Distribution of Vibrio vulnificus in the Chesapeake Bay

Quantification of Climate Footprints of Vibrio vulnificus in Coastal Human Communities of the United States Gulf Coast

The incidence of vibriosis is rising globally with evidence of climate variability influencing environmental processes that support growth of pathogenic Vibrio spp. The waterborne pathogen, Vibrio vulnificus can invade wounds and has one of the highest case fatality rates in humans. The bacterium cannot be eradicated from the aquatic environment, hence climate driven environmental conditions enhancing growth and dissemination of V. vulnificus need to be understood to provide preemptive assessment of its presence and distribution in aquatic systems. To achieve this objective, satellite remote sensing was employed to quantify the association of sea surface temperature (SST) and chlorophyll-a (chl-a) in locations with reported V. vulnificus infections. Monthly analysis was done in two populated regions of the Gulf of Mexico-Tampa Bay, Florida, and Galveston Bay, Texas. Results indicate warm water, characterized by a 2-month lag in SST, high concentration of phytoplankton, proxied for zooplankton using 1 month lagged chl-a values, was statistically linked to higher odds of V. vulnificus infection in the human population. Identification of climate and ecological processes thresholds is concluded to be useful for development of an heuristic prediction system designed to determine risk of infection for coastal populations.

Tracking Vibrio: population dynamics and ecology of Vibrio parahaemolyticus and V. vulnificus in an Alabama estuary

Vibrio is a genus of halophilic, gram-negative bacteria found in estuaries around the globe. Integral parts of coastal cultures often involve contact with vectors of pathogenic Vibrio spp. (e.g., consuming raw shellfish). High rates of mortality from certain Vibrio spp. infections demonstrate the need for an improved understanding of Vibrio spp. dynamics in estuarine regions. Our study assessed meteorological, hydrographic, and biological correlates of Vibrio parahaemolyticus and V. vulnificus at 10 sites in the Eastern Mississippi Sound System (EMSS) from April to October 2019. During the sampling period, median abundances of V. parahaemolyticus and V. vulnificus were 2.31 log MPN/L and 2.90 log MPN/L, respectively. Vibrio spp. dynamics were largely driven by site-based variation, with sites closest to freshwater inputs having the highest abundances. The E-W wind scalar, which affects Ekman transport, was a novel Vibrio spp. correlate observed. A potential salinity effect on bacterial-particle associations was identified, where V. vulnificus was associated with larger particles in conditions outside of their optimal salinity. Additionally, V. vulnificus abundances were correlated to those of harmful algal species that did not dominate community chlorophyll. Correlates from this study may be used to inform the next iteration of regionally predictive Vibrio models and may lend additional insight to Vibrio spp. ecology in similar systems.

IMPORTANCE

Vibrio spp. are bacteria found in estuaries worldwide; some species can cause illness and infections in humans. Relationships between Vibrio spp. abundance, salinity, and temperature are well documented, but correlations to other environmental parameters are less understood. This study identifies unique correlates (e.g., E-W wind scalar and harmful algal species) that could potentially inform the next iteration of predictive Vibrio models for the EMSS region. Additionally, these correlates may allow existing environmental monitoring efforts to be leveraged in providing data inputs for future Vibrio risk models. An observed correlation between salinity and V. vulnificus/particle-size associations suggests that predicted environmental changes may affect the abundance of Vibrio spp. in certain reservoirs, which may alter which vectors present the greatest vibrio risk.

A study into the diversity of coral-associated bacteria using culture-dependent and culture-independent approaches in coral Dipsastraea favus from the Gulf of Kutch

Corals harbour ~25 % of the marine diversity referring to biodiversity hotspots in marine ecosystems. Global efforts to find ways to restore the coral reef ecosystem from various threats can be complemented by studying coral-associated bacteria. Coral-associated bacteria are vital components of overall coral wellbeing. We explored the bacterial diversity associated with coral Dipsastraea favus (D. favus) collected from the Gulf of Kutch, India, using both culture-dependent and metagenomic approaches. In both approaches, phylum Proteobacteria, Firmicutes, and Actinobacteria predominated, comprising the genera Vibrio, Bacillus, Shewanella, Pseudoalteromonas, Exiguobacterium and Streptomyces. Moreover, the majority of culturable isolates showed multiple antibiotic resistance index ≥0.2. In this study, specific bacterial diversity associated with coral sp. D. favus and its possible role in managing coral health was established. Almost 43 strains from the samples were successfully cultured, creating a base for exploring these microbes for their potential use in coral conservation methods.

Genomic diversity of Vibrio spp. and metagenomic analysis of pathogens in Florida Gulf coastal waters following Hurricane Ian

IMPORTANCE

Evidence suggests warming temperatures are associated with the spread of potentially pathogenic Vibrio spp. and the emergence of human disease globally. Following Hurricane Ian, the State of Florida reported a sharp increase in the number of reported Vibrio spp. infections and deaths. Hence, monitoring of pathogens, including vibrios, and environmental parameters influencing their occurrence is critical to public health. Here, DNA sequencing was used to investigate the genomic diversity of Vibrio parahaemolyticus and Vibrio vulnificus, both potential human pathogens, in Florida coastal waters post Hurricane Ian, in October 2022. Additionally, the microbial community of water samples was profiled to detect the presence of Vibrio spp. and other microorganisms (bacteria, fungi, protists, and viruses) present in the samples. Long-term environmental data analysis showed changes in environmental parameters during and after Ian were optimal for the growth of Vibrio spp. and related pathogens. Collectively, results will be used to develop predictive risk models during climate change.

The impact of global warming on the signature virulence gene, thermolabile hemolysin, of Vibrio parahaemolyticus

IMPORTANCE

In this study, Vibrio parahaemolyticus strains were collected from a large number of aquatic products globally and found that temperature has an impact on the virulence of these bacteria. As global temperatures rise, mutations in a gene marker called thermolabile hemolysin (tlh) also increase. This suggests that environmental isolates adapt to the warming environment and become more pathogenic. The findings can help in developing tools to analyze and monitor these bacteria as well as assess any link between climate change and vibrio-associated diseases, which could be used for forecasting outbreaks associated with them.

Tools to Enumerate and Predict Distribution Patterns of Environmental Vibrio vulnificus and Vibrio parahaemolyticus

Vibrio vulnificus (Vv) and Vibrio parahaemolyticus (Vp) are water- and foodborne bacteria that can cause several distinct human diseases, collectively called vibriosis. The success of oyster aquaculture is negatively impacted by high Vibrio abundances. Myriad environmental factors affect the distribution of pathogenic Vibrio, including temperature, salinity, eutrophication, extreme weather events, and plankton loads, including harmful algal blooms. In this paper, we synthesize the current understanding of ecological drivers of Vv and Vp and provide a summary of various tools used to enumerate Vv and Vp in a variety of environments and environmental samples. We also highlight the limitations and benefits of each of the measurement tools and propose example alternative tools for more specific enumeration of pathogenic Vv and Vp. Improvement of molecular methods can tighten better predictive models that are potentially important for mitigation in more controlled environments such as aquaculture.

Environmental Factors Associated with Incidence and Distribution of V. parahaemolyticus and V. vulnificus in Chesapeake Bay, Maryland, USA: A three-year case study

Members of the genus Vibrio are ecologically significant bacteria native to aquatic ecosystems globally, and a few can cause diseases in humans. Vibrio-related illnesses have increased in recent years, primarily attributed to changing environmental conditions. Therefore, understanding the role of environmental factors in the occurrence and growth of pathogenic strains is crucial for public health. Water, oyster, and sediment samples were collected between 2009 and 2012 from Chester River and Tangier Sound sites in Chesapeake Bay, Maryland, USA, to investigate the relationship between water temperature, salinity, and chlorophyll with the incidence and distribution of Vibrio parahaemolyticus (VP) and Vibrio vulnificus (VV). Odds ratio analysis was used to determine association between the likelihood of VP and VV presence and these environmental variables. Results suggested that water temperature threshold of 20°C or higher was associated with an increased risk, favoring the incidence of Vibrio spp. A significant difference in salinity was observed between the two sampling sites, with distinct ranges showing high odds ratio for Vibrio incidence, especially in water and sediment, emphasizing the impact of salinity on VP and VV incidence and distribution. Notably, salinity between 9-20 PPT consistently favored the Vibrio incidence across all samples. Relationship between chlorophyll concentrations and VP and VV incidence varied depending on sample type. However, chlorophyll range of 0-10 μg/L was identified as critical in oyster samples for both vibrios. Analysis of odds ratios for water samples demonstrated consistent outcomes across all environmental parameters, indicating water samples offer a more reliable indicator of Vibrio spp. incidence.

Impact of pathogenic bacterial communities present in wastewater on aquatic organisms: Application of nanomaterials for the removal of these pathogens

Contaminated wastewater (WW) can cause severe hazards to numerous delicate ecosystems and associated life forms. In addition, human health is negatively impacted by the presence of microorganisms in water. Multiple pathogenic microorganisms in contaminated water, including bacteria, fungi, yeast, and viruses, are vectors for several contagious diseases. To avoid the negative impact of these pathogens, WW must be free from pathogens before being released into stream water or used for other reasons. In this review article, we have focused on pathogenic bacteria in WW and summarized the impact of the different types of pathogenic bacteria on marine organisms. Moreover, we presented a variety of physical and chemical techniques that have been developed to provide a pathogen-free aquatic environment. Among the techniques, membrane-based techniques for trapping hazardous biological contaminants are gaining popularity around the world. Besides, novel and recent advancements in nanotechnological science and engineering suggest that many waterborne pathogens could be inactivated using nano catalysts, bioactive nanoparticles, nanostructured catalytic membranes, nanosized photocatalytic structures, and electrospun nanofibers and processes have been thoroughly examined.

Vibrio Infections and the Twenty-First Century

The Vibrionaceae is a highly diverse family of aquatic bacteria. Some members of this ubiquitous group can cause a variety of diseases in humans ranging from cholera caused by Vibrio cholerae, severe septicemia caused by Vibrio vulnificus, to acute gastroenteritis by Vibrio parahaemolyticus. Planet Earth is experiencing unprecedented changes of planetary scale associated with climate change. These environmental perturbations paired with overpopulation and pollution are increasing the distribution of pathogenic Vibrios and exacerbating the risk of causing infections. In this chapter, we discuss various aspects of Vibrio infections within the context of the twenty-first century with a major emphasis on the aforementioned pathogenic species. Overall, we believe that the twenty-first century is posed to be both one full of challenges due to the rise of these pathogens, and also a catalyst for innovative and groundbreaking discoveries.

Characterization of Prophylactic Antimicrobial Therapy Practices for Patients With Marine-Associated Injuries in the Emergency Department

BACKGROUND

Centers for Disease Control and Prevention (CDC) recommendations for the treatment of marine-associated wound infections include empiric coverage for Vibrio species with a combination of a third-generation cephalosporin and doxycycline. These recommendations are based on limited data and it remains unclear if this regimen is also indicated for prophylaxis.

OBJECTIVE

The purpose of this analysis was to assess the antibiotic regimens used in the emergency department (ED) for prophylaxis of marine-associated injuries relative to the CDC recommendations and evaluate any clinical impact.

METHODS

A retrospective review evaluated adult patients discharged from the ED over a 4-year period with an antibiotic prescription following an injury with marine exposure.

RESULTS

114 patients were included in the analysis. The majority of patients were < 40 years of age with no previous medical history and presented after sustaining a laceration secondary to oyster shells. 97.4% received prophylactic antibiotic therapy that did not match the CDC recommendations, with the majority receiving doxycycline monotherapy (82%). A 1.8% 30-day ED revisit rate was noted with 2 patients returning for therapy failure. No patients were admitted to the hospital within 30 days and no documented adverse effects related to antibiotic therapy were noted.

CONCLUSION

Current prophylactic antibiotic prescribing practices diverge from the current CDC recommendations for the treatment of marine-associated infections, however, an effect secondary to these variations was not observed. Further investigations of prophylaxis against Vibrio infections in low-risk patients is warranted to limit collateral damage and improve antimicrobial stewardship in the ED.

Vibrio vulnificus sepsis after shrimp shelling in a patient with preexisting primary biliary cholangitis: a case report

BACKGROUND

Vibrio vulnificus is typically present in seawater, fish, and shellfish, and is known to cause severe sepsis, particularly in patients with liver diseases such as cirrhosis. V. vulnificus is one of the most dangerous waterborne pathogens, and infection mainly occurs in western Japan during the summer, with an increased fatality rate. Herein, we report the case of a patient with primary biliary cholangitis and sepsis caused by V. vulnificus infection sustained through shrimp shelling.

CASE PRESENTATION

An 82-year-old Japanese Asian woman with no medical history or underlying disease developed redness, swelling, and pain, which extended from the right fingers to the upper arm. A diagnosis of sepsis due to cellulitis was made. Blood culture detected V. vulnificus; thus, minocycline was administered in addition to meropenem. The disease course was uneventful, and the patient was discharged on day 28 of hospitalization. Symptoms in the right upper arm developed 1 day after the patient shelled a large number of shrimp; therefore, the infection route was assumed to be through wounds sustained during shrimp shelling. We suspected liver disease and measured serum anti-mitochondrial M2 antibody levels, leading to the diagnosis of primary biliary cholangitis.

CONCLUSIONS

As in this case, small wounds caused by handling fish and shrimp are a potential source of infection. Patients with severe V. vulnificus infection should be thoroughly assessed for the presence of liver diseases such as primary biliary cholangitis.

