scholarly journals Predictive Models for the Effect of Storage Temperature on Vibrio parahaemolyticus Viability and Counts of Total Viable Bacteria in Pacific Oysters (Crassostrea gigas)

2011 ◽  
Vol 77 (24) ◽  
pp. 8687-8695 ◽  
Author(s):  
Judith Fernandez-Piquer ◽  
John P. Bowman ◽  
Tom Ross ◽  
Mark L. Tamplin
Keyword(s):  
Predictive Models ◽  
Crassostrea Gigas ◽  
Vibrio Parahaemolyticus ◽  
Natural Populations ◽  
Parameter Estimates ◽  
Square Root ◽  
Probable Number ◽  
Direct Plating ◽  
Content Type ◽  
Pacific Oysters

ABSTRACTVibrio parahaemolyticusis an indigenous bacterium of marine environments. It accumulates in oysters and may reach levels that cause human illness when postharvest temperatures are not properly controlled and oysters are consumed raw or undercooked. Predictive models were produced by injecting Pacific oysters (Crassostrea gigas) with a cocktail ofV. parahaemolyticusstrains, measuring viability rates at storage temperatures from 3.6 to 30.4°C, and fitting the data to a model to obtain parameter estimates. The models were evaluated with Pacific and Sydney Rock oysters (Saccostrea glomerata) containing natural populations ofV. parahaemolyticus. V. parahaemolyticusviability was measured by direct plating samples on thiosulfate-citrate-bile salts-sucrose (TCBS) agar for injected oysters and by most probable number (MPN)-PCR for oysters containing natural populations. In parallel, total viable bacterial counts (TVC) were measured by direct plating on marine agar. Growth/inactivation rates forV. parahaemolyticuswere −0.006, −0.004, −0.005, −0.003, 0.030, 0.075, 0.095, and 0.282 log10CFU/h at 3.6, 6.2, 9.6, 12.6, 18.4, 20.0, 25.7, and 30.4°C, respectively. The growth rates for TVC were 0.015, 0.023, 0.016, 0.048, 0.055, 0.071, 0.133, and 0.135 log10CFU/h at 3.6, 6.2, 9.3, 14.9, 18.4, 20.0, 25.7, and 30.4°C, respectively. Square root and Arrhenius-type secondary models were generated forV. parahaemolyticusgrowth and inactivation kinetic data, respectively. A square root model was produced for TVC growth. Evaluation studies showed that predictive growth forV. parahaemolyticusand TVC were “fail safe.” The models can assist oyster companies and regulators in implementing management strategies to minimizeV. parahaemolyticusrisk and enhancing product quality in supply chains.

Effects of Flash Freezing, Followed by Frozen Storage, on Reducing Vibrio parahaemolyticus in Pacific Raw Oysters (Crassostrea gigas)

2009 ◽  
Vol 72 (1) ◽  
pp. 174-177 ◽  
Author(s):  
CHENGCHU LIU ◽  
JIANZHANG LU ◽  
YI-CHENG SU
Keyword(s):  
Crassostrea Gigas ◽  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Frozen Storage ◽  
Most Probable Number ◽  
Freezing Process ◽  
Probable Number ◽  
Pacific Oysters ◽  
Subsequent Storage ◽  
Shellfish Sanitation

This study investigated the effects of flash freezing, followed by frozen storage, on reducing Vibrio parahaemolyticus in Pacific raw oysters. Raw Pacific oysters were inoculated with a five-strain cocktail of V. parahaemolyticus at a total level of approximately 3.5 × 105 most probable number (MPN) per gram. Inoculated oysters were subjected to an ultralow flash-freezing process (−95.5°C for 12 min) and stored at −10, −20, and −30°C for 6 months. Populations of V. parahaemolyticus in the oysters declined slightly by 0.22 log MPN/g after the freezing process. Subsequent storage of frozen oysters at −10, −20, and −30°C resulted in considerable reductions of V. parahaemolyticus in the oysters. Storing oysters at −10°C was more effective in inactivating V. parahaemolyticus than was storage at −20 or −30°C. Populations of V. parahaemolyticus in the oysters declined by 2.45, 1.71, and 1.45 log MPN/g after 1 month of storage at −10, −20, and −30°C, respectively, and continued to decline during the storage. The levels of V. parahaemolyticus in oysters were reduced by 4.55, 4.13, and 2.53 log MPN/g after 6 months of storage at −10, −20, and −30°C, respectively. Three process validations, each separated by 1 week and conducted according to the National Shellfish Sanitation Program's postharvest processing validation–verification interim guidance for Vibrio vulnificus and Vibrio parahaemolyticus, confirmed that a process of flash freezing, followed by storage at −21 ± 2°C for 5 months, was capable of achieving greater than 3.52-log (MPN/g) reductions of V. parahaemolyticus in half-shell Pacific oysters.

Refrigerated Seawater Depuration for Reducing Vibrio parahaemolyticus Contamination in Pacific Oyster (Crassostrea gigas)

2010 ◽  
Vol 73 (6) ◽  
pp. 1111-1115 ◽  
Author(s):  
YI-CHENG SU ◽  
QIANRU YANG ◽  
CLAUDIA HÄSE
Keyword(s):  
Crassostrea Gigas ◽  
Vibrio Parahaemolyticus ◽  
Pacific Oyster ◽  
Most Probable Number ◽  
Probable Number ◽  
Log Reduction ◽  
Pacific Oysters ◽  
The Pacific ◽  
Postharvest Treatment ◽  
Depuration Process

The efficacy of refrigerated-seawater depuration for reducing Vibrio parahaemolyticus levels in Pacific oyster (Crassostrea gigas) was investigated. Raw Pacific oysters were inoculated with a mixed culture of five clinical strains of V. parahaemolyticus (105 to 106 most probable number [MPN] per g) and depurated with refrigerated seawater (5°C) in a laboratory-scale recirculation system equipped with a 15-W gamma UV sterilizer. Depuration with refrigerated seawater for 96 h reduced V. parahaemolyticus populations by >3.0 log MPN/g in oysters harvested in the winter. However, 144 h of depuration at 5°C was required to achieve a 3-log reduction in oysters harvested in the summer. Depuration with refrigerated seawater at 5°C for up to 144 h caused no significant fatality in the Pacific oyster and could be applied as a postharvest treatment to reduce V. parahaemolyticus contamination in Pacific oysters. Further studies are needed to validate the efficacy of the depuration process for reducing naturally accumulated V. parahaemolyticus in oysters.

scholarly journals Long-Term Study of Vibrio parahaemolyticus Prevalence and Distribution in New Zealand Shellfish

2015 ◽  
Vol 81 (7) ◽  
pp. 2320-2327 ◽  
Author(s):  
C. D. Cruz ◽  
D. Hedderley ◽  
G. C. Fletcher
Keyword(s):  
New Zealand ◽  
Vibrio Parahaemolyticus ◽  
Most Probable Number ◽  
Pcr Analysis ◽  
Potential Hazard ◽  
Probable Number ◽  
Content Type ◽  
The North ◽  
Long Term Study ◽  
Food Borne

ABSTRACTThe food-borne pathogenVibrio parahaemolyticushas been reported as being present in New Zealand (NZ) seawaters, but there have been no reported outbreaks of food-borne infection from commercially grown NZ seafood. Our study determined the current incidence ofV. parahaemolyticusin NZ oysters and Greenshell mussels and the prevalence ofV. parahaemolyticustdhandtrhstrains. Pacific (235) and dredge (21) oyster samples and mussel samples (55) were obtained from commercial shellfish-growing areas between December 2009 and June 2012. TotalV. parahaemolyticusnumbers and the presence of pathogenic genestdhandtrhwere determined using the FDA most-probable-number (MPN) method and confirmed using PCR analysis. In samples from the North Island of NZ,V. parahaemolyticuswas detected in 81% of Pacific oysters and 34% of mussel samples, while the numbers ofV. parahaemolyticustdhandtrhstrains were low, with just 3/215 Pacific oyster samples carrying thetdhgene.V. parahaemolyticusorganisms carryingtdhandtrhwere not detected in South Island samples, andV. parahaemolyticuswas detected in just 1/21 dredge oyster and 2/16 mussel samples. Numbers ofV. parahaemolyticusorganisms increased when seawater temperatures were high, the season when most commercial shellfish-growing areas are not harvested. The numbers ofV. parahaemolyticusorganisms in samples exceeded 1,000 MPN/g only when the seawater temperatures exceeded 19°C, so this environmental parameter could be used as a trigger warning of potential hazard. There is some evidence that the totalV. parahaemolyticusnumbers increased compared with those reported from a previous 1981 to 1984 study, but the analytical methods differed significantly.

scholarly journals Establishment and Validation of RNA-Based Predictive Models for Understanding Survival of Vibrio parahaemolyticus in Oysters Stored at Low Temperatures

2017 ◽  
Vol 83 (6) ◽  
Author(s):  
Chao Liao ◽  
Yong Zhao ◽  
Luxin Wang
Keyword(s):  
Real Time ◽  
Predictive Models ◽  
Vibrio Parahaemolyticus ◽  
False Negative ◽  
Bacterial Inactivation ◽  
Rt Pcr ◽  
Content Type ◽  
Low Temperature Storage ◽  
Reverse Transcription Pcr ◽  
Negative Results

ABSTRACT This study developed RNA-based predictive models describing the survival of Vibrio parahaemolyticus in Eastern oysters (Crassostrea virginica) during storage at 0, 4, and 10°C. Postharvested oysters were inoculated with a cocktail of five V. parahaemolyticus strains and were then stored at 0, 4, and 10°C for 21 or 11 days. A real-time reverse transcription-PCR (RT-PCR) assay targeting expression of the tlh gene was used to evaluate the number of surviving V. parahaemolyticus cells, which was then used to establish primary molecular models (MMs). Before construction of the MMs, consistent expression levels of the tlh gene at 0, 4, and 10°C were confirmed, and this gene was used to monitor the survival of the total V. parahaemolyticus cells. In addition, the tdh and trh genes were used for monitoring the survival of virulent V. parahaemolyticus. Traditional models (TMs) were built based on data collected using a plate counting method. From the MMs, V. parahaemolyticus populations had decreased 0.493, 0.362, and 0.238 log10 CFU/g by the end of storage at 0, 4, and 10°C, respectively. Rates of reduction of V. parahaemolyticus shown in the TMs were 2.109, 1.579, and 0.894 log10 CFU/g for storage at 0, 4, and 10°C, respectively. Bacterial inactivation rates (IRs) estimated with the TMs (−0.245, −0.152, and −0.121 log10 CFU/day, respectively) were higher than those estimated with the MMs (−0.134, −0.0887, and −0.0732 log10 CFU/day, respectively) for storage at 0, 4, and 10°C. Higher viable V. parahaemolyticus numbers were predicted using the MMs than using the TMs. On the basis of this study, RNA-based predictive MMs are the more accurate and reliable models and can prevent false-negative results compared to TMs. IMPORTANCE One important method for validating postharvest techniques and for monitoring the behavior of V. parahaemolyticus is to establish predictive models. Unfortunately, previous predictive models established based on plate counting methods or on DNA-based PCR can underestimate or overestimate the number of surviving cells. This study developed and validated RNA-based molecular predictive models to describe the survival of V. parahaemolyticus in oysters during low-temperature storage (0, 4, and 10°C). The RNA-based predictive models show the advantage of being able to count all of the culturable, nonculturable, and stressed cells. By using primers targeting the tlh gene and pathogenesis-associated genes (tdh and trh), real-time RT-PCR can evaluate the total surviving V. parahaemolyticus population as well as differentiate the pathogenic ones from the total population. Reliable and accurate predictive models are very important for conducting risk assessment and management of pathogens in food.

scholarly journals Evaluation of Two Direct Plating Methods Using Nonradioactive Probes for Enumeration of Vibrio parahaemolyticus in Oysters

2001 ◽  
Vol 67 (2) ◽  
pp. 721-724 ◽  
Author(s):  
J. A. Gooch ◽  
A. DePaola ◽  
C. A. Kaysner ◽  
D. L. Marshall
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Most Probable Number ◽  
Mobile Bay ◽  
Probable Number ◽  
Direct Plating ◽  
Hemolysin Gene ◽  
Highly Correlated ◽  
Species Specific ◽  
Labeled Probe ◽  
Zero Time

ABSTRACT Oysters (Crassostrea virginica) were collected monthly from May 1998 to April 1999 from Mobile Bay, Ala., and analyzed to determine Vibrio parahaemolyticus densities at zero time and after 5, 10, and 24 h of postharvest storage at 26°C. After 24 h of storage at 26°C, oysters were transferred to a refrigerator at 3°C and then analyzed 14 to 17 days later. TheV. parahaemolyticus numbers were determined by the most-probable-number procedure using alkaline phosphatase-labeled DNA probe VPAP, which targets the species-specific thermolabile hemolysin gene (tlh), to identify suspect isolates (MPN-VPAP procedure). Two direct plating methods, one using a VPAP probe (Direct-VPAP) and one using a digoxigenin-labeled probe (Direct-VPDig) to identify suspect colonies, were compared to the MPN-VPAP procedure. The results of the Direct-VPAP and Direct-VPDig techniques were highly correlated (r = 0.91), as were the results of the Direct-VPAP and MPN-VPAP procedures (r = 0.91). The correlation between the Direct-VPDig and MPN-VPAP results was 0.85. The two direct plating methods in which nonradioactive DNA probes were used were equivalent to the MPN-VPAP procedure for identification of totalV. parahaemolyticus, and they were more rapid and less labor-intensive.

scholarly journals Persistence of Vibrio parahaemolyticus in the Pacific Oyster, Crassostrea gigas, Is a Multifactorial Process Involving Pili and Flagella but Not Type III Secretion Systems or Phase Variation

2013 ◽  
Vol 79 (10) ◽  
pp. 3303-3305 ◽  
Author(s):  
Alisha M. Aagesen ◽  
Sureerat Phuvasate ◽  
Yi-Cheng Su ◽  
Claudia C. Häse
Keyword(s):  
Type Iii Secretion ◽  
Vibrio Parahaemolyticus ◽  
Phase Variation ◽  
Type I ◽  
Secretion Systems ◽  
Content Type ◽  
Type Iii ◽  
Type Iv ◽  
Pacific Oysters ◽  
Type Iii Secretion Systems

ABSTRACTVibrio parahaemolyticuscan resist oyster depuration, suggesting that it possesses specific factors for persistence. We show that type I pili, type IV pili, and both flagellar systems contribute toV. parahaemolyticuspersistence in Pacific oysters whereas type III secretion systems and phase variation do not.

scholarly journals Rapid Proliferation of Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae during Freshwater Flash Floods in French Mediterranean Coastal Lagoons

2015 ◽  
Vol 81 (21) ◽  
pp. 7600-7609 ◽  
Author(s):  
Kevin Esteves ◽  
Dominique Hervio-Heath ◽  
Thomas Mosser ◽  
Claire Rodier ◽  
Marie-George Tournoud ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Coastal Lagoons ◽  
Flash Floods ◽  
Low Flow ◽  
Most Probable Number ◽  
Abrupt Decrease ◽  
Probable Number ◽  
Content Type

ABSTRACTVibrio parahaemolyticus,Vibrio vulnificus, andVibrio choleraeof the non-O1/non-O139 serotype are present in coastal lagoons of southern France. In these Mediterranean regions, the rivers have long low-flow periods followed by short-duration or flash floods during and after heavy intense rainstorms, particularly at the end of the summer and in autumn. These floods bring large volumes of freshwater into the lagoons, reducing their salinity. Water temperatures recorded during sampling (15 to 24°C) were favorable for the presence and multiplication of vibrios. In autumn 2011, before heavy rainfalls and flash floods, salinities ranged from 31.4 to 36.1‰ and concentrations ofV. parahaemolyticus,V. vulnificus, andV. choleraevaried from 0 to 1.5 × 103most probable number (MPN)/liter, 0.7 to 2.1 × 103MPN/liter, and 0 to 93 MPN/liter, respectively. Following heavy rainstorms that generated severe flash flooding and heavy discharge of freshwater, salinity decreased, reaching 2.2 to 16.4‰ within 15 days, depending on the site, with a concomitant increase inVibrioconcentration to ca. 104MPN/liter. The highest concentrations were reached with salinities between 10 and 20‰ forV. parahaemolyticus, 10 and 15‰ forV. vulnificus, and 5 and 12‰ forV. cholerae. Thus, an abrupt decrease in salinity caused by heavy rainfall and major flooding favored growth of human-pathogenicVibriospp. and their proliferation in the Languedocian lagoons. Based on these results, it is recommended that temperature and salinity monitoring be done to predict the presence of theseVibriospp. in shellfish-harvesting areas of the lagoons.

Effects of Electrolyzed Oxidizing Water Treatment on Reducing Vibrio parahaemolyticus and Vibrio vulnificus in Raw Oysters

2006 ◽  
Vol 69 (8) ◽  
pp. 1829-1834 ◽  
Author(s):  
TINGTING REN ◽  
YI-CHENG SU
Keyword(s):  
Water Treatment ◽  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Safety Concern ◽  
Most Probable Number ◽  
Probable Number ◽  
Pacific Oysters ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Pure Cultures

Contamination of Vibrio parahaemolyticus and Vibrio vulnificus in oysters is a food safety concern. This study investigated effects of electrolyzed oxidizing (EO) water treatment on reducing V. parahaemolyticus and V. vulnificus in laboratory-contaminated oysters. EO water exhibited strong antibacterial activity against V. parahaemolyticus and V. vulnificus in pure cultures. Populations of V. parahaemolyticus (8.74 × 107 CFU/ml) and V. vulnificus (8.69 × 107 CFU/ml) decreased quickly in EO water containing 0.5% NaCl to nondetectable levels (>6.6 log reductions) within 15 s. Freshly harvested Pacific oysters were inoculated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus at levels of 104 and 106 most probable number (MPN)/g and treated with EO water (chlorine, 30 ppm; pH 2.82; oxidation-reduction potential, 1131 mV) containing 1% NaCl at room temperature. Reductions of V. parahaemolyticus and V. vulnificus in oysters were determined at 0 (before treatment), 2, 4, 6, and8hof treatment. Holding oysters inoculated with V. parahaemolyticus or V. vulnificus in the EO water containing 1% NaCl for 4 to 6 h resulted in significant (P < 0.05) reductions of V. parahaemolyticus and V. vulnificus by 1.13 and 1.05 log MPN/g, respectively. Extended exposure (>12 h) of oysters in EO water containing high levels of chlorine (>30 ppm) was found to be detrimental to oysters. EO water could be used as a postharvest treatment to reduce Vibrio contamination in oysters. However, treatment should be limited to 4 to6hto avoid death of oysters. Further studies are needed to determine effects of EO water treatment on sensory characteristics of oysters.

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