Abstract

Fifty-seven pandemic Vibrio parahaemolyticus isolates (tdh positive, trh negative GS-PCR positive) obtained from diarrheal patients at Hat Yai Hospital, Songkhla, Thailand during 2001-2016 were examined for their antibiogram profiles and virulence characteristics. Resistance to ampicillin, ciprofloxacin and norfloxacin was present in 100%, 12% and 2% of the isolates, respectively, with over half of the isolates showing intermediate resistance to the two fluoroquinolones. Virulence-associated genes encoding type III secretion systems (T3SS1 and T3SS2) and type VI secretion systems (T6SS1 and T6SS2) were widely distributed among the isolates. All isolates were able to produce similar levels of thermostable direct hemolysin. Eighty-nine percent and 44% of the isolates exhibited swarming and twitching motility, respectively. Sixty-eight percent of the isolates were able to use 50 µM hemoglobin as the only iron source and 81% in the presence of 155 µM hemoglobin. This study highlights the antimicrobial resistance and multiple virulence characteristics of clinical V. parahaemolyticus isolates, information that will be useful in clinical and epidemiological investigations of this pathogenic organism.