Optimum environmental conditions controlling prevalence of vibrio parahaemolyticus in marine environment

This literature review presents major environmental indicators and their optimum variation ranges for the prevalence of Vibrio parahaemolyticus in the marine environment by critically reviewing and statistically analyzing more than one hundred studies from countries around the world. Results of this review indicated that the prevalence of Vibrio parahaemolyticus in the marine environment is primarily responsive to favorable environmental conditions that are described with environmental indicators. The importance of environmental indicators to the prevalence of Vibrio parahaemolyticus can be ranked from the highest to lowest as Sea Surface Temperature (SST), salinity, pH, chlorophyll a, and turbidity, respectively. It was also found in this study that each environmental indicator has an optimum variation range favoring the prevalence of Vibrio parahaemolyticus. Specifically, the SST range of 25.67 ± 2 °C, salinity range of 27.87 ± 3 ppt, and pH range of 7.96 ± 0.1 were found to be the optimum conditions for the prevalence of Vibrio parahaemolyticus. High vibrio concentrations were also observed in water samples with the chlorophyll a range of 16-25 μg/L. The findings provide new insights into the importance of environmental indicators and their optimum ranges, explaining not only the existence of both positive and negative associations reported in the literature but also the dynamic associations between the Vibrio presence and its environmental drivers.

Refining real-time predictions of Vibrio vulnificus concentrations in a tropical urban estuary by incorporating dissolved organic matter dynamics

The south shore of O'ahu, Hawai'i is one of the most visited coastal tourism areas in the United States with some of the highest instances of recreational waterborne disease. A population of the pathogenic bacterium Vibrio vulnificus lives in the estuarine Ala Wai Canal in Honolulu which surrounds the heavily populated tourism center of Waikīkī. We developed a statistical model to predict V. vulnificus dynamics in this system using environmental measurements from moored oceanographic and atmospheric sensors in real time. During a year-long investigation, we analyzed water from 9 sampling events at 3 depths and 8 sites along the canal (n = 213) for 36 biogeochemical variables and V. vulnificus concentration using quantitative polymerase chain reaction (qPCR) of the hemolysin A gene (vvhA). The best multiple linear regression model of V. vulnificus concentration, explaining 80% of variation, included only six predictors: 5-day average rainfall preceding water sampling, daily maximum air temperature, water temperature, nitrate plus nitrite, and two metrics of humic dissolved organic matter (DOM). We show how real-time predictions of V. vulnificus concentration can be made using these models applied to the time series of water quality measurements from the Pacific Islands Ocean Observing System (PacIOOS) as well as the PacIOOS plume model based on the Waikīkī Regional Ocean Modeling System (ROMS) products. These applications highlight the importance of including DOM variables in predictive modeling of V. vulnificus and the influence of rain events in elevating nearshore concentrations of V. vulnificus. Long-term climate model projections of locally downscaled monthly rainfall and air temperature were used to predict an overall increase in V. vulnificus concentration of approximately 2- to 3-fold by 2100. Improving these predictive models of microbial populations is critical for management of waterborne pathogen risk exposure, particularly in the wake of a changing global climate.

[Bacterial hepatobiliary infections : Pathogen spectrum, antimicrobial resistance and current treatment concepts]

Ascending cholangitis and pyogenic liver abscesses are acute febrile bacterial hepatobiliary diseases. Nowadays they frequently occur in patients with structural changes of the biliary system and are usually treated by a combination of interventional drainage procedures and antimicrobial therapy. While Gram-negative Enterobacterales were identified as major causes in the past, biliary tract interventions and antibiotic exposure have contributed to an increase in enterococcal species and extended spectrum beta-lactamase (ESBL)-producing Enterobacterales. When selecting an appropriate empirical treatment the treating internist must consider local and individual risk factors for antimicrobial resistance in addition to pharmacokinetic aspects and disease severity to reduce the likelihood of treatment failure.

Vibrio spp.: Life Strategies, Ecology, and Risks in a Changing Environment

Vibrios are ubiquitous bacteria in aquatic systems, especially marine ones, and belong to the Gammaproteobacteria class, the most diverse class of Gram-negative bacteria. The main objective of this review is to update the information regarding the ecology of Vibrio species, and contribute to the discussion of their potential risk in a changing environment. As heterotrophic organisms, Vibrio spp. live freely in aquatic environments, from marine depths to the surface of the water column, and frequently may be associated with micro- and macroalgae, invertebrates, and vertebrates such as fish, or live in symbiosis. Some Vibrio spp. are pathogenic to humans and animals, and there is evidence that infections caused by vibrios are increasing in the world. This rise may be related to global changes in human behavior (increases in tourism, maritime traffic, consumption of seafood, aquaculture production, water demand, pollution), and temperature. Most likely in the future, Vibrio spp. in water and in seafood will be monitored in order to safeguard human and animal health. Regulators of the microbiological quality of water (marine and freshwater) and food for human and animal consumption, professionals involved in marine and freshwater production chains, consumers and users of aquatic resources, and health professionals will be challenged to anticipate and mitigate new risks.

Coupled DNA-labeling and sequencing approach enables the detection of viable-but-non-culturable Vibrio spp. in irrigation water sources in the Chesapeake Bay watershed

Nontraditional irrigation water sources (e.g., recycled water, brackish water) may harbor human pathogens, including Vibrio spp., that could be present in a viable-but-nonculturable (VBNC) state, stymieing current culture-based detection methods. To overcome this challenge, we coupled 5-bromo-2'-deoxyuridine (BrdU) labeling, enrichment techniques, and 16S rRNA sequencing to identify metabolically-active Vibrio spp. in nontraditional irrigation water (recycled water, pond water, non-tidal freshwater, and tidal brackish water). Our coupled BrdU-labeling and sequencing approach revealed the presence of metabolically-active Vibrio spp. at all sampling sites. Whereas, the culture-based method only detected vibrios at three of the four sites. We observed the presence of V. cholerae, V. vulnificus, and V. parahaemolyticus using both methods, while V. aesturianus and V. shilonii were detected only through our labeling/sequencing approach. Multiple other pathogens of concern to human health were also identified through our labeling/sequencing approach including P. shigelloides, B. cereus and E. cloacae. Most importantly, 16S rRNA sequencing of BrdU-labeled samples resulted in Vibrio spp. detection even when our culture-based methods resulted in negative detection. This suggests that our novel approach can effectively detect metabolically-active Vibrio spp. that may have been present in a VBNC state, refining our understanding of the prevalence of vibrios in nontraditional irrigation waters.

Human Health and Ocean Pollution

Background

Pollution - unwanted waste released to air, water, and land by human activity - is the largest environmental cause of disease in the world today. It is responsible for an estimated nine million premature deaths per year, enormous economic losses, erosion of human capital, and degradation of ecosystems. Ocean pollution is an important, but insufficiently recognized and inadequately controlled component of global pollution. It poses serious threats to human health and well-being. The nature and magnitude of these impacts are only beginning to be understood.

Goals

(1) Broadly examine the known and potential impacts of ocean pollution on human health. (2) Inform policy makers, government leaders, international organizations, civil society, and the global public of these threats. (3) Propose priorities for interventions to control and prevent pollution of the seas and safeguard human health.

Methods

Topic-focused reviews that examine the effects of ocean pollution on human health, identify gaps in knowledge, project future trends, and offer evidence-based guidance for effective intervention.

Environmental Findings

Pollution of the oceans is widespread, worsening, and in most countries poorly controlled. It is a complex mixture of toxic metals, plastics, manufactured chemicals, petroleum, urban and industrial wastes, pesticides, fertilizers, pharmaceutical chemicals, agricultural runoff, and sewage. More than 80% arises from land-based sources. It reaches the oceans through rivers, runoff, atmospheric deposition and direct discharges. It is often heaviest near the coasts and most highly concentrated along the coasts of low- and middle-income countries. Plastic is a rapidly increasing and highly visible component of ocean pollution, and an estimated 10 million metric tons of plastic waste enter the seas each year. Mercury is the metal pollutant of greatest concern in the oceans; it is released from two main sources - coal combustion and small-scale gold mining. Global spread of industrialized agriculture with increasing use of chemical fertilizer leads to extension of Harmful Algal Blooms (HABs) to previously unaffected regions. Chemical pollutants are ubiquitous and contaminate seas and marine organisms from the high Arctic to the abyssal depths.

Ecosystem Findings

Ocean pollution has multiple negative impacts on marine ecosystems, and these impacts are exacerbated by global climate change. Petroleum-based pollutants reduce photosynthesis in marine microorganisms that generate oxygen. Increasing absorption of carbon dioxide into the seas causes ocean acidification, which destroys coral reefs, impairs shellfish development, dissolves calcium-containing microorganisms at the base of the marine food web, and increases the toxicity of some pollutants. Plastic pollution threatens marine mammals, fish, and seabirds and accumulates in large mid-ocean gyres. It breaks down into microplastic and nanoplastic particles containing multiple manufactured chemicals that can enter the tissues of marine organisms, including species consumed by humans. Industrial releases, runoff, and sewage increase frequency and severity of HABs, bacterial pollution, and anti-microbial resistance. Pollution and sea surface warming are triggering poleward migration of dangerous pathogens such as the Vibrio species. Industrial discharges, pharmaceutical wastes, pesticides, and sewage contribute to global declines in fish stocks.

Human Health Findings

Methylmercury and PCBs are the ocean pollutants whose human health effects are best understood. Exposures of infants in utero to these pollutants through maternal consumption of contaminated seafood can damage developing brains, reduce IQ and increase children's risks for autism, ADHD and learning disorders. Adult exposures to methylmercury increase risks for cardiovascular disease and dementia. Manufactured chemicals - phthalates, bisphenol A, flame retardants, and perfluorinated chemicals, many of them released into the seas from plastic waste - can disrupt endocrine signaling, reduce male fertility, damage the nervous system, and increase risk of cancer. HABs produce potent toxins that accumulate in fish and shellfish. When ingested, these toxins can cause severe neurological impairment and rapid death. HAB toxins can also become airborne and cause respiratory disease. Pathogenic marine bacteria cause gastrointestinal diseases and deep wound infections. With climate change and increasing pollution, risk is high that Vibrio infections, including cholera, will increase in frequency and extend to new areas. All of the health impacts of ocean pollution fall disproportionately on vulnerable populations in the Global South - environmental injustice on a planetary scale.

Conclusions

Ocean pollution is a global problem. It arises from multiple sources and crosses national boundaries. It is the consequence of reckless, shortsighted, and unsustainable exploitation of the earth's resources. It endangers marine ecosystems. It impedes the production of atmospheric oxygen. Its threats to human health are great and growing, but still incompletely understood. Its economic costs are only beginning to be counted.Ocean pollution can be prevented. Like all forms of pollution, ocean pollution can be controlled by deploying data-driven strategies based on law, policy, technology, and enforcement that target priority pollution sources. Many countries have used these tools to control air and water pollution and are now applying them to ocean pollution. Successes achieved to date demonstrate that broader control is feasible. Heavily polluted harbors have been cleaned, estuaries rejuvenated, and coral reefs restored.Prevention of ocean pollution creates many benefits. It boosts economies, increases tourism, helps restore fisheries, and improves human health and well-being. It advances the Sustainable Development Goals (SDG). These benefits will last for centuries.

Recommendations

World leaders who recognize the gravity of ocean pollution, acknowledge its growing dangers, engage civil society and the global public, and take bold, evidence-based action to stop pollution at source will be critical to preventing ocean pollution and safeguarding human health.Prevention of pollution from land-based sources is key. Eliminating coal combustion and banning all uses of mercury will reduce mercury pollution. Bans on single-use plastic and better management of plastic waste reduce plastic pollution. Bans on persistent organic pollutants (POPs) have reduced pollution by PCBs and DDT. Control of industrial discharges, treatment of sewage, and reduced applications of fertilizers have mitigated coastal pollution and are reducing frequency of HABs. National, regional and international marine pollution control programs that are adequately funded and backed by strong enforcement have been shown to be effective. Robust monitoring is essential to track progress.Further interventions that hold great promise include wide-scale transition to renewable fuels; transition to a circular economy that creates little waste and focuses on equity rather than on endless growth; embracing the principles of green chemistry; and building scientific capacity in all countries.Designation of Marine Protected Areas (MPAs) will safeguard critical ecosystems, protect vulnerable fish stocks, and enhance human health and well-being. Creation of MPAs is an important manifestation of national and international commitment to protecting the health of the seas.

The transcriptome analysis of the Arabidopsis thaliana in response to the Vibrio vulnificus by RNA-sequencing

Because of the recent increase in the demand for fresh produce, contamination of raw food products has become an issue. Foodborne diseases are frequently caused by the infection of leguminous plants by human bacterial pathogens. Moreover, contamination by Vibrio cholerae, closely related with Vibrio vulnificus, has been reported in plants and vegetables. Here, we investigated the possibility of Vibrio vulnificus 96-11-17M, an opportunistic human pathogen, to infect and colonize Arabidopsis thaliana plants, resulting in typical disease symptoms at 5 and 7 days post-inoculation in vitro and in planta under artificial and favorable conditions, respectively. RNA-Seq analysis revealed 5,360, 4,204, 4,916 and 3,741 differentially expressed genes (DEGs) at 12, 24, 48 and 72 h post-inoculation, respectively, compared with the 0 h time point. Gene Ontology analysis revealed that these DEGs act in pathways responsive to chemical and hormone stimuli and plant defense. The expression of genes involved in salicylic acid (SA)-, jasmonic acid (JA)- and ethylene (ET)-dependent pathways was altered following V. vulnificus inoculation. Genetic analyses of Arabidopsis mutant lines verified that common pathogen-associated molecular pattern (PAMP) receptors perceive the V. vulnificus infection, thus activating JA and ET signaling pathways. Our data indicate that the human bacterial pathogen V. vulnificus 96-11-17M modulates defense-related genes and host defense machinery in Arabidopsis thaliana under favorable conditions.

