Seasonal and geographical differences in total and pathogenic vibrio parahaemolyticus and vibrio vulninficus levels in seawater and oysters from the Delaware and Chesapeake Bays using several methods

Authors: PARVEEN, SALINA - University Of Maryland Eastern Shore (UMES); JACOBS, JOHN - National Oceanic & Atmospheric Administration (NOAA); OZBAY, GULNIHAL - Delaware State University; CHINTAPENTA, LATHADEVI - Delaware State University; ALMUHAIDEB, ESAM - University Of Maryland Eastern Shore (UMES); MEREDITH, JOAN - University Of Maryland Eastern Shore (UMES); OSSAI, SYLVIA - University Of Maryland Eastern Shore (UMES); ABBOTT, AMANDA - University Of Maryland Eastern Shore (UMES); GRANT, ARQUETTE - University Of Maryland Eastern Shore (UMES); BROHAWN, KATHY - Maryland Department Of Environment; CHIGBU, PAULINUS - University Of Maryland Eastern Shore (UMES); Richards, Gary

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2020
Publication Date: 11/10/2020
Citation: Parveen, S., Jacobs, J., Ozbay, G., Chintapenta, L., Almuhaideb, E., Meredith, J., Ossai, S., Abbott, A., Grant, A., Brohawn, K., Chigbu, P., Richards, G.P. 2020. Seasonal and geographical differences in total and pathogenic vibrio parahaemolyticus and vibrio vulninficus levels in seawater and oysters from the Delaware and Chesapeake Bays using several methods. Applied and Environmental Microbiology. 86(23). https://doi.org/10.1128/AEM.01581-20.
DOI: https://doi.org/10.1128/AEM.01581-20

Interpretive Summary: Vibrio parahaemolyticus and Vibrio vulnificus are significant causes of shellfish-associated illnesses and deaths among shellfish consumers. Current regulatory assays for vibrios are complex, time-consuming, labor intensive, and relatively expensive. In this study, the rapid, simple and inexpensive Colony Overlay Procedure for Peptidases (COPP) assay was identified as a possible alternative to the standard Most Probable Number-PCR assay for shellfish monitoring. Abundances and frequencies of occurrence of total and pathogenic strains of V. parahaemolyticus and V. vulnificus were also determined and showed unexpected differences between Delaware Bay and Chesapeake Bay oysters and seawater. These studies suggest that higher salinity and turbidity in Delaware Bay seawater may have been responsible for higher levels of V. parahaemolyticus in the Delaware Bay than in the Chesapeake Bay.

Technical Abstract: Oyster and seawater samples were collected from five sites in the Chesapeake Bay, MD, and three sites in the Delaware Bay, DE, from May-October 2016 and 2017. Abundances and detection frequencies for total and pathogenic Vibrio parahaemolyticus and Vibrio vulnificus were compared using the standard Most Probable Number-PCR (MPN-PCR) assay and a direct plating (DP) method on CHROMagar Vibrio for total (tlh positive) and pathogenic (tdh and trh positive) V. parahaemolyticus genes, and total (vvhA) and pathogenic (vcgC) genes for V. vulnificus. The Colony Overlay Procedure for Peptidases (COPP) assay was evaluated for total Vibrionaceae. DP had high false negative rates (14-77%) for most PCR targets and was deemed unsatisfactory. Logistic regression models of the COPP assay showed high concordances with MPN-PCR for tdh and trh positive V. parahaemolyticus and vvhA positive V. vulnificus in oysters (85.7-90.9%) and seawater (81.1-92.7%) when seawater temperature and salinity were factored into the model, suggesting that the COPP assay could potentially serve as a more rapid method to detect vibrios in oysters and seawater. Differences in total and pathogenic Vibrio abundances between state sampling sites over different collection years were contrasted for oysters and seawater by MPN-PCR. Abundances of tdh and trh positive V. parahaemolyticus were approximately 8-fold higher in Delaware than in Maryland oysters, whereas abundances of vcgC positive V. vulnificus were nearly identical. For Delaware oysters, 93.5% were both tdh and trh positive compared to only 19.2% in Maryland. These results indicate that pathogenic V. parahaemolyticus was more prevalent in the Delaware Bay compared to the Chesapeake Bay.