Occurrence, seasonality and genetic diversity of Vibrio vulnificus in coastal seaweeds and water along the Kii Channel, Japan

Isolation of Vibrio cholerae and Vibrio vulnificus from Estuarine Waters, and Genotyping of V. vulnificus Isolates Using Loop-Mediated Isothermal Amplification

Bacteria in the genus Vibrio are ubiquitous in estuarine and coastal waters. Some species (including Vibrio cholerae and Vibrio vulnificus) are known human pathogens causing ailments like cholera, diarrhea, or septicemia. Notably, V. vulnificus can also cause a severe systemic infection (known as vibriosis) in eels raised in aquaculture facilities. Water samples were periodically collected from the estuary of the Asahi River, located in the southern part of Okayama City, Japan. These samples were directly plated onto CHROMagar Vibrio plates, and colonies displaying turquoise-blue coloration were selected. Thereafter, polymerase chain reaction was used to identify V. cholerae and V. vulnificus. A total of 30 V. cholerae strains and 194 V. vulnificus strains were isolated during the warm season when the water temperature (WT) was higher than 20 °C. Concurrently, an increase in coliforms was observed during this period. Notably, V. vulnificus has two genotypes, designated as genotype 1 and genotype 2. Genotype 1 is pathogenic to humans, while genotype 2 is pathogenic to both humans and eels. The loop-mediated isothermal amplification method was developed to rapidly determine genotypes at a low cost. Of the 194 strains isolated, 80 (41.2%) were identified as genotype 1 strains. Among the 41 strains isolated when the WTs were higher than 28 °C, 25 strains (61.0%) belonged to genotype 1. In contrast, of the 32 strains isolated when the WTs were lower than 24 °C, 27 strains (84.4%) belonged to genotype 2. These results suggest that the distribution of the two genotypes was influenced by WT.

Macrophytes and their wrack as a habitat for faecal indicator bacteria and Vibrio in coastal marine environments

Waterborne pathogenic bacteria, including faecal indicator bacteria and potentially pathogenic Vibrio, are a global concern for diseases transmitted through water. A systematic review was conducted to analyse publications that investigated these bacteria in relation to macrophytes (seagrasses and macroalgae) in coastal marine environments. The highest quantities of FIB were found on brown algae and seagrasses, and the highest quantities of Vibrio bacteria were on red algae. The most extensively studied macrophyte group was brown algae, green algae were the least researched. Macrophyte wrack was found to favor the presence of FIB, but there is a lack of information about Vibrio quantities in this environment. To understand the role of Vibrio bacteria that are pathogenic to humans, molecular methods complementary to cultivation methods should be used. Further research is needed to understand the underlying mechanisms of FIB and potentially pathogenic Vibrio with macrophytes and their microbiome in the coastal marine environment.

Survival of Inoculated Vibrio spp., Shigatoxigenic Escherichia coli, Listeria monocytogenes, and Salmonella spp. on Seaweed (Sugar Kelp) During Storage

Bacteria including Vibrio spp. persist in coastal waters and can contaminate edible seaweeds. Pathogens such as Listeria monocytogenes, shigatoxigenic Escherichia coli (STEC), and Salmonella have been associated with and present serious health risks in minimally processed vegetables including seaweeds. This study evaluated the survival of four pathogens inoculated onto two product forms of sugar kelp subjected to different storage temperatures. The inoculation comprised of a cocktail of two Listeria monocytogenes and STEC strains, two Salmonella serovars, and two Vibrio species. STEC and Vibrio were grown and applied in salt-containing media to simulate preharvest contamination, whereas L. monocytogenes and Salmonella inocula were prepared to simulate postharvest contamination. Samples were stored at 4°C and 10°C for 7 days, and 22°C for 8 h. Microbiological analyses were performed periodically (1, 4, 8, 24 h, etc.) to evaluate the effects of storage temperature on pathogen survival. Pathogen populations decreased under all storage conditions, but survival was greatest for all species at 22°C, with STEC exhibiting significantly less reduction (1.8 log CFU/g) than Salmonella, L. monocytogenes, and Vibrio (3.1, 2.7, and 2.7 log CFU/g, respectively) after storage. The largest population reduction (5.3 log CFU/g) was observed in Vibrio stored at 4°C for 7 days. Regardless of storage temperature, all pathogens remained detectable at the end of the study duration. Results emphasize the need for strict adherence to temperature control for kelp as temperature abuse may support pathogen survival, especially STEC, during storage, and the need for prevention of postharvest contamination, particularly with Salmonella.

