Serodiversity, Pandemic O3:K6 Clone, Molecular Typing, and Antibiotic Susceptibility of Foodborne and ClinicalVibrio parahaemolyticusIsolates in Jiangsu, China

Abstract

Vibrio parahaemolyticus is a major foodborne pathogen in China, Japan, and other Asian countries. In this study, we collected 437 strains of V. parahaemolyticus and investigated their serotypes, distribution of virulence genes, and presence of pandemic O3:K6 clone strains. A total of 327 strains were isolated from food and 110 strains were isolated from active surveillance hospitals or food outbreaks during 2005 to 2008. Presence of the tdh and trh genes is the key characteristic of virulent strains. Positive for both the tdh gene and group-specific polymerase chain reaction is the key characteristic of pandemic strains. A total of 9 O serogroups and 62 serovars were identified in all strains. Nine O serogroups and 56 serovars existed in 327 foodborne strains, and 6 O serogroups and 20 serovars existed in 110 clinical strains. Among the 327 food isolates, 6 isolates belonged to the pandemic clone with the orf8 gene (1 isolate was O1:KUT (untyped) and 5 isolates were O3:K6) and 4 isolates carried the trh gene (2 isolates belonged to O1:KUT and 2 isolates belonged to O5:KUT and O5:K17). Seventy-nine percent of the clinical isolates were pandemic strains, 9.4% of which lacked the orf8 gene. O3:K6 was the main serovar of the pandemic strains accounting for 83.5% of the clinical pandemic strains. Pandemic clonal serovars included O3:K6, O1:KUT, O1:K25, O1:K26, and O4:K68, and the newly emerging serovars O1:K36, O3:K25, and O3:K68 identified in the current study. O3:K6 was the dominant serovar in pandemic strains. All pandemic isolates had identical arbitrarily primed polymerase chain reaction fragment patterns, but did not share similar antibiotic sensitivity patterns. These results suggest that high serodiversity of V. parahaemolyticus was present in foodborne strains. Pathogenic isolates, especially pandemic isolates, were present in high-priced iced seafood and became the potential risk factor in food.

Association of Pandemic Vibrio parahaemolyticus O3:K6 Present in the Coastal Environment of Northwest Mexico with Cases of Recurrent Diarrhea between 2004 and 2010

“…Serotyping analysis demonstrates that there were fewer serogroups and serovars in clinical isolates than in environmental isolates, clearly demonstrating that clinical isolates belong to a specific group of strains, in agreement with other studies (14). Whether these strains will contain other or unknown virulence determinants remains to be investigated.…”

“…Previous studies have shown that isolates belonging to the new clone O3:K6 (tdh positive, toxRS new positive) are associated with outbreaks of human gastroenteritis (36,45,46); however, as in our study, these strains are rarely isolated from environmental samples (14,19,53). In the current contribution, the few environmental isolates belonging to the pandemic serotype were O3:K6 (in seawater, shrimp, and sediment), O3:KUT (in seawater), and O10:KUT (in sediment).…”

“…Therefore, the presence of these genes is routinely used to determine the pathogenicity of V. parahaemolyticus strains (30). In molecular epidemiological studies, it has been shown that clinical isolates possess the tdh and/or trh gene in up to 90% of clinical strains (serotype O3:K6 strain has increasing prominence) (14,22,45), whereas their presence in environmental isolates is rare (14,17,26,40,44,52,57). Data on the current study are in accordance with these previous observations, as 93% of all clinical strains carried the tdh and/or the trh gene (80.5% were in the pandemic group and 12.9% were in the pathogenic group).…”

Environmental parameters influence on the dynamics of total and pathogenic Vibrio parahaemolyticus densities in Crassostrea virginica harvested from Mexico’s Gulf coast

“…The orf8 gene is believed to encode an adherence protein that increases the ability of V. parahaemolyticus to adhere to host intestinal cells or to the surfaces of marine plankton (Nasu et al, 2000). The occurrence of orf8 genes in foodborne strains has been reported and it has been considered as an additional virulence factor for V. parahaemolyticus (Nasu et al, 2000;Iida et al, 2001;Chao et al, 2009). Therefore, as only a small proportion of the environmental strains are virulent, it would be necessary to detect pathogenic tdh/trh and orf8 strains in the oysters to determine seafood safety.…”

Production and characterization of a monoclonal antibody against recombinant thermolabile hemolysin and its application to screen for Vibrio parahaemolyticus contamination in raw seafood

“…At present, V. parahaemolyticus often causes health problems around the world in locations such as Japan, Asia, and the United States (Chao et al, 2009;Su & Liu, 2007;Yeung & Boor, 2004).…”