P1-70 Characterization of Vibrio parahaemolyticus and Vibrio vulnificus Recovered from Oysters during the Salinity Relaying Process

Monday, July 10, 2017
Exhibit Hall (Tampa Convention Center)
Sara Elmahdi , University of Maryland Eastern Shore , Princess Anne , MD
Sylvia Ossai , University of Maryland Eastern Shore , Princess Anne , MD
Ligia DaSilva , University of Maryland Eastern Shore , Princess Anne , MD
John Jacobs , NOAA , Oxford , MD
Michael Jahncke , Virginia Polytechnic Institute and State University , Blacksburg , VA
Salina Parveen , University of Maryland Eastern Shore , Princess Anne , MD
Introduction:  Vibrio parahaemolyticus (Vp) and Vibrio vulnificus (Vv) are naturally occurring estuarine bacteria and are the leading causes of seafood-associated infections and mortality in the United States of America. Though multiple-antibiotic resistant Vp and Vv have been reported due to misuse of antibiotics to control infections in aquaculture production, resistance patterns in vibrios are not as well documented as other foodborne bacterial pathogens. Moreover, information is limited regarding the influence of post-harvest treatment strategies on the phenotypic and genotypic characteristics of these pathogens.

Purpose: The purpose of this study was to evaluate the antimicrobial susceptibility, as well as the pathogenicity and genetic profiles of Vp and Vv recovered from oysters during the salinity relaying process.

Methods:  Vv (n=296) and Vp (n=94) isolates were recovered from oysters, before and during the 21 day relaying study to detect virulence genes (tdh, trh, vcgC), using multiplex q-PCR. Antibiotic susceptibility to 20 different antibiotics was investigated using micro broth dilution and pulsed-field gel electrophoresis (PFGE) was used to study the genetic profiles of these pathogens.

Results: Twenty percent of Vv isolates were vcgC+, while 1 and 2% of Vp were tdh+ and trh+, respectively. More than 77% of Vv and 25% of Vp isolates were resistant to at least one antimicrobial. Forty eight percent of Vv and 8% of Vp isolates were resistant to two or more antimicrobials. All isolates demonstrated a high genetic diversity, even among those isolated from the same site and having a similar antimicrobial susceptibility profile. The relaying process had no significant effect on the antimicrobial susceptibility and PFGE profiles of Vv and Vp were observed (P=0.23).

Significance: This study provides a valuable information for risk management decisions, for both the oyster industry and regulatory agencies, as multiple antibiotic resistance represents a major concern in fish and shellfish farming and in human health.