Primary Septicemia Research Articles

Dissemination of pathogenic bacteria is reinforced by a MARTX toxin effector duet

Multiple bacterial genera take advantage of the multifunctional autoprocessing repeats-in-toxin (MARTX) toxin to invade host cells. Secretion of the MARTX toxin by Vibrio vulnificus, a deadly opportunistic pathogen that causes primary septicemia, the precursor of sepsis, is a major driver of infection; however, the molecular mechanism via which the toxin contributes to septicemia remains unclear. Here, we report the crystal and cryo-electron microscopy (EM) structures of a toxin effector duet comprising the domain of unknown function in the first position (DUF1)/Rho inactivation domain (RID) complexed with human targets. These structures reveal how the duet is used by bacteria as a potent weapon. The data show that DUF1 acts as a RID-dependent transforming NADase domain (RDTND) that disrupts NAD+ homeostasis by hijacking calmodulin. The cryo-EM structure of the RDTND-RID duet complexed with calmodulin and Rac1, together with immunological analyses in vitro and in mice, provide mechanistic insight into how V. vulnificus uses the duet to suppress ROS generation by depleting NAD(P)+ and modifying Rac1 in a mutually-reinforcing manner that ultimately paralyzes first line immune responses, promotes dissemination of invaders, and induces sepsis. These data may allow development of tools or strategies to combat MARTX toxin-related human diseases.

Characterization of Outer Membrane Vesicles Produced by Vibrio vulnificus.

Vibrio vulnificus (V. vulnificus) is a halophilic gram-negative bacterium that inhabits coastal warm water and induce severe diseases such as primary septicemia. To investigate the mechanisms of rapid bacterial translocation on intestinal infection, we focused on outer membrane vesicles (OMVs), which are extracellular vesicles produced by Gram-negative bacteria and deliver virulence factors. However, there are very few studies on the pathogenicity or contents of V. vulnificus OMVs (Vv-OMVs). In this study, we investigated the effects of Vv-OMVs on host cells. Epithelial cells INT407 were stimulated with purified OMVs and morphological alterations and levels of lactate dehydrogenase (LDH) release were observed. In cells treated with OMVs, cell detachment without LDH release was observed, which exhibited different characteristics from cytotoxic cell detachment observed in V. vulnificus infection. Interestingly, OMVs from a Vibrio Vulnificus Hemolysin (VVH) and Multifunctional-autoprocessing repeats-in -toxin (MARTX) double-deletion mutant strain also caused cell detachment without LDH release. Our results suggested that the proteolytic function of a serine protease contained in Vv-OMVs may contribute to pathogenicity of V. vulnificus by assisting bacterial translocation. This study reveals a new pathogenic mechanism during V. vulnificus infections. J. Med. Invest. 71 : 102-112, February, 2024.

Vibrio parahaemolyticus in fish and shellfish of animal origin from establishments in the port of Chicxulub, Yucatan, Mexico

Introduction: Vibrio parahaemolyticus is a human pathogen that is widely distributed in marine environments. This organism is frequently isolated from a variety of raw seafood products, particularly fish and shellfish. Consumption of raw or undercooked fish and shellfish contaminated with Vibrio parahaemolyticus can lead to the development of acute gastroenteritis characterized by diarrhea, headache, vomiting, nausea, and abdominal cramps. It has also been isolated from wound infections and septicemias. Most cases are non–fatal. This bacterium is recognized as the leading cause of human gastroenteritis associated with fish and shellfish consumption in the United States of America and an important fish and shellfish borne pathogen worldwide. Chile faced its first outbreak in 1997–1998. Subsequently, outbreaks and cases have continued to occur, all associated with the consumption of fish and shellfish. Objective: To determine if raw seafood, marinated without heat, partially cooked with heat and completely cooked with heat that are sold for human consumption in establishments in the port of Chicxulub, Yucatan, Mexico, represent potential risk factors for the development of acute gastroenteritis, wound infection, primary septicemia and secondary septicemia by Vibrio parahaemolyticus species. Material and methods: Study conducted on a representative sample selected from the total of two hundred samples from thirty–eight establishments. From July 1 to December 31, 2021, one hundred thirty two samples of seafood were studied. Using the Cornfield Method, the estimation interval was constructed at the 95% confidence level. Results: In thirty–seven (28.03%) samples an equal number of strains were isolated whose biochemical characteristics corresponded to Vibrio parahaemolyticus. The prevalences obtained in raw marine foods, marinated without heat, partially cooked with heat and completely cooked with heat were 35.59%, 45.45%, 22.45% and 0.00%. The Cornfield estimation interval at the 95% confidence level for Vibrio parahaemolyticus was 13.56% ≤ P ≤ 42.50%. Conclusion: Raw seafood, marinated without heat and partially cooked with heat represent potential risk factors for Vibrio parahaemolyticus for the development of acute gastroenteritis, wound infection, primary septicemia, and secondary septicemia.