Characterization of ready-to-eat fish surface as a potential source of contamination of Vibrio parahaemolyticus biofilms

The worldwide consumption of ready-to-eat seafood products has steadily increased due to a range of health benefits. However, depending on the handling or cutting process of raw fish, ready-to-eat sashimi can be exposed to microbiological risks that can lead to foodborne infection by marine pathogens. Since surface characteristics are key factors for microbial adhesion and biofilm formation, the present study aims to determine the correlation between raw fish skin properties and Vibrio parahaemolyticus biofilm formation. We analyzed V. parahaemolyticus biofilms (ATCC 17802; initially inoculated ca. 2 or 4 log CFU/cm²) on fish skin (gizzard shad, pomfret, red snapper, and mackerel; fish species served as sashimi without peeling the skin) formed under simulated marine environments (incubating in artificial seawater with rocking motion at 30 °C, the maximum temperature of seasonal seawater) for 24 h. The characteristics of fish skin were determined using confocal laser scanning microscopy/scanning electron microscopy. V. parahaemolyticus showed higher biofilm counts on fish skins than on stainless steel, which was used as a control (P < 0.05). In particular, V. parahaemolyticus formed biofilms with significantly higher levels of bacterial populations on gizzard shad and pomfret (ca. 5 log CFU/cm²; P < 0.05), highlighting the relationship between the biofilm formation level and the characteristics of gizzard shad and pomfret skins. The surface roughness of fish skins, including the main roughness parameters (Ra, Rq, and Rz), influenced the attachment of V. parahaemolyticus (P < 0.05). Additionally, images of V. parahaemolyticus biofilms suggested that different topographical profiles of fish species (e.g., mucus, unique structural features, etc.) could cause V. parahaemolyticus to exhibit different biofilm phenotypes, such as sticking to or entangling on the fish skin surface. The major findings of this study provide various phenotypic adhesions of V. parahaemolyticus to fish skin in considerations of the potential hazard for the consumption of ready-to-eat sashimi served with its skin.

Environmental Reservoirs of Pathogenic Vibrio spp. and Their Role in Disease: The List Keeps Expanding

Vibrio species are natural inhabitants of aquatic environments and have complex interactions with the environment that drive the evolution of traits contributing to their survival. These traits may also contribute to their ability to invade or colonize animal and human hosts. In this review, we attempt to summarize the relationships of Vibrio spp. with other organisms in the aquatic environment and discuss how these interactions could potentially impact colonization of animal and human hosts.

Inhibitory Effects of Polymyxin B and Human LL-37 on the Flagellin Expression in Vibrio vulnificus

Vibrio vulnificus, an opportunistic human pathogen responsible for primary septicemia, initiates pathogenesis by attachment to the intestinal epithelial cells for which the motility by the polar flagellum plays an essential role. The proteomic analysis of outer membrane proteins showed that the treatment with the 1/2 minimum inhibitory concentration (MIC) of polymyxin B (a bacterial antimicrobial peptide) led to the reduced production of flagellin (a major component of the polar flagellum). Furthermore, the bacterial motility was inhibited in the presence of 1/2 MIC of polymyxin B. V. vulnificus has six flagellin genes organized into the flaFBA and flaCDE loci. The flaA was found to be expressed higher than flaC, and its expression was significantly decreased by polymyxin B. As well as polymyxin B, the 1/2 MIC of LL-37 (a human intestinal antimicrobial peptide) reduced the expression of flaA. In addition, among four fragments of LL-37, KI-18 and FK-13 containing F¹⁷KRIVQRIKDELR²⁹ could lead to the decreased expression of flaA. Because the motility closely relates to virulence of V. vulnificus, the findings obtained herein indicate that LL-37 may reduce the bacterial virulence through inhibition of the motility via the polar flagellum.

Microbiological Food Safety of Seaweeds

The use of seaweeds in the human diet has a long history in Asia and has now been increasing also in the western world. Concurrent with this trend, there is a corresponding increase in cultivation and harvesting for commercial production. Edible seaweed is a heterogenous product category including species within the green, red, and brown macroalgae. Moreover, the species are utilized on their own or in combinatorial food products, eaten fresh or processed by a variety of technologies. The present review summarizes available literature with respect to microbiological food safety and quality of seaweed food products, including processing and other factors controlling these parameters, and emerging trends to improve on the safety, utilization, quality, and storability of seaweeds. The over- or misuse of antimicrobials and the concurrent development of antimicrobial resistance (AMR) in bacteria is a current worldwide health concern. The role of seaweeds in the development of AMR and the spread of antimicrobial resistance genes is an underexplored field of research and is discussed in that context. Legislation and guidelines relevant to edible seaweed are also discussed.

Dynamics, Diversity, and Virulence of Aeromonas spp. in Homestead Pond Water in Coastal Bangladesh

Aeromonads are aquatic bacteria associated with frequent outbreaks of diarrhea in coastal Bangladesh, but their potential risks from environmental sources have remained largely unexplored. This study, over 2 years, examined homestead pond waters in the region for monthly dynamics and diversity of Aeromonas spp. The bacterial counts showed bi-modal annual growth peak, pre- and post-monsoon, strongly correlating (p < 0.0005) with temperature. Of 200 isolates characterized, Aeromonas veronii bv. sobria (27%) was predominant among co-existent Aeromonas schubertii (20%), Aeromonas hydrophila (17%), Aeromonas caviae (13%), and three more. PCR screening of virulence-related genes identified 15 genotypes (I to XV), however, enterotoxigenicity in animal model was observed for five genotypes, ca. 18% (nine of 50) strains, prevalent in A. veronii bv. sobria, A. hydrophila, and A. caviae. Pathogenic strains were distinguishable by possessing at least three of the major virulence genes: ascV, hlyA, ela, ast, and alt, together with accessory virulence factors. PFGE of XbaI-digested genomic DNA revealed high genetic diversity and distant lineage of potentially toxigenic clones. Therefore, along with increased global warming, Aeromonas spp. having multi-factorial virulence potential in coastal ponds that serve as drinking water sources pose a potential health risk, and underscores the need for routine monitoring.

