 2019, V. mimicus bacteria caused a seafood-associated outbreak in Florida (USA), in which the patients experienced severe diarrhea, although the strains were CTX-negative ( 5 ). However, the virulome of most genomes analyzed (n = 33) was not explored, leaving a gap regarding the association of the strains or lineages with virulence factors.…”

“…Our findings show that V. mimicus strains are spread throughout the world and that some of them carry a virulome comparable to that of V. cholerae bacteria. The virulome of environmental and clinical strains is apparently not heterogeneous ( 5 ), even with the analysis of the new environmental genomes. However, those findings may represent just the tip of the iceberg, given the bias regarding the locality of available genomes.…”