Calcium-dependent site-switching regulates expression of the atypical iam pilus locus in Vibrio vulnificus

The opportunistic human pathogen Vibrio vulnificus inhabits warm coastal waters and asymptomatically colonizes seafood, most commonly oysters. We previously characterized an isolate that exhibited greater biofilm formation, aggregation and oyster colonization than its parent. This was due, in part, to the production of a Type IV Tad pilus (Iam). However, the locus lacked key processing and regulatory genes required for pilus production. Here, we identify a pilin peptidase iamP, and LysR-type regulator (LRTR) iamR, that fulfil these roles and show that environmental calcium, which oysters enrich for shell repair and growth, regulates iam expression. The architecture of the iam locus differs from the classical LRTR paradigm and requires an additional promoter to be integrated into the regulatory network. IamR specifically recognized the iamR promoter (P_iamR ) and the intergenic iamP-iamA region (P_iamP-A ). P_iamR exhibited classical negative auto-regulation but, strikingly, IamR inversely regulated the divergent iamP and iamA promoters in a calcium-dependent manner. Moreover, expression of the c-di-GMP and calcium-regulated, biofilm-promoting brp exopolysaccharide was IamA-dependent. These results support a scenario in which the calcium-enriched oyster environment triggers IamP-mediated processing of prepilin amassed in the periplasm for rapid pilin elaboration and subsequent BRP production to promote colonization.

Impact of Climate Change on Vibrio vulnificus Abundance and Exposure Risk

Vibrio species are marine bacteria that occur in estuaries worldwide; many are virulent human pathogens with high levels of antibiotic resistance. The average annual incidence of all Vibrio infections has increased by 41% between 1996 and 2005. V. vulnificus (Vv), a species associated with shellfish and occurring in the US Southeast, has ranges of temperature (16-33 °C) and salinity (5-20 ppt) dependencies for optimal growth. Increased water temperatures caused by atmospheric warming and increased salinity gradients caused by sea level rise raise concerns for the effect of climate change on the geographic range of Vv and the potential for increased exposure risk. This research combined monthly field sampling, laboratory analysis, and modeling to identify the current occurrence of Vv in the Winyah Bay estuary (South Carolina, USA) and assess the possible effects of climate change on future geographic range and exposure risk in the estuary. Vv concentrations ranged from 0 to 58 colony forming units (CFU)/mL, salinities ranged from 0 to 28 ppt, and temperature from 18 to 31 °C. A significant empirical relationship was found between Vv concentration and salinity and temperature that fit well with published optimal ranges for growth for these environmental parameters. These results, when coupled with an existing model of future specific conductance, indicated that sea level rise has a greater impact on exposure risk than temperature increases in the estuary. Risk increased by as much as four times compared to current conditions with the largest temporally widespread increase at the most upriver site where currently there is minimal risk.

Vibrio responses to extracytoplasmic stress

A critical factor for bacterial survival in any environment is the ability to sense and respond appropriately to any stresses encountered. This is especially important for bacteria that inhabit environments that are constantly changing, or for those that inhabit more than one biological niche. Vibrio species are unique in that they are aquatic organisms, and must adapt to ever-changing temperatures, salinity levels and nutrient concentrations. In addition, many species of Vibrio colonize other organisms, and must also deal with components of the host immune response. Vibrio infections of humans and other organisms have become more common in recent years, due to increasing water temperatures in many parts of the world. Therefore, understanding how these ubiquitous marine bacteria adapt to their changing environments is of importance. In this review, we discuss some of the ways that Vibrios sense and respond to the variety of stresses that negatively affect the bacterial cell envelope. Specifically, we will focus on what is currently known about the σ^E response, the Cpx response and the contributions of OmpU to extracytoplasmic stress relief.

A Tad pilus promotes the establishment and resistance of Vibrio vulnificus biofilms to mechanical clearance

Vibrio vulnificus is autochthonous to estuaries and warm coastal waters. Infection occurs via open wounds or ingestion, where its asymptomatic colonization of seafood, most infamously oysters, provides a gateway into the human food chain. Colonization begins with initial surface contact, which is often mediated by bacterial surface appendages called pili. Type IV Tad pili are widely distributed in the Vibrionaceae, but evidence for a physiological role for these structures is scant. The V. vulnificus genome codes for three distinct tad loci. Recently, a positive correlation was demonstrated between the expression of tad-3 and the phenotypes of a V. vulnificus descendent (NT) that exhibited increased biofilm formation, auto-aggregation, and oyster colonization relative to its parent. However, the mechanism by which tad pilus expression promoted these phenotypes was not determined. Here, we show that deletion of the tad pilin gene (flp) altered the near-surface motility profile of NT cells from high curvature, orbital retracing patterns characteristic of cells actively probing the surface to low curvature traces indicative of wandering and diminished bacteria-surface interactions. The NT flp pilin mutant also exhibited decreased initial surface attachment, attenuated auto-aggregation and formed fragile biofilms that disintegrated under hydrodynamic flow. Thus, the tad-3 locus, designated iam, promoted initial surface attachment, auto-aggregation and resistance to mechanical clearance of V. vulnificus biofilms. The prevalence of tad loci in the Vibrionaceae suggests that they may play equally important roles in other family members.

Assessment of Fecal Indicator Bacteria and Potential Pathogen Co-Occurrence at a Shellfish Growing Area

Routine monitoring of shellfish growing waters for bacteria indicative of human sewage pollution reveals little about the bacterial communities that co-occur with these indicators. This study investigated the bacterial community, potential pathogens, and fecal indicator bacteria in 40 water samples from a shellfish growing area in the Chesapeake Bay, USA. Bacterial community composition was quantified with deep sequencing of 16S rRNA gene amplicons, and absolute gene abundances were estimated with an internal standard (Thermus thermophilus genomes). Fecal coliforms were quantified by culture, and Vibrio vulnificus and V. parahaemolyticus with quantitative PCR. Fecal coliforms and V. vulnificus were detected in most samples, and a diverse assemblage of potential human pathogens were detected in all samples. These taxa followed two general patterns of abundance. Fecal coliforms and 16S rRNA genes for Enterobacteriaceae, Aeromonas, Arcobacter, Staphylococcus, and Bacteroides increased in abundance after a 1.3-inch rain event in May, and, for some taxa, after smaller rain events later in the season, suggesting that these are allochthonous organisms washed in from land. Clostridiaceae and Mycobacterium 16S rRNA gene abundances increased with day of the year and were not positively related to rainfall, suggesting that these are autochthonous organisms. Other groups followed both patterns, such as Legionella. Fecal coliform abundance did not correlate with most other taxa, but were extremely high following the large rainstorm in May when they co-occurred with a broad range of potential pathogen groups. V. vulnificus were absent during the large rainstorm, and did not correlate with 16S rRNA abundances of Vibrio spp. or most other taxa. These results highlight the complex nature of bacterial communities and the limited utility of using specific bacterial groups as indicators of pathogen presence.

Investigating monsoon and post-monsoon variabilities of bacterioplankton communities in a mangrove ecosystem

In mangrove environments, bacterioplankton communities constitute an important component of aquatic biota and play a major role in ecosystem processes. Variability of bacterioplankton communities from Sundarbans mangrove, located in the Indian subcontinent in South Asia and sits on the apex of Bay of Bengal, was investigated over monsoon and post-monsoon seasons. The study was undertaken in two stations in Sundarbans using 16S rRNA clone library and Illumina MiSeq approaches with focus on the functionally important members that participate in coastal biogeochemical cycling. Out of 544 sequenced clones, Proteobacteria dominated the study area (373 sequences) with persistence of two major classes, namely, Gammaproteobacteria and Alphaproteobacteria across both monsoon and post-monsoon seasons in both stations. Several sequences belonging to Sphingomonadales, Chromatiales, Alteromonadales, Oceanospirillales, and Bacteroidetes were encountered that are known to play important roles in coastal carbon cycling. Some sequences showed identity with published uncultured Planctomycetes and Chloroflexi highlighting their role in nitrogen cycling. The detection of two novel clades highlighted the existence of indigenous group of bacterioplankton that may play important roles in this ecosystem. The eubacterial V3-V4 region from environmental DNA extracted from the above two stations, followed by sequencing in Illumina MiSeq system, was also targeted in the study. A congruency between the clone library and Illumina approaches was observed. Strong variability in bacterioplankton community structure was encountered at a seasonal scale in link with precipitation. Drastic increase in sediment associated bacteria such as members of Firmicutes and Desulfovibrio was found in monsoon hinting possible resuspension of sediment-dwelling bacteria into the overlying water column. Principal component analysis (PCA) revealed dissolved ammonium and dissolved nitrate to account for maximum variation observed in the bacterioplankton community structure. Overall, the study showed that a strong interplay exists between environmental parameters and observed variability in bacterioplankton communities as a result of precipitation which can ultimately influence processes and rates linked to coastal biogeochemical cycles.

Projections of the future occurrence, distribution, and seasonality of three Vibrio species in the Chesapeake Bay under a high-emission climate change scenario

Illness caused by pathogenic strains of Vibrio bacteria incurs significant economic and health care costs in many areas around the world. In the Chesapeake Bay, the two most problematic species are V. vulnificus and V. parahaemolyticus, which cause infection both from exposure to contaminated water and consumption of contaminated seafood. We used existing Vibrio habitat models, four global climate models, and a recently developed statistical downscaling framework to project the spatiotemporal probability of occurrence of V. vulnificus and V. cholerae in the estuarine environment, and the mean concentration of V. parahaemolyticus in oysters in the Chesapeake Bay by the end of the 21st century. Results showed substantial future increases in season length and spatial habitat for V. vulnificus and V. parahaemolyticus, while projected increase in V. cholerae habitat was less marked and more spatially heterogeneous. Our findings underscore the need for spatially variable inputs into models of climate impacts on Vibrios in estuarine environments. Overall, economic costs associated with Vibrios in the Chesapeake Bay, such as incidence of illness and management measures on the shellfish industry, may increase under climate change, with implications for recreational and commercial uses of the ecosystem.

Effects of Desiccation Practices of Cultured Atlantic Oysters (Crassostrea virginica) on Vibrio spp. in Portersville Bay, Alabama, USA

The expansion of off-bottom aquaculture to the Gulf of Mexico has raised public health concerns for human health officials. High temperatures in the Gulf of Mexico are associated with high levels of Vibrio parahaemolyticus and Vibrio vulnificus. Routine desiccation practices associated with off-bottom aquaculture expose oysters to ambient air, allowing Vibrio spp. to proliferate in the closed oyster. Currently, there is limited research on the length of time needed for Vibrio spp. levels in desiccated oysters to return to background levels, defined as the levels found in oysters that remain continually submersed and not exposed to ambient air. This study determined the time needed to return V. parahaemolyticus, V. vulnificus, and Vibrio cholerae levels to background levels in oysters exposed to the following desiccation practices: 3-h freshwater dip followed by 24-h ambient air exposure, 27-h ambient air exposure, and control. All oysters were submerged at least 2 weeks prior to the beginning of each trial, with the control samples remaining submerged for the duration of each trial. Vibrio spp. levels were enumerated from samples collected on days 0, 1, 2, 3, 7, 10, and 14 after resubmersion using a three-tube most-probable-number enrichment followed by BAX PCR. V. cholerae levels were frequently (92%) below the limit of detection at all times, so they were not statistically analyzed. V. parahaemolyticus and V. vulnificus levels in the 27-h ambient air exposure and the 3-h freshwater dip followed by 24-h ambient air exposure samples were significantly elevated compared with background samples. In most cases, the Vibrio spp. levels in oysters in both desiccation treatments remained elevated compared with background levels until 2 or 3 days post-resubmersion. However, there was one trial in which the Vibrio spp. levels did not return to background levels until day 7. The results of this study provide scientific support that oyster farmers should be required to implement a minimum 7-day resubmersion regimen. This length of time allowed the Vibrio spp. levels to become not significantly different across all treatments.

Microbiomes of American Oysters (Crassostrea virginica) Harvested from Two Sites in the Chesapeake Bay

In this study, we used 16S rRNA gene amplicons to describe the bacterial microbiota associated with oysters (Crassostrea virginica) and seawater collected from two sites in the Chesapeake Bay. The dominant bacterial groups included those belonging to the order Pelagibacteraceae, family Enterobacteriaceae, and genus Synechococcus. The microbiomes varied among oysters from the same site and between the two sites and months.

Effects of varying concentrations of sodium chloride and acidic conditions on the behavior of Vibrio parahaemolyticus and Vibrio vulnificus cold-starved in artificial sea water microcosms

There has been limited information available on the behavior of Vibrio parahaemolyticus and Vibrio vulnificus as a function of higher levels of NaCl in combination with acidic pH. In the present study, bacterial suspensions were transferred into artificial seawater (pH 4-7) microcosms containing 0.75% NaCl and supplemented with 5, 10, and 30% NaCl, respectively. Each of V. parahaemolyticus and V. vulnificus was inoculated in these microcosms and fermented seafood, and then stored at 4 °C until the microbial populations reached below the detectable levels on agar plates (thiosulphate-citrate-bile salts-sucrose agar and tryptic soy agar amended with 3% NaCl). Consequently, V. parahaemolyticus ATCC 27969, V. parahaemolyticus ATCC 33844, and V. vulnificus ATCC 33815 rapidly reached the viable-but-nonculturable (VBNC) state with increasing levels (≤30%) of NaCl at 4 °C. Within seven days, these pathogens in seafood appeared to enter the VBNC state at 4 °C, as shown by the fluorescence microscopic assay.