Effect of Seawater Temperature Increase on the Occurrence of Coastal Vibrio vulnificus Cases: Korean National Surveillance Data from 2003 to 2016

The purpose of this study was to assess the association between seawater temperature and Vibrio vulnificus cases in coastal regions of Korea. All V. vulnificus cases in coastal regions notified to the Korea Disease Control and Prevention Agency between 2003 and 2016 were included in this work. Data for seawater temperature on the south, west, and east coast during the study period were provided by the Korea Oceanographic Data Center of the National Institute of Fisheries Science. We used a generalized additive model and performed a negative binomial regression analysis. In total, 383 notified cases were analyzed (west coast: 196 cases, south coast: 162, and east coast: 25). The maximum seawater temperature was the most significant predictor of V. vulnificus cases on the south and east coasts (relative risk according to the 1 °C increase in seawater temperature (RR) = 1.35 (95% confidence interval (CI): 1.19–1.53) and 1.30 (95% CI: 1.06–1.59), respectively). However, the mean seawater temperature was the most significant predictor for the west coast (RR = 1.34 (95% CI: 1.20–1.51)). These results indicate that continuously monitoring seawater temperature increase in each coastal area is crucial to prevent V. vulnificus infections and protect high-risk groups, such as persons with liver disease.

The microbial safety of seaweed as a feed component for black soldier fly (Hermetia illucens) larvae

Farmed insects can offer an environmentally sustainable aquafeed or livestock feed ingredient. The value of black soldier fly (Hermetia illucens) (BSF) larvae could be improved by enrichment in omega-3 through the dietary inclusion of seaweed. However, the industry practice of drying seaweed at low temperatures to retain nutritional properties may benefit the survival of human pathogenic bacteria, particularly if the seaweed has been harvested from contaminated water. Here we have demonstrated that E. coli and E. coli O157:H7 died-off in seaweed dried at 50 °C, although both were detected in the dried powder following 72 h storage. V. parahaemolyticus fell below the level of detection in stored seaweed after drying at ≥ 50 °C, but L. monocytogenes remained detectable, and continued to grow in seaweed dried at ≤60 °C. Therefore, drying seaweed at low temperatures risks pathogen carry-over into insects destined for animal feed. BSF larvae reared on an artificially contaminated seaweed-supplemented diet also became contaminated by all four bacteria present in the supplement. Water quality at seaweed harvesting sites, seaweed desiccation, and insect rearing practices, represent critical points where development of regulatory standards could achieve targeted control of pathogenic hazards.

Salinity and Time Can Alter Epibacterial Communities of an Invasive Seaweed

The establishment of epibacterial communities is fundamental to seaweed health and fitness, in modulating ecological interactions and may also facilitate adaptation to new environments. Abiotic factors like salinity can determine bacterial abundance, growth and community composition. However, influence of salinity as a driver of epibacterial community composition (until species level) has not been investigated for seaweeds and especially under long time scales. We also do not know how abiotic stressors may influence the 'core' bacterial species of seaweeds. Following an initial (immediately after field collection) sampling of epibacterial community of an invasive red seaweed Agarophyton vermicullophylum, we conducted a long term mesocosm experiment for 5 months, to examine the influence of three different salinities (low, medium and high) at two different time points (3 months after start of experiment and 5 months, i.e., at the end of experiment) on the epibacterial community richness and composition of Agarophyton. Metagenomic sequencing showed that epibacterial communities changed significantly according to salinity and time points sampled. Epibacterial richness was significantly different between low and high salinities at both time points. Epibacterial richness also varied significantly between 3 months (after start of experiment) and 5 months (end of experiment) within low, medium and high salinity level. Irrespective of salinity levels and time points sampled 727 taxa consistently appeared in all Agarophyton samples hinting at the presence of core bacterial species on the surface of the alga. Our results indicate that both salinity and time can be major driving forces in structuring epibacterial communities of seaweeds with respect to richness and β-diversity. We highlight the necessity of conducting long term experiments allowing us to detect and understand epibacterial succession over time on seaweeds.

Biomonitoring of the environmental indicator and pathogenic microorganisms assortment in foremost pilgrimage beaches of the Bay of Bengal, Southeast coast, India

The present study is aimed to monitoring the ecological indicator and pathogenic microorganism diversity in pilgrimage places beach sand on the Bay of Bengal coast. The samples were collected from three locations and four different sites, and were analyzed by following standard methods. The results clearly indicates, ritual activities were highly contaminated in the beach sand qualities, and exceeded with the standard permissible limit of WHO, USEPA, EU, CPCB beach sand recreational and other contacts activities including pH (11%), TBC (100%), TCB (97%), FCB (88%), TEB (75%), E. coli (75%), disease-causing possible level of Klebsiella (84%), Shigella (75%), Salmonella (63%) and Vibrio (56%). The statistical tools were applied to find the strong evidence. The current study pointed out the major effects on the diffusion of potentially pathogenic microorganisms along the shoreline provided useful information for the setup of measures for public health protection in the Bay of Bengal coast.