Vibrio vulnificus in seafood of animal origin from establishments in the city of Telchac Puerto, Yucatan, Mexico

Objective. To determine if raw seafood, marinated without heat, partially cooked with heat, and completely cooked with heat that are sold for human consumption in establishments in the city of Telchac Puerto, Yucatan, Mexico, represent potential risk factors for the development of acute gastroenteritis, wound infection, primary septicemia and secondary septicemia by Vibrio vulnificus species. Material and methods. Study conducted on a representative sample (n= 132) selected from the total of 200 samples from 38 establishments. From July 1 to December 31, 2019, 132 samples of seafood were studied. Using the Cornfield method, the estimation interval was constructed at the 95% confidence level. Results. In 37 (28.03%) samples an equal number of strains were isolated whose biochemical characteristics corresponded to Vibrio vulnificus. The prevalences obtained in raw marine foods, marinated without heat, partially cooked with heat and completely cooked with heat were 35.59%, 45.45%, 22.45% and 0.00%. The Cornfield estimation interval at the 95% confidence level for Vibrio vulnificus was 13.56% ≤ P ≤ 42.50%. Conclusion. Raw seafood, marinated without heat, and partially cooked with heat represent potential risk factors for Vibrio vulnificus for the development of acute gastroenteritis, wound infection, primary septicemia, and secondary septicemia.

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.

Vibrio alginolyticus in marine foods of animal origin from establishments in the port of Chabihau, Yucatan, Mexico

To determine if the marine foods of animal origin that are sold in establishments in the port of Chabihau, Yucatan, Mexico, represent potential risk factors for the Vibrio alginolyticus species for the development of acute gastroenteritis, wound infection, ear infection and primary septicemia. Three hundred and ninety seafood samples were studied: [298 (76.41%) raw, 8 (2.05%) marinated without heat, 77 (19.74%) partially cooked with heat and 7 (1.79%) completely cooked with heat]. For the homogenization and enrichment of the samples, as well as for the isolation and identification of the Vibrio alginolyticus species, we proceeded according to the methodology described in the eighth edition of the Bacteriological Analytical Manual (FDA). The criteria used in conducting the hypothesis tests for the difference between two percentages was based on the recommendations made by Cochran. The prevalences obtained in raw seafood, marinated without heat, partially cooked with heat and completely cooked with heat were, respectively, 7.72% (23/298), 0.00% (0/8), 7.79% (6/77) and 0.00% (0/7). In 29 (7.44%) samples an equal number of strains were isolated whose biochemical characteristics corresponded to the Vibrio alginolyticus species. It is concluded that raw seafood and partially cooked seafood represent potential risk factors for the Vibrio alginolyticus species for the development of acute gastroenteritis, wound infection, ear infection and primary septicemia.

Heatwave-associated Vibrio infections in Germany, 2018 and 2019.

Background Vibrio spp. are aquatic bacteria that prefer warm seawater with moderate salinity. In humans, they can cause gastroenteritis, wound infections, and ear infections. During the summers of 2018 and 2019, unprecedented high sea surface temperatures were recorded in the German Baltic Sea.AimWe aimed to describe the clinical course and microbiological characteristics of Vibrio infections in Germany in 2018 and 2019.MethodsWe performed an observational retrospective multi-centre cohort study of patients diagnosed with domestically-acquired Vibrio infections in Germany in 2018 and 2019. Demographic, clinical, and microbiological data were assessed, and isolates were subjected to whole genome sequencing and antimicrobial susceptibility testing.ResultsOf the 63 patients with Vibrio infections, most contracted the virus between June and September, primarily in the Baltic Sea: 44 (70%) were male and the median age was 65 years (range: 2–93 years). Thirty-eight patients presented with wound infections, 16 with ear infections, six with gastroenteritis, two with pneumonia (after seawater aspiration) and one with primary septicaemia. The majority of infections were attributed to V. cholerae (non–O1/non-O139) (n = 30; 48%) or V. vulnificus (n = 22; 38%). Phylogenetic analyses of 12 available isolates showed clusters of three identical strains of V. vulnificus, which caused wound infections, suggesting that some clonal lines can spread across the Baltic Sea.ConclusionsDuring the summers of 2018 and 2019, severe heatwaves facilitated increased numbers of Vibrio infections in Germany. Since climate change is likely to favour the proliferation of these bacteria, a further increase in Vibrio-associated diseases is expected.

Vibrio Alginolyticus in Marine Foods of Animal Origin From Establishments in the Port of Chabihau, Yucatan, Mexico

To determine if the marine foods of animal origin that are sold in establishments in the port of Chabihau, Yucatan, Mexico, represent potential risk factors for the Vibrio alginolyticus species for the development of acute gastroenteritis, wound infection, ear infection and primary septicemia. Three hundred and ninety seafood samples were studied: [298 (76.41%) raw, 8 (2.05%) marinated without heat, 77 (19.74%) partially cooked with heat and 7 (1.79%) completely cooked with heat]. For the homogenization and enrichment of the samples, as well as for the isolation and identification of the Vibrio alginolyticus species, we proceeded according to the methodology described in the eighth edition of the Bacteriological Analytical Manual (FDA). The criteria used in conducting the hypothesis tests for the difference between two percentages was based on the recommendations made by Cochran. The prevalences obtained in raw seafood, marinated without heat, partially cooked with heat and completely cooked with heat were, respectively, 7.72% (23/298), 0.00% (0/8), 7.79% (6/77) and 0.00% (0/7). In 29 (7.44%) samples an equal number of strains were isolated whose biochemical characteristics corresponded to the Vibrio alginolyticