Antibiotic Resistance in the Shellfish Pathogen Vibrio parahaemolyticus isolated from the Coastal Water and Sediment of Georgia and South Carolina, USA

Craig Baker-Austin¹, J. V. McArthur¹, R. Cary Tuckfield², Michael Najarro³,
Angela H. Lindell¹, Jan Gooch⁴, and Ramunas Stepanauskas⁵

¹Savannah River Ecology Laboratory, Drawer E, Aiken, South Carolina 29802, USA
²Savannah River National Laboratory, Building 773-42A, Aiken, South Carolina 29808, USA
³University of California, Santa Cruz, Santa Cruz, California 95064, USA
⁴National Oceanographic and Atmospheric Administration, Charleston, South Carolina 19405, USA
⁵Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine 04575, USA

Abstract: Vibrio parahaemolyticus is a gram-negative pathogen commonly encountered in estuarine and marine environments, and a common cause of seafood-related gastrointestinal infections. We isolated 350 V. parahaemolyticus strains from water and sediment at three locations along the Atlantic coast of Georgia and South Carolina during various seasons. These isolates were tested for susceptibility to 24 antibiotics. Isolate virulence was determined through PCR of tdh and trh genes. The breadth of resistance to antibiotics was unexpectedly high, with 24% isolates demonstrating resistance to 10 or more agents. A significant fraction of isolates were resistant to diverse ß-lactams, aminoglycosides, and other classes of antibiotics. Fifteen of the 350 strains possessed virulence genes, with no apparent correlation between virulence and site, sample type, or season of isolation. Antibiotic resistance was slightly reduced among the virulent strains. This study represents one of the largest surveys to date of the virulence and antibiotic resistance in environmental V. parahaemolyticus strains. The observed antibiotic susceptibility patterns suggest that current guidelines for the antibiotic treatment of non-cholerae Vibrio should be reevaluated and extended.