Identification of Asparagopsis armata-associated bacteria and characterization of their bioactive potential

Macroalgae‐associated bacteria have already proved to be an interesting source of compounds with therapeutic potential. Accordingly, the main aim of this study was to characterize Asparagopsis armata‐associated bacteria community and evaluate their capacity to produce substances with antitumor and antimicrobial potential. Bacteria were selected according to their phenotype and isolated by the streak plate technique. The identification was carried out by the RNA ribosomal 16s gene amplification through PCR techniques. The antimicrobial activities were evaluated against seven microorganisms (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae, Candida albicans) by following their growth through spectrophotometric readings. Antitumor activities were evaluated in vitro on human cell lines derived from hepatocellular (HepG‐2) and breast carcinoma (MCF‐7) using the MTT method. The present work identified a total of 21 bacteria belonging to the genus Vibrio, Staphylococcus, Shewanella, Alteromonadaceae, Bacillus, Cobetia, and Photobacterium, with Vibrio being the most abundant (42.86%). The extract of Shewanella sp. ASP 26 bacterial strain induced the highest antimicrobial activity, namely against Bacillus subtilis and Staphylococcus aureus with an IC₅₀ of 151.1 and 346.8 μg/mL, respectively. These bacteria (Shewanella sp.) were also the ones with highest antitumor potential, demonstrating antiproliferative activity on HepG‐2 cells. Asparagopsis armata‐associated bacteria revealed to be a potential source of compounds with antitumor and antibacterial activity.

Environmental and hydroclimatic factors influencing Vibrio populations in the estuarine zone of the Bengal delta

The objective of this study was to determine environmental parameters driving Vibrio populations in the estuarine zone of the Bengal delta. Spatio-temporal data were collected at river estuary, mangrove, beach, pond, and canal sites. Effects of salinity, tidal amplitude, and a cyclone and tsunami were included in the study. Vibrio population shifts were found to be correlated with tide-driven salinity and suspended particulate matter (SPM). Increased abundance of Vibrio spp. in surface water was observed after a cyclone, attributed to re-suspension of benthic particulate organic carbon (POC), and increased availability of chitin and dissolved organic carbon (DOC). Approximately a two log₁₀ increase in the (p < 0.05) number of Vibrio spp. was observed in < 20 μm particulates, compared with microphytoplankton (20-60 μm) and zooplankton > 60 μm fractions. Benthic and suspended sediment comprised a major reservoir of Vibrio spp. Results of microcosm experiments showed enhanced growth of vibrios was related to concentration of organic matter in SPM. It is concluded that SPM, POC, chitin, and salinity significantly influence abundance and distribution of vibrios in the Bengal delta estuarine zone.

Early clinical manifestations of vibrio necrotising fasciitis

We present five patients with vibrio necrotising fasciitis, a lethal and disabling disease. Two of these patients had a history of exposure to either warm seawater or raw/live seafood, three had underlying chronic liver disease, and four presented with hypotension and fever. There were three deaths and four patients required intensive care unit stays. Among the two survivors, one had high morbidity. Only one patient met the criteria of Laboratory Risk Indicator for Necrotising Fasciitis score > 6. A clinician should suspect possible vibrio necrotising fasciitis if the following are present: contact with fresh seafood/warm seawater, a known history of chronic liver disease and pain that is out of proportion to cutaneous signs. All patients must be managed via intensive care in high dependency units. We recommend a two-step surgical protocol for patient management involving an initial local debridement, followed by a second-stage radical debridement and skin grafting.

First Multi-Year Retrospective Study on Vibrio Parhaemolyticus and Vibrio Vulnificus Prevalence in Ruditapes Philippinarum Harvested in Sacca Di Goro, Italy

The present work describes a retrospective study aiming to verify a possible correlation between the environmental conditions (temperature, salinity and dissolved oxygen), the abundance of Vibrio spp., and the prevalence of V. parahaemolyticus and V. vulnificus in the Manila clam R. philippinarum harvested in Sacca di Goro, Emilia-Romagna Region, Northern Italy. On the whole, 104 samples, collected in the period 2007-2015 and submitted to microbiological analyses (isolation and genotyping), have been reconsidered for Vibrio spp. load, V. parahaemolyticus prevalence (total, gene marker toxRP; potentially pathogenic, gene markers tdh and/or trh) and V. vulnificus prevalence (total, gene markers vvhA and hsp) together with environmental data obtained from the monitoring activity of the Emilia-Romagna Regional Agency for the Prevention, the Environment and the Energy. Environmental data have been processed to calculate the median of each, assessing the seasonal range of seawater temperature (warmer months: April-October, T°C >16.45°C; cooler months November-March, T°C <16.45°C), salinity (<or>27 psu), and dissolved oxygen (< or >8.2 mg/L). Total V. vulnificus, total and potentially pathogenic V. parahaemolyticus were present respectively in the 11.5, 29.8 and 6.7% of the samples. The Vibrio spp. load (mean value of 4.69±0.65 log₁₀ colony forming unit g^-1) and the prevalence of potentially pathogenic V. parahaemolyticus, were not significantly correlated to the environmental conditions (P>0.05), whereas the prevalence of both total V. vulnificus and total V. parahaemolyticus was significantly higher in the warmer period (P<0.05), without correlation with salinity and dissolved oxygen values (P>0.05).

