Category Archives: Vibrio parahaemolyticus

RASFF Alert – Vibrio parahaemolyticus – Frozen Raw Whole Shrimps


RASFF – Vibrio parahaemolyticus (ToxR+ Tdh+ /25g) in frozen raw whole shrimps from Ecuador, via Spain in France

USA – Vibrio Shigella E. coli Outbreak Linked to Raw Oysters in California

Food Poisoning Bulletin

A Vibrio Shigella E. coli and norovirus outbreak linked to raw oysters from Baja California Sur, Mexico has sickened at least 12 people in California, according to the California Department of Public Health (CDPH).

Those twelve patients reported illnesses in February, March, and April 2019 after consuming raw oysters that were sold by restaurants and retailers in Los Angeles, Orange, Santa Barbara, and San Diego counties. The raw oysters were sold throughout the state.

Lab testing was performed on isolates from eight cases. Officials identified Vibrio parahaemolyticus in three patients, Vibrio albensis in one, an unidentified species of Vibrio in one patient, Shigella flexneri serotype 1 in two patients, and norovirus. In addition, one of the people infected with Vibrio parahaemolyticus cases was co-infected with non-O157 Shiga toxin-producing E. coli bacteria.

Traceback evidence has shown that the oysters were harvested from Estero El Cardon. Authorities in Mexico have been notified about this outbreak and are investigating.

RASFF Alert – Vibrio parahaemolyticus – Frozen Shrimps


RASFF – Vibrio parahaemolyticus (present /25g) in frozen shrimps (Penaeus vannamei) from India in the Netherlands

Research – Enzymatic Inactivation of Pathogenic and Nonpathogenic Bacteria in Biofilms in Combination with Chlorine

Journal of Food Protection

This study investigated the effects of enzyme application on biofilms of bacterial isolates from a cafeteria kitchen and foodborne pathogens and the susceptibility of Salmonella biofilms to proteinase K combined with chlorine treatment. For four isolates from a cafeteria kitchen (Acinetobacter, Enterobacter, and Kocuria) and six strains of foodborne pathogens (Salmonella enterica, Staphylococcus aureus, and Vibrio parahaemolyticus), the inhibitory effect of enzymes on biofilm formation at 25°C for 24 h or the degradative efficacy of enzymes on 24-h mature biofilm at 37°C for 1 h in tryptic soy broth (TSB) was examined in a polystyrene microtiter plate. The effect of enzymes was also evaluated on a subset of these strains in 20 times diluted TSB (1/20 TSB) at 25°C. The working concentrations of five enzymes were 1 U/100 μL for α-amylase, amyloglucosidase, cellulase, and DNase and 1 milli-Anson unit/100 μL for proteinase K. In addition, 24-h mature SalmonellaTyphimurium biofilm on a stainless steel coupon was treated with proteinase K for 1 h at 25°C followed by 20 ppm of chlorine for 1 min at 25°C. The results showed that certain enzymes inhibited biofilm formation by the kitchen-originated bacteria; however, the enzymatic effect was diminished on the mature biofilms. Biofilm formation of V. parahaemolyticus was suppressed by all tested enzymes, whereas the mature biofilm was degraded by α-amylase, DNase I, and proteinase K. Proteinase K was effective in controlling Salmonella biofilms, whereas a strain-dependent variation was observed in S. aureusbiofilms. In 1/20 TSB, Enterobacter cancerogenus and Kocuria varians were more susceptible to certain enzymes during biofilm formation than those in TSB, whereas the enzymatic effect was much decreased on 24-h mature biofilms, regardless of nutrient conditions. Furthermore, synergistic inactivation of Salmonella Typhimurium in biofilms was observed in the combined treatment of proteinase K followed by chlorine. Live/Dead assays also revealed a decrease in density and loss of membrane integrity in Salmonella Typhimurium biofilms exposed to the combined treatment. Therefore, certain enzymes can control biofilms of isolates residing in a cafeteria kitchen and foodborne pathogens. This study demonstrates the potential of enzymes for the sanitation of food processing environments and of proteinase K combined with chlorine to control Salmonella biofilms on food contact surfaces.

