Etiological analysis of a small outbreak of gastroenteritis with Vibrio parahaemolyticus infection

Abstract

ObjectiveTo investigate the etiology of a small outbreak of gastroenteritis caused by Vibrio parahaemolyticus in Guangzhou, 2017.MethodsSerotype identification, antimicrobial susceptibility test, polymerase chain reaction (PCR) test of virulence genes (tdh, trh, tlh), toxRS/new gene, orf8 gene, pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were analyzed.ResultsThe serotype O8∶K21 was identified. All isolates were sensitive to ceftriaxone, ciprofloxacin, chloramphenicol, cotrimoxazole, sulfonamide complex, amikacin, nalidixic acid, streptomycin, tetracycline and gentamicin, and resistant to ampicillin and trimethoprim. The PCR detection of virulence gene showed that all the strains were positive for tdh (thermostable direct hemolysin) and tlh (themolabile hemolysin), but negative for trh (tdh-related hemolysin), and carried toxRS/new and orf8 genes. According to PFGE cluster analysis, they were considered to be a highly related strains. According to MLST analysis, the results were all ST479 type.ConclusionThe reason for the small outbreak of gastroenteritis was due to Vibrio parahaemolyticus O8∶K21, which shared common genetic characteristics. It harbored the tdh gene which was the key characteristic of pandemic strains, and additional surveillance should be conducted to facilitate control of the transmission of this pathogen.

Keywords

• vibrio parahaemolyticus
• o8∶k21
• virulence genes
• pulsed field gel electrophoresis
• multilocus sequence typing