Detection and Quantification of Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus in Coastal Waters of Guinea-Bissau (West Africa)

V. cholerae, V. parahaemolyticus, and V. vulnificus are recognized human pathogens. Although several studies are available worldwide, both on environmental and clinical contexts, little is known about the ecology of these vibrios in African coastal waters. In this study, their co-occurrence and relationships to key environmental constraints in the coastal waters of Guinea-Bissau were examined using the most probable number-polymerase chain reaction (MPN-PCR) approach. All Vibrio species were universally detected showing higher concentrations by the end of the wet season. The abundance of V. cholerae (ISR 16S-23S rRNA) ranged 0-1.2 × 10(4) MPN/L, whereas V. parahaemolyticus (toxR) varied from 47.9 to 1.2 × 10(5) MPN/L. Although the presence of genotypes associated with virulence was found in environmental V. cholerae isolates, ctxA+ V. cholerae was detected, by MPN-PCR, only on two occasions. Enteropathogenic (tdh+ and trh+) V. parahaemolyticus were detected at concentrations up to 1.2 × 10(3) MPN/L. V. vulnificus (vvhA) was detected simultaneously in all surveyed sites only at the end of the wet season, with maximum concentrations of 1.2 × 10(5) MPN/L. Our results suggest that sea surface water temperature and salinity were the major environmental controls to all Vibrio species. This study represents the first detection and quantification of co-occurring Vibrio species in West African coastal waters, highlighting the potential health risk associated with the persistence of human pathogenic Vibrio species.

Distribution of Fatal Vibrio Vulnificus Necrotizing Skin and Soft-Tissue Infections: A Systematic Review and Meta-Analysis

Vibrio vulnificus necrotizing skin and soft tissue infections (VNSSTIs), which have increased significantly over the past few decades, are still highly lethal and disabling diseases despite advancing antibiotic and infection control practices. We, therefore, examined the spatiotemporal distribution of worldwide reported episodes and associated mortality rates of VNSSTIs between 1966 and 2014. The PubMed and Cochrane Library databases were systematically searched for observational studies on patients with VNSSTIs. The primary outcome was all-cause mortality. We did random-effects meta-analysis to obtain estimates for primary outcomes; the estimates are presented as means plus a 95% confidence interval (CI). Data from the selected studies were also extracted and pooled for correlation analyses.Nineteen studies of 2227 total patients with VNSSTIs were analyzed. More than 95% of the episodes occurred in the subtropical western Pacific and Atlantic coastal regions of the northern hemisphere. While the number of cases and the number of deaths were not correlated with the study period (rs = 0.476 and 0.310, P = 0.233 and 0.456, respectively), the 5-year mortality rate was significantly negatively correlated with them (rs = -0.905, P = 0.002). Even so, the pooled estimate of total mortality rates from the random-effects meta-analysis was as high as 37.2% (95% CI: 0.265-0.479).These data suggest that VNSSTIs are always an important public health problem and will become more critical and urgent because of global warming. Knowing the current distribution of VNSSTIs will help focus education, policy measures, early clinical diagnosis, and appropriate medical and surgical treatment for them.

Resolving conflicts in public health protection and ecosystem service provision at designated bathing waters

Understanding and quantifying the trade-off between the requirement for clean safe bathing water and beaches and their wider ecosystem services is central to the aims of the European Union (EU) Marine Strategy Framework Directive (MSFD), and vital for the sustainability and economic viability of designated bathing waters. Uncertainty surrounding the impacts of ensuing bathing water policy transitions, e.g. the EU revised Bathing Waters Directive (rBWD), puts new urgency on our need to understand the importance of natural beach assets for human recreation, wildlife habitat and for protection from flooding and erosion. However, managing coastal zones solely in terms of public health could have potentially negative consequences on a range of other social and cultural ecosystem services, e.g. recreation. Improving our knowledge of how bathing waters, surrounding beach environments and local economies might respond to shifts in management decisions is critical in order to inform reliable decision-making, and to evaluate future implications for human health. In this paper we explore the conflicts and trade-offs that emerge at public beach environments, and propose the development of an evaluative framework of viable alternatives in environmental management whereby bathing waters are managed for their greatest utility, driven by identifying the optimal ecosystem service provision at any particular site.

Sediment and vegetation as reservoirs of Vibrio vulnificus in the Tampa Bay Estuary and Gulf of Mexico

The opportunistic pathogen Vibrio vulnificus occurs naturally in estuarine habitats and is readily cultured from water and oysters under warm conditions but infrequently at ambient conditions of <15°C. The presence of V. vulnificus in other habitats, such as sediments and aquatic vegetation, has been explored much less frequently. This study investigated the ecology of V. vulnificus in water by culture and quantitative PCR (qPCR) and in sediment, oysters, and aquatic vegetation by culture. V. vulnificus samples were taken from five sites around Tampa Bay, FL. Levels determined by qPCR and culture were significantly correlated (P = 0.0006; r = 0.352); however, V. vulnificus was detected significantly more frequently by qPCR (85% of all samples) compared to culture (43%). Culturable V. vulnificus bacteria were recovered most frequently from oyster samples (70%), followed by vegetation and sediment (∼50%) and water (43%). Water temperature, which ranged from 18.5 to 33.4°C, was positively correlated with V. vulnificus concentrations in all matrices but sediments. Salinity, which ranged from 1 to 35 ppt, was negatively correlated with V. vulnificus levels in water and sediments but not in other matrices. Significant interaction effects between matrix and temperature support the hypothesis that temperature affects V. vulnificus concentrations differently in different matrices and that sediment habitats may serve as seasonal reservoirs for V. vulnificus. V. vulnificus levels in vegetation have not been previously measured and reveal an additional habitat for this autochthonous estuarine bacterium.