RASFF Alerts – Vibrio cholerae and Vibrio parahaemolyticus – Frozen Shrimp


RASFF – Vibrio cholerae and Vibrio parahaemolyticus in frozen shrimp from Vietnam in Norway

Research – Vibrio spp. from Yesso scallop (Patinopecten yessoensis) demonstrating virulence properties and antimicrobial resistance

Wiley Online Library


We report the prevalence and characterization of Vibrio spp. isolated from marketed Yesso scallop (Patinopecten yessoensis) in Korea. A total of 30 isolates including, V. parahaemolyticus (n = 2), V. alginolyticus (n = 9), V. fluvialis (n = 7), V. diabolicus (n = 7), V. anguillarum (n = 4) and V. aestuarianus (n = 1) were isolated and identified. The phenotypic pathogenicity tests demonstrated that, 18 (60%), 21 (70%), 18 (60%), 7 (23%), 22 (73%), 21 (70%), 9 (30%), and 11 (33%) of the isolates were positive for DNase, protease, gelatinase, lipase, phospho‐lipase, amylase, slime production, and haemolysis, respectively. PCR assays revealed the prevalence of toxR, tlh, VAC, vfh, hupO, and VPI genes among the isolates with varying combinations. A close genetic affinity among V. alginolyticus and V. diabolicus strains was observed. Also the virulence genes specific to one Vibrio species were detected among other species as well. In addition, 29/30 (97%) isolates were multidrug resistant, while higher resistance rates were shown for ampicillin, colistin, vancomycin, and cephalothin. The results imply that the scallops in Korean markets harbor Vibrio spp., which are potentially virulent and multidrug resistant, thus their public health implications should not be underrated.

Practical applications

For many decades, vibrios are known for its importance in seafoodborne illnesses. Yesso scallop is the most popular and extensively cultured scallop variety in Korea. Therefore, we sought to assess the marketed fresh Yesso scallops for the prevalence and molecular characterization of Vibrio species. A total of 30 strains were isolated and identified by a series of biochemical tests, subsequent gyrB gene sequencing and phylogenetic analyses. Six Vibrio spp. were identified with V. alginolyticus as the most prevalent. Interestingly, V. alginolyticus was genetically similar to V. diabolicus. Besides, the virulence genes specific to V. alginolyticus and V. parahaemolyticus were observed in other species as well. It suggests that the detection of the species‐specific genes does not ensure the correct identification of pathogenic vibrios. Further, the occurrence of V. parahaemolyticus‐specific virulence genes in other Vibrio spp. potentially complicates the correct tracking of V. parahaemolyticus infections. In addition, 73% of these Vibrio spp. isolates showed multiple antibiotic resistance (MAR) indices higher than 0.2, which signifies their high risk of infection. Collectively, these results provide important evidence that not only the well‐known pathogenic vibrios like V. parahaemolyticus, but also other Vibrio spp. can act alike because of their similar characteristics.

Research – Long-Term Depuration of Crassostrea virginica Oysters at Different Salinities and Temperatures Changes Vibrio vulnificus Counts and Microbiological Profile

Journal of Food Protection

Previous short-duration depuration studies with the eastern oyster (Crassostrea virginica) demonstrated difficulty in achieving significant naturally incurred Vibrio vulnificus population count reductions. The present study used long-duration depuration (14 days) at controlled temperatures (10 or 22°C) and salinities (12, 16, or 20 mg/g). All depuration temperature–salinity combinations significantly reduced V. vulnificus counts, with greatest reductions seen in 12 mg/g, 10°C seawater (2.7-log CFU/g reduction) and in 20 mg/g, 22°C seawater (2.8-log reduction). Mesophilic vibrios dominated the overall microflora of freshly harvested oysters, whereas refrigerated storage selected for psychrotrophic bacteria (Pseudomonas spp., Aeromonas spp., Shewanella spp., Psychrobacter spp.) as well as did depuration at 10°C (Pseudoalteromonas spp., Shewanella spp., Vibrio spp.). Depuration at 22°C retained dominance of mesophilic vibrios, including pathogenic species, followed by Shewanella spp., Pseudoalteromonas spp., and Photobacterium spp. Although aerobic plate counts were lower in 22°C depurated oysters (5.0 log versus 6.0 log) compared with 10°C, depuration at 10°C offered greater V. vulnificus population reductions than depuration at 22°C. This advantage was only seen at 12 mg/g salinity, with no impact at 16 and 20 mg/g salinities. No depuration treatment reduced V. vulnificus counts to nondetectable levels. Use of prolonged depuration may be a helpful intervention to control V. vulnificus populations in oysters.