Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Dec 3;15(12):e0242229.
doi: 10.1371/journal.pone.0242229. eCollection 2020.

Assessment of Vibrio parahaemolyticus levels in oysters (Crassostrea virginica) and seawater in Delaware Bay in relation to environmental conditions and the prevalence of molecular markers to identify pathogenic Vibrio parahaemolyticus strains

Esam Almuhaideb  1 , Lathadevi K Chintapenta  2 , Amanda Abbott  2 , Salina Parveen  3 , Gulnihal Ozbay  2
Affiliations

Assessment of Vibrio parahaemolyticus levels in oysters (Crassostrea virginica) and seawater in Delaware Bay in relation to environmental conditions and the prevalence of molecular markers to identify pathogenic Vibrio parahaemolyticus strains

Esam Almuhaideb et al. PLoS One. .

Abstract

This study identified Vibrio parahaemolyticus in oyster and seawater samples collected from Delaware Bay from June through October of 2016. Environmental parameters including water temperature, salinity, dissolved oxygen, pH, and chlorophyll a were measured per sampling event. Oysters homogenate and seawater samples were 10-fold serially diluted and directly plated on CHROMagarᵀᴹ Vibrio medium. Presumptive V. parahaemolyticus colonies were counted and at least 20% of these colonies were selected for molecular chracterization. V. parahaemolyticus isolates (n = 165) were screened for the presence of the species-specific thermolabile hemolysin (tlh) gene, the pathogenic thermostable direct hemolysin (tdh)/ thermostable related hemolysin (trh) genes, the regulatory transmembrane DNA-binding gene (toxR), and V. parahaemolyticus metalloprotease (vpm) gene using a conventional PCR. The highest mean levels of the presumptive V. parahaemolyticus were 9.63×103 CFU/g and 1.85×103 CFU/mL in the oyster and seawater samples, respectively, during the month of July. V. parahaemolyticus levels in oyster and seawater samples were significantly positively correlated with water temperature. Of the 165 isolates, 137 (83%), 110 (66.7%), and 108 (65%) were tlh+, vpm+, and toxR+, respectively. Among the V. parahaemolyticus (tlh+) isolates, 7 (5.1%) and 15 (10.9%) were tdh+ and trh+, respectively, and 24 (17.5%), only oyster isolates, were positive for both genes. Potential pathogenic strains that possessed tdh and/or trh were notably higher in oyster (39%) than seawater (15.6%) isolates. The occurrence of total V. parahaemolyticus (tlh+) was not necessarily proportional to the potential pathogenic V. parahaemolyticus. Co-occurrence of the five genetic markers were observed only among oyster isolates. The co-occurrence of the gene markers showed a relatedness potential of tdh occurrence with vpm. We believe exploring the role of V. parahaemolyticus metalloprotease and whether it is involved in the toxic activity of the thermostable direct hemolysin (TDH) protein can be of significance. The outcomes of this study will provide some foundation for future studies regarding pathogenic Vibrio dynamics in relation to environmental quality.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Study locations in Delaware Bay.
Fig 2
Fig 2. Average Vibrio parahaemolyticus levels (log10 CFU/g) in oyster samples in relation to collection time, study sites, and water parameters (temperature and salinity).
Bowers Beach (BB)—Lewes, Broadkill (LW)—Slaughter Beach (SL). * (Not detectable).
Fig 3
Fig 3. Average Vibrio parahaemolyticus levels (log10 CFU/mL) in seawater samples in relation to collection time, study sites, and water parameters (temperature and salinity).
Bowers Beach (BB)—Lewes, Broadkill (LW)—Slaughter Beach (SL). * (Not detectable).
Fig 4
Fig 4. Percent and number of isolates with detected tdh, trh, toxR, vpm and tlh genes in oysters and seawater.
Fig 5
Fig 5. Number of isolates with coexisting genes among total confirmed V. parahaemolyticus isolates.
Fig 6
Fig 6. Co-existence of genes among confirmed V. parahaemolyticus isolates from oysters.
Fig 7
Fig 7. Co-existence of genes among confirmed V. parahaemolyticus isolates from seawater.
See this image and copyright information in PMC

References

    1. Lee CT, Chen IT, Yang YT, Ko TP, Huang YT, Huang JY, et al. The opportunistic marine pathogen Vibrio parahaemolyticus becomes virulent by acquiring a plasmid that expresses a deadly toxin. Proc Natl Acad Sci U S A. 2015;112(34):10798–803. 10.1073/pnas.1503129112 - DOI - PMC - PubMed
    1. Luan X, Chen J, Zhang XH, Li Y, Hu G. Expression and characterization of a metalloprotease from a Vibrio parahaemolyticus isolate. Can J Microbiol. 2007;53(10):1168–73. 10.1139/W07-085 - DOI - PubMed
    1. Morris JG Jr, Black RE. Cholera and other vibrioses in the United States. N Engl J Med. 1985;312(6):343–50. 10.1056/NEJM198502073120604 - DOI - PubMed
    1. Fujino T, Okuno Y, Nakada D, Aoyama A, Fukai K, Mukai T, et al. On the bacteriological examination of shirasu-food poisoning. Medical Journal of Osaka University. 1953;4(2/3):299–304.
    1. Daniels NA, MacKinnon L, Bishop R, Altekruse S, Ray B, Hammond RM, et al. Vibrio parahaemolyticus infections in the United States, 1973–1998. The Journal of infectious diseases. 2000;181(5):1661–6. 10.1086/315459 - DOI - PubMed

Publication types

Substances