Comparative genomic analysis of clinical and environmental Vibrio vulnificus isolates revealed biotype 3 evolutionary relationships

In 1996 a common-source outbreak of severe soft tissue and bloodstream infections erupted among Israeli fish farmers and fish consumers due to changes in fish marketing policies. The causative pathogen was a new strain of Vibrio vulnificus, named biotype 3, which displayed a unique biochemical and genotypic profile. Initial observations suggested that the pathogen erupted as a result of genetic recombination between two distinct populations. We applied a whole genome shotgun sequencing approach using several V. vulnificus strains from Israel in order to study the pan genome of V. vulnificus and determine the phylogenetic relationship of biotype 3 with existing populations. The core genome of V. vulnificus based on 16 draft and complete genomes consisted of 3068 genes, representing between 59 and 78% of the whole genome of 16 strains. The accessory genome varied in size from 781 to 2044 kbp. Phylogenetic analysis based on whole, core, and accessory genomes displayed similar clustering patterns with two main clusters, clinical (C) and environmental (E), all biotype 3 strains formed a distinct group within the E cluster. Annotation of accessory genomic regions found in biotype 3 strains and absent from the core genome yielded 1732 genes, of which the vast majority encoded hypothetical proteins, phage-related proteins, and mobile element proteins. A total of 1916 proteins (including 713 hypothetical proteins) were present in all human pathogenic strains (both biotype 3 and non-biotype 3) and absent from the environmental strains. Clustering analysis of the non-hypothetical proteins revealed 148 protein clusters shared by all human pathogenic strains; these included transcriptional regulators, arylsulfatases, methyl-accepting chemotaxis proteins, acetyltransferases, GGDEF family proteins, transposases, type IV secretory system (T4SS) proteins, and integrases. Our study showed that V. vulnificus biotype 3 evolved from environmental populations and formed a genetically distinct group within the E-cluster. The unique epidemiological circumstances facilitated disease outbreak and brought this genotype to the attention of the scientific community.

Diversity and dynamics of the Vibrio community in well water used for drinking in Guinea-Bissau (West Africa)

Bacteria of the genus Vibrio are ubiquitous in aquatic environments and can be found either in culturable or in a viable but nonculturable (VBNC) state. The genus comprises many pathogenic species accountable for water and food-borne diseases that prove to be fatal, especially in developing countries, as in Guinea-Bissau (West Africa), where cholera is endemic. In order to ascertain the abundance and structure of Vibrio spp. community in well waters that serve as the sole source of water for the population, quantitative polymerase chain reaction (qPCR), PCR-denaturant gradient gel electrophoresis (DGGE), and cloning approaches were used. Results suggest that Vibrio spp. were present throughout the year in acidic, freshwater wells with a seasonal community composition shift. Vibrio spp. abundance was in accordance with the abundance found in coastal environments. Sequences closely related to pathogenic Vibrio species were retrieved from well water revealing exposure of the population to such pathogens. pH, ammonium, and turbidity, regulated by the rain pattern, seem to be the variables that contributed mostly to the shaping and selection of the Vibrio spp. community. These results reinforce the evidence for water monitoring with culture-independent methods and the clear need to create/recover water infrastructures and a proper water resources management in West African countries with similar environmental conditions.

Seaweeds and plastic debris can influence the survival of faecal indicator organisms in beach environments

The revised Bathing Water Directive (rBWD) introduces more stringent standards for microbial water quality and promotes more pro-active management of the beach environment through the production of a bathing water profile (BWP). The aim of this study was to determine whether living seaweeds in the littoral zone are colonised by faecal indicator organisms (FIOs), and to quantify the survival dynamics of waterborne Escherichia coli in microcosms containing senescing seaweeds. Living seaweed (Fucus spiralis) was not associated with FIO colonisation, although could be providing a protected environment in the underlying sand. Senescing seaweeds enhanced waterborne E. coli survival compared to plastic debris, with the brown seaweed Laminaria saccharina facilitating greater E. coli persistence than either Chondrus crispus or Ulva lactuca. This has important implications for FIO survival on bathing beaches as the majority of beach-cast biomass is composed of brown seaweeds, which could support significant levels of FIOs.

Distribution of virulence markers among Vibrio vulnificus isolates of clinical and environmental origin and regional characteristics in Japan

Background

Vibrio vulnificus is an opportunistic human pathogen that is widely distributed in estuarine environments and is capable of causing necrotizing fasciitis and sepsis. In Japan, based on epidemiological research, the incidences of V. vulnificus were concentrated in Kyusyu, mainly in coastal areas of the Ariake Sea. To examine the virulence potential, various genotyping methods have recently been developed. This study aimed to investigate the distribution of virulence markers among V. vulnificus isolates of clinical and environmental origin in three coastal areas with different infection incidences and to determine whether these isolates have the siderophore encoding gene viuB.