Differences in Abundances of Total Vibrio spp., V. vulnificus, and V. parahaemolyticus in Clams and Oysters in North Carolina

Filter feeding shellfish can concentrate pathogenic bacteria, including Vibrio vulnificus and Vibrio parahaemolyticus, as much as 100-fold from the overlying water. These shellfish, especially clams and oysters, are often consumed raw, providing a route of entry for concentrated doses of pathogenic bacteria into the human body. The numbers of foodborne infections with these microbes are increasing, and a better understanding of the conditions that might trigger elevated concentrations of these bacteria in seafood is needed. In addition, if bacterial concentrations in water are correlated with those in shellfish, then sampling regimens could be simplified, as water samples can be more rapidly and easily obtained. After sampling of oysters and clams, either simultaneously or separately, for over 2 years, it was concluded that while Vibrio concentrations in oysters and water were related, this was not the case for levels in clams and water. When clams and oysters were collected simultaneously from the same site, the clams were found to have lower Vibrio levels than the oysters. Furthermore, the environmental parameters that were correlated with levels of Vibrio spp. in oysters and water were found to be quite different from those that were correlated with levels of Vibrio spp. in clams.

IMPORTANCE

This study shows that clams are a potential source of infection in North Carolina, especially for V. parahaemolyticus These findings also highlight the need for clam-specific environmental research to develop accurate Vibrio abundance models and to broaden the ecological understanding of clam-Vibrio interactions. This is especially relevant as foodborne Vibrio infections from clams are being reported.

Occurrence and distribution of bacteria indicators, chemical tracers and pathogenic vibrios in Singapore coastal waters

Water quality in Singapore's coastal area was evaluated with microbial indicators, pathogenic vibrios, chemical tracers and physico-chemical parameters. Sampling sites were grouped into two clusters (coastal sites at (i) northern and (ii) southern part of Singapore). The coastal sites located at northern part of Singapore along the Johor Straits exhibited greater pollution. Principal component analysis revealed that sampling sites at Johor Straits have greater loading on carbamazepine, while turbidity poses greater influence on sampling sites at Singapore Straits. Detection of pathogenic vibrios was also more prominent at Johor Straits than the Singapore Straits. This study examined the spatial variations in Singapore's coastal water quality and provided the baseline information for health risk assessment and future pollution management.

The contribution of marine aggregate-associated bacteria to the accumulation of pathogenic bacteria in oysters: an agent-based model

Bivalves process large volumes of water, leading to their accumulation of bacteria, including potential human pathogens (e.g., vibrios). These bacteria are captured at low efficiencies when freely suspended in the water column, but they also attach to marine aggregates, which are captured with near 100% efficiency. For this reason, and because they are often enriched with heterotrophic bacteria, marine aggregates have been hypothesized to function as important transporters of bacteria into bivalves. The relative contribution of aggregates and unattached bacteria to the accumulation of these cells, however, is unknown. We developed an agent‐based model to simulate accumulation of vibrio‐type bacteria in oysters. Simulations were conducted over a realistic range of concentrations of bacteria and aggregates and incorporated the dependence of pseudofeces production on particulate matter. The model shows that the contribution of aggregate‐attached bacteria depends strongly on the unattached bacteria, which form the colonization pool for aggregates and are directly captured by the simulated oysters. The concentration of aggregates is also important, but its effect depends on the concentration of unattached bacteria. At high bacterial concentrations, aggregates contribute the majority of bacteria in the oysters. At low concentrations of unattached bacteria, aggregates have a neutral or even a slightly negative effect on bacterial accumulation. These results provide the first evidence suggesting that the concentration of aggregates could influence uptake of pathogenic bacteria in bivalves and show that the tendency of a bacterial species to remain attached to aggregates is a key factor for understanding species‐specific accumulation.

Vibrio bacteria in raw oysters: managing risks to human health

The human-pathogenic marine bacteria Vibrio vulnificus and V. parahaemolyticus are strongly correlated with water temperature, with concentrations increasing as waters warm seasonally. Both of these bacteria can be concentrated in filter-feeding shellfish, especially oysters. Because oysters are often consumed raw, this exposes people to large doses of potentially harmful bacteria. Various models are used to predict the abundance of these bacteria in oysters, which guide shellfish harvest policy meant to reduce human health risk. Vibrio abundance and behaviour varies from site to site, suggesting that location-specific studies are needed to establish targeted risk reduction strategies. Moreover, virulence potential, rather than simple abundance, should be also be included in future modeling efforts.

Antibiotic resistance and plasmid profiling of Vibrio spp. in tropical waters of Peninsular Malaysia

Vibrio species isolated from four different sampling stations in the west coast of Peninsular Malaysia were screened for their antimicrobial resistance and plasmid profiles. A total of 138 isolates belonging to 15 different species were identified. Vibrio campbellii, V. parahaemolyticus, V. harveyi, and V. tubiashii were found to predominance species at all stations. High incidence of erythromycin, ampicillin, and mecillinam resistance was observed among the Vibrio isolates. In contrast, resistance against aztreonam, cefepime, streptomycin, sulfamethoxazole, and sulfonamides was low. All the Vibrio isolates in this study were found to be susceptible to imipenem, norfloxacin, ofloxacin, chloramphenicol, trimethoprim/sulfamethoxazole, and oxytetracycline. Ninety-five percent of the Vibrio isolates were resistant to one or more different classes of antibiotic, and 20 different resistance antibiograms were identified. Thirty-two distinct plasmid profiles with molecular weight ranging from 2.2 to 24.8 kb were detected among the resistance isolates. This study showed that multidrug-resistant Vibrio spp. were common in the aquatic environments of west coast of Peninsular Malaysia.

Successful Treatment of a Case of Necrotizing Fasciitis due to Vibrio vulnificus in a Cold Climate in Japan

Vibrio vulnificus infection often occurs in warm regions, frequently leading to necrotizing fasciitis, sepsis, and death. We herein report a rare case presenting in a cold climate region in northern Japan, Aomori district, of a V. vulnificus infection complicated by necrotizing fasciitis and septic shock. The patient's prior history of injury and typical clinical course were helpful clues to the diagnosis of V. vulnificus infection, and early initiation of antimicrobial treatment saved his life. V. vulnificus infection should be considered even in cold regions, particularly if patients have risk factors.

Microbiological Quality of Seafood Marketed in Taiwan

Seafood is often associated with foodborne illnesses, and Vibrio parahaemolyticus is the most common pathogen implicated in outbreaks in Taiwan. In this study, the microbiological quality of 300 raw or mixed ready-to-eat (RTE) and other cooking-needed seafood samples was examined. The total aerobic and coliform counts of the RTE samples were significantly higher than those of other cooking-needed samples. On average, 55.8 and 29.7% of the RTE samples failed to meet the local microbiological standards for total aerobic (5 log CFU/g) and coliform (3 log most probable number [MPN] per g), counts respectively; the corresponding percentages for the RTE samples from Taipei City were 9.1 and 18.2%, respectively. The total aerobic and coliform counts in the RTE samples from supermarkets and chain restaurants were significantly lower than those from traditional restaurants. The Vibrio species were more frequently identified in the cooking-needed samples than in RTE samples. Low incidences of V. parahaemolyticus (1.4%), V. vulnificus (1.9%), and V. cholerae (0%) were detected in most RTE samples. High densities of V. parahaemolyticus and V. vulnificus (1,200 MPN/g) were detected in a few RTE samples, only one of which contained toxigenic (tdh(+)) V. parahaemolyticus. The results of this investigation reveal that better hygiene of seafood providers such as chain restaurants, supermarkets, and traditional restaurants in Taipei City would effectively improve the microbiological quality of the seafood. The results will facilitate the establishment of measures for controlling the risks associated with seafood in Taiwan.

