Eating oysters without risk of vibriosis: Application of a bacteriophage against Vibrio parahaemolyticus in oysters

• We designed artificial Vibrio parahaemolyticus contamination conditions mostly encountered during oyster processing.
• The growth of the bacterial strain was reduced when oysters were treated with bath immersion with the phage.
• Bacterial growth was inhibited when the phage was surface-applied on the flesh of oysters.

Vibrio parahaemolyticus is a major cause of foodborne illness and related with the consumption of raw contaminated seafood, especially oysters. To evaluate the effectiveness of various applications of a bacteriophage (phage), pVp-1, against a multiple-antibiotic-resistant V. parahaemolyticus pandemic strain (CRS 09-17), we designed artificial contamination models that are most likely to be encountered during oyster processing. When live oysters were treated with bath immersion with pVp-1 after CRS 09-17 challenge, the growth of bacterial strain was significantly reduced. After 72 h of phage application with bath immersion, bacterial growth reduction was observed to be 8.9 × 106 CFU/ml (control group) to 1.4 × 10 CFU/ml (treatment group). When pVp-1 was surface-applied on the flesh of oysters after CRS 09-17 inoculation, bacterial growth was properly inhibited. After 12 h of phage application on the surface of oysters, bacterial growth inhibition was revealed to be 1.44 × 106 CFU/ml (control group) to 1.94 CFU/ml (treatment group). This is the first report, to the best of our knowledge, of oyster surface-application of a phage against a multiple-antibiotic-resistant V. parahaemolyticus pandemic strain, and our successful phage application to various situations emphasizes the potential use of the phage to avoid V. parahaemolyticus infection from aquaculture to consumption.