Methodology/Principal Findings

We examined the distribution of genotypes of the 16S ribosomal ribonucleic acid (rRNA) gene, vvhA, vcg, and capsular polysaccharide (CPS), and the presence of viuB in 156 isolates collected from patients and environmental samples in Japan. The environmental samples were collected from three coastal areas: the Ariake Sea, Ise & Mikawa Bay, and Karatsu Bay. The results showed disparity in the ratios of genotypes depending on the sample origins. V. vulnificus isolates obtained from patients were classified into the clinical type for all genotypes. In the environmental isolates, the ratios of the clinical type for genotypes of the 16S rRNA gene, vvhA, and vcg were in the order of the Ariake Sea>Ise & Mikawa Bay>Karatsu Bay. Meanwhile, CPS analysis showed no significant difference. Most isolates possessed viuB.

Conclusions

Many V. vulnificus belonging to the clinical type existed in the Ariake Sea. Three coastal areas with different infection incidences showed distinct ratios of genotypes. This may indicate that the distribution of clinical isolates correlates with the incidence of V. vulnificus infection.

Arabinose induces pellicle formation by Vibrio fischeri

Biofilms are multicellular communities of bacteria attached to a surface and embedded in a protective matrix. In many cases, the signals that induce biofilm formation are unknown. Here, we report that biofilm formation by the marine bacterium Vibrio fischeri can be induced by the addition of arabinose to LBS (Luria-Bertani-salt), a tryptone-based medium. Growth of cells in the presence of 0.2% arabinose, but not other sugars, induced the production of a pellicle at the air/liquid interfaces of static cultures. V. fischeri failed to grow on arabinose as the sole carbon source, suggesting that pellicle production did not occur as a result of increased growth, but experiments using the acid/base indicator phenol red suggested that V. fischeri may partially metabolize arabinose. Pellicle production was independent of the syp polysaccharide locus but was altered upon disruption of the bcs cellulose locus. Through a screen for mutants defective for pellicle production, we found that loss of motility disrupted the formation of the arabinose-induced pellicle. Among the ∼20 mutants that retained motility were strains with insertions in a putative msh pilus locus and a strain with a defect in yidK, which is involved in galactose catabolism. Mutants with the msh gene disrupted grew poorly in the presence of arabinose, while the yidK mutant appeared to be "blind" to the presence of arabinose. Finally, arabinose impaired symbiotic colonization by V. fischeri. This work thus identifies a novel signal and new pathways involved in control of biofilm formation by V. fischeri.

Development of a groEL gene-based species-specific multiplex polymerase chain reaction assay for simultaneous detection of Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus

AIMS

To develop an effective multiplex polymerase chain reaction (PCR) for the simultaneous detection of three important Vibrio species, Vibrio cholerae (Vc), V. parahaemolyticus (Vp) and V. vulnificus (Vv) using the groEL gene, a potential phylogenetic marker.

METHODS AND RESULTS

Three species-specific primer sets were designed to target Vc, Vp and Vv. A total of 131 Vibrio and non-Vibrio strains were used to determine the specificity and sensitivity of primers. The primers produced specific PCR fragments from all target species strains and did not cross-react with other Vibrio and non-Vibrio species. This PCR method showed good efficiency in detecting coexisting target species in the same sample with a detection limit of 100 pg of Vc, Vp and Vv from mixed purified DNA. Detection of three target species was also possible from artificially inoculated shellfish, flounder and sea water.

CONCLUSIONS

The groEL gene is a potential marker for accurate simultaneous detection of Vc, Vp and Vv and could be used to detect these species in environmental and clinical samples.

SIGNIFICANCE AND IMPACT OF THE STUDY

This newly developed multiplex PCR is a useful and cost-effective method that is applicable in a disease-outbreak prediction system and may provide an effective tool for both the epidemiologist and ecologist.

Overlapping and unique contributions of two conserved polysaccharide loci in governing distinct survival phenotypes in Vibrio vulnificus

As an aetiological agent of bacterial sepsis and wound infections, Vibrio vulnificus is unique among the Vibrionacea. Its continued environmental persistence and transmission are bolstered by its ability to colonize shellfish and form biofilms on various marine biotic surfaces. We previously identified a polysaccharide locus, brp, which contributes to the survival phenotypes of biofilm formation, rugose colony formation and stress resistance. Here, we describe a second polysaccharide locus, rbd (regulation of biofilm development), which also enhanced biofilm formation when expressed. Despite this functional overlap, the development of stress resistance and rugosity could be uniquely attributed to brp expression, whereas rbd expression augmented aggregate formation. Simultaneous expression of both loci led to the formation of a dramatic pellicle and maximum biofilm formation. Unlike the brp locus, transcription of the rbd locus was regulated not by c-di-GMP, but by a response regulator (RbdG) that was encoded within the locus. We propose that the ability to regulate the expression of polysaccharides with overlapping and unique characteristics in response to different environmental cues enables V. vulnificus to 'fine tune' its biofilm lifestyle to the prevailing environmental conditions and maximally benefit from the characteristics associated with each polysaccharide.

Distribution of Vibrio alginolyticus-like species in Shenzhen coastal waters, China

We investigated the distribution of vibrios in Shenzhen coastal waters in order to obtain valuable information for the aquaculture industry and a health warning system. Quantities of vibrios from surface waters ranged from 0 to 4.40×10(4) CFUs mL(-1) in April (spring), while from 0 to 2.57×10(3) CFUs mL(-1) in September (autumn); the abundance of V. alginolyticus-like species from surface water ranged from 0 to 6.72×10(3) CFUs mL(-1) in April (spring) and from 0 to 1.28×10(3) CFUs mL(-1) in September (autumn); higher counts were observed in spring. The V. alginolyticus-like species was dominant in Shenzhen coastal waters, with the highest abundance in the clean region (stations YMK001 and GDN064) in April, suggesting that Vibrio spp. were naturally occurring bacteria in marine environments. The correlation between the abundance of vibrios (including V. alginolyticus-like species) and environmental factors varied in different regions and different seasons. There were no vibrios detected when the salinity was less than 11.15‰ in the Zhujiang River estuary, which indicated that salinity played a key role in the distribution of vibrios and V. alginolyticus-like species.

Foodborne pathogens in retail oysters in south China

OBJECTIVE

To investigate the occurrence of important foodborne pathogens in shellstock Pacific oysters in the food markets in South China.

METHODS

From July 2007 to June 2008, retail oysters were collected in different seasons from South China and analyzed for the prevalence and levels of Listeria monocytogenes, Vibrio vulnificus and Vibrio parahaemolyticus.

RESULTS

None of L. monocytogenes could be detected in any of the 202 oyster samples tested, while E vulnificus and V. parahaemolyticus could be detected in 67 (54.9%) and 109 (89.3%) of the 122 oyster samples analyzed, respectively, with an MPN (most probable number) value greater than or equal to 3. V. vulnificus and V. parahaemolyticus with a more than 102 MPN/g were found in 36 (29.5%) and 59 (48.4%) of the 122 oyster samples, respectively. The tdh and trh genes were detected in 4 (0.3%) and 8 (0.6%) of the 1 349 V parahaemolyticus isolates, respectively. Of the 122 samples, 4 (3.3%) was positive for either tdh or trh. The levels of V. vulnificus and total V. parahaemolyticus in oysters in South China varied in different seasons.

CONCLUSION

V. vulnificus and pathogenic V. parahaemolyticus are frequently found in oysters in south China, which may pose a potential threat to public health. Data presented here will be useful for the microbiological risk assessment in oysters in China.

Detection of Vibrio vulnificus in seafood, seawater and wastewater samples from a Mediterranean coastal area

Vibrio vulnificus is an opportunistic human pathogen that may cause gastroenteritis, severe necrotizing soft-tissue infections and primary septicaemia, with a high lethality rate. Illness is associated to ingestion of seafood or to the exposure of contaminated water. The aim of this work was to determine the occurrence of V. vulnificus in water and seafood samples from a coastal area near the Mediterranean (Valencia, Spain). A TaqMan probe-based real-time PCR assay was optimised and applied to 22 sea water, 42 raw sewage and 40 seafood samples. Results were compared with those obtained for culture isolation. The detection level of the PCR assay was 10 CFU g⁻¹ in inoculated samples. Seven seawater, four shellfish and six wastewater samples were positive by real time PCR. V. vulnificus was isolated from two oyster, three sea water and two wastewater samples. All the strains were obtained after 20 h enrichment, except for wastewater strains, which were isolated directly from the sample. To our knowledge, this is the first report on the isolation of V. vulnificus from sewage in Spain. Our results about the presence of V. vulnificus in food and environmental samples are strong enough to consider that the organism may represent a human health hazard in our geographical area.

Hemochromatosis and Vibrio vulnificus wound infections

There are several reports of persons with hemochromatosis and Vibrio vulnificus primary septicemia, but few accounts of persons with hemochromatosis and V. vulnificus wound infection. A 58-year-old white man developed infection of a forearm injury exposed to seawater in the Gulf of Mexico near the Alabama coast. At age 66, he was diagnosed to have hemochromatosis. Transferrin saturation was 89% and serum ferritin was 4761 pmol/L. HFE genotype was C282Y/C282Y. Serum levels of hepatic enzymes, glucose, IgG, IgA, and IgM, and blood levels of T, B, and natural killer cells were normal. We identified previous reports of only 2 similar cases: a woman from Alabama and a man from northern Australia. Mean age of the 3 subjects was 51 years at diagnosis of infection. Each had elevated serum iron measures or iron overload complications; both men were diagnosed to have hemochromatosis after they developed infection. Each of the 3 had recent exposure of a wound on an extremity to seawater, rapid development of a necrotizing soft tissue infection that required debridement and skin grafting, and positive wound or blood cultures. Each subject survived the infection. V. vulnificus wound infection occurs in some persons with hemochromatosis, but the risk of infection may be small. All patients with V. vulnificus infections should be evaluated for hemochromatosis, iron overload, and liver disorders.

csrA inhibits the formation of biofilms by Vibrio vulnificus

PCR screening of the shellfish-borne pathogen Vibrio vulnificus revealed csrA-negative strains, and these strains formed increased biofilm compared to csrA-positive strains. Complementation in trans with csrA resulted in reduced biofilm formation, similar to that by csrA(+) strains. Our results provide evidence that csrA inhibits biofilm formation in V. vulnificus.