Clinical and environmental genotypes of Vibrio vulnificus display distinct, quorum-sensing-mediated, chitin detachment dynamics

The ability for bacteria to attach to and detach from various substrata is important for colonization, survival and transitioning to new environments. An opportunistic human pathogen, Vibrio vulnificus, can cause potentially fatal septicemia after ingestion of undercooked seafood. Based on genetic polymorphisms, strains of this species are subtyped into clinical (C) and environmental (E) genotypes. Vibrio vulnificus readily associates with chitin, thus we investigated chitin detachment dynamics in these disparate genotypes. We found that C-genotypes detach significantly more than E-genotypes after 24 hours in aerobic as well as anaerobic conditions. Furthermore, expression of genes involved in type IV pilin production was significantly downregulated in C-genotypes compared to E-genotypes, suggesting an importance in detachment. Interestingly, gbpA, a gene that has been shown to be important in host colonization in V. cholerae, was upregulated in the C-genotypes during detachment. Additionally, we found that C-genotypes detached to a greater extent, and produced more quorum-sensing (QS) autoinducer-2 molecules relative to E-genotypes, which suggests a role for QS in detachment. These findings suggest that for V. vulnificus, QS-mediated detachment may be a potential mechanism for transitioning into a human host for C-genotypes, while facilitating E-genotype maintenance in the estuarine environment.

Rapid proliferation of Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae during freshwater flash floods in French Mediterranean coastal lagoons

Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae of 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 of V. parahaemolyticus, V. vulnificus, and V. cholerae varied from 0 to 1.5 × 10(3) most probable number (MPN)/liter, 0.7 to 2.1 × 10(3) MPN/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 in Vibrio concentration to ca. 10(4) MPN/liter. The highest concentrations were reached with salinities between 10 and 20‰ for V. parahaemolyticus, 10 and 15‰ for V. vulnificus, and 5 and 12‰ for V. cholerae. Thus, an abrupt decrease in salinity caused by heavy rainfall and major flooding favored growth of human-pathogenic Vibrio spp. 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 these Vibrio spp. in shellfish-harvesting areas of the lagoons.

Influence of Environmental Factors on Vibrio spp. in Coastal Ecosystems

Various studies have examined the relationships between vibrios and the environmental conditions surrounding them. However, very few reviews have compiled these studies into cohesive points. This may be due to the fact that these studies examine different environmental parameters, use different sampling, detection, and enumeration methodologies, and occur in diverse geographic locations. The current article is one approach to compile these studies into a cohesive work that assesses the importance of environmental determinants on the abundance of vibrios in coastal ecosystems.

Development of a matrix tool for the prediction of Vibrio species in oysters harvested from North Carolina

The United States has federal regulations in place to reduce the risk of seafood-related infection caused by the estuarine bacteria Vibrio vulnificus and Vibrio parahaemolyticus. However, data to support the development of regulations have been generated in a very few specific regions of the nation. More regionally specific data are needed to further understand the dynamics of human infection relating to shellfish-harvesting conditions in other areas. In this study, oysters and water were collected from four oyster harvest sites in North Carolina over an 11-month period. Samples were analyzed for the abundances of total Vibrio spp., V. vulnificus, and V. parahaemolyticus; environmental parameters, including salinity, water temperature, wind velocity, and precipitation, were also measured simultaneously. By utilizing these data, preliminary predictive management tools for estimating the abundance of V. vulnificus bacteria in shellfish were developed. This work highlights the need for further research to elucidate the full suite of factors that drive V. parahaemolyticus abundance.

Abundance of Vibrio cholerae, V. vulnificus, and V. parahaemolyticus in oysters (Crassostrea virginica) and clams (Mercenaria mercenaria) from Long Island sound

Vibriosis is a leading cause of seafood-associated morbidity and mortality in the United States. Typically associated with consumption of raw or undercooked oysters, vibriosis associated with clam consumption is increasingly being reported. However, little is known about the prevalence of Vibrio spp. in clams. The objective of this study was to compare the levels of Vibrio cholerae, Vibrio vulnificus, and Vibrio parahaemolyticus in oysters and clams harvested concurrently from Long Island Sound (LIS). Most probable number (MPN)-real-time PCR methods were used for enumeration of total V. cholerae, V. vulnificus, V. parahaemolyticus, and pathogenic (tdh(+) and/or trh(+)) V. parahaemolyticus. V. cholerae was detected in 8.8% and 3.3% of oyster (n = 68) and clam (n = 30) samples, with levels up to 1.48 and 0.48 log MPN/g in oysters and clams, respectively. V. vulnificus was detected in 97% and 90% of oyster and clam samples, with median levels of 0.97 and -0.08 log MPN/g, respectively. V. parahaemolyticus was detected in all samples, with median levels of 1.88 and 1.07 log MPN/g for oysters and clams, respectively. The differences between V. vulnificus and total and pathogenic V. parahaemolyticus levels in the two shellfish species were statistically significant (P < 0.001). These data indicate that V. vulnificus and total and pathogenic V. parahaemolyticus are more prevalent and are present at higher levels in oysters than in hard clams. Additionally, the data suggest differences in vibrio populations between shellfish harvested from different growing area waters within LIS. These results can be used to evaluate and refine illness mitigation strategies employed by risk managers and shellfish control authorities.

Role of anaerobiosis in capsule production and biofilm formation in Vibrio vulnificus

Vibrio vulnificus, a pervasive human pathogen, can cause potentially fatal septicemia after consumption of undercooked seafood. Biotype 1 strains of V. vulnificus are most commonly associated with human infection and are separated into two genotypes, clinical (C) and environmental (E), based on the virulence-correlated gene. For ingestion-based vibriosis to occur, this bacterium must be able to withstand multiple conditions as it traverses the gastrointestinal tract and ultimately gains entry into the bloodstream. One such condition, anoxia, has yet to be extensively researched in V. vulnificus. We investigated the effect of oxygen availability on capsular polysaccharide (CPS) production and biofilm formation in this bacterium, both of which are thought to be important for disease progression. We found that lack of oxygen elicits a reduction in both CPS and biofilm formation in both genotypes. This is further supported by the finding that pilA, pilD, and mshA genes, all of which encode type IV pilin proteins that aid in attachment to surfaces, were downregulated during anaerobiosis. Surprisingly, E-genotypes exhibited distinct differences in gene expression levels of capsule and attachment genes compared to C-genotypes, both aerobically and anaerobically. The importance of understanding these disparities may give insight into the observed differences in environmental occurrence and virulence potential between these two genotypes of V. vulnificus.