Prevalence and Population Structure of Vibrio vulnificus on Fishes from the Northern Gulf of Mexico

Abstract

The prevalence of Vibrio vulnificus on the external surfaces of fish from the northern Gulf of Mexico was determined in this study. A collection of 242 fish comprising 28 species was analyzed during the course of 12 sampling trips over a 16-month period. The prevalence of V. vulnificus was 37% but increased up to 69% in summer. A positive correlation was found between the percentages of V. vulnificus-positive fish and water temperatures, while salinity and V. vulnificus-positive fish prevalence were inversely correlated. A general lineal model (percent V. vulnificus-positive fish ‫؍‬ 0.5930 ؊ 0.02818 ؋ salinity ؉ 0.01406 ؋ water temperature) was applied to best fit the data. Analysis of the population structure was carried out using 244 isolates recovered from fish. Ascription to 16S rRNA gene types indicated that 157 isolates were type A (62%), 72 (29%) were type B, and 22 (9%) were type AB. The percentage of type B isolates, considered to have greater virulence potential, was higher than that previously reported in oyster samples from the northern Gulf of Mexico. Amplified fragment length polymorphism (AFLP) was used to resolve the genetic diversity within the species. One hundred twenty-one unique AFLP profiles were found among all analyzed isolates, resulting in a calculated Simpson's index of diversity of 0.991. AFLP profiles were not grouped on the basis of collection date, fish species, temperature, or salinity, but isolates were clustered into two main groups that correlated precisely with 16S rRNA gene type. The population of V. vulnificus associated with fishes from the northern Gulf of Mexico is heterogeneous and includes strains of great virulence potential.

Season-Specific Occurrence of Potentially Pathogenic Vibrio spp. on the Southern Coast of South Korea

“…When winter is over, vibrios released from the sediment attach to zooplankton and reproduce rapidly as the temperature increases (28). Other factors, such as V. vulnificus-positive fish, were found to be inversely correlated to salinity (Pearson's correlation coefficient r ϭ Ϫ0.91077, P Ͻ 0.0001) and positively correlated to temperature (Pearson's correlation coefficient r ϭ 0.62481, P Ͻ 0.0298) in the northern Gulf of Mexico (24). V. parahaemolyticus was frequently reported from tropical and subtropical oysters (99% positive in Brazil, 94% in India, 100% in the United States, and 71% in Taiwan) (10).…”

“…The pathogenicity of V. cholerae depends on a combination of properties, including the presence of cholera toxin (CT), encoded by ctxA, and the colonization and adhesion factor encoded by tcpA (22,23). Studies have shown seasonal patterns for this species, with increased occurrence and incidence of wound infections at warmer temperatures (24).…”

The Biology of Vibrio vulnificus

“…vulnificus and V. vulnificus infections have been reported throughout Europe, Scandinavia, South America, the Far East, South Pacific, as well as on all coasts of the United States (15). Along with oysters and other molluscan bivalves and estuarine/coastal waters, V. vulnificus has been reported in fish (82,83,84), sediments (85,86), and plankton (73). The presence of this pathogen appears to be spreading to areas where it was not previously reported, and this is likely due to global warming (see below).…”

The Fish Pathogen Vibrio vulnificus Biotype 2: Epidemiology, Phylogeny, and Virulence Factors Involved in Warm-Water Vibriosis

“…vulnificus biotype 2 was considered an obligate eel pathogen whose main reservoir was the farmed eel (28). This idea was apparently confirmed by its successful isolation from diseased eels, but not from asymptomatic carriers, tank water (even during the outbreaks), wild eels or other environmental sources (waters, oysters) (1,2,48,49,50,51,52). To demonstrate that water could be a natural reservoir for this biotype, survival experiments in artificial and natural water microcosms over short and long terms (months or years) were performed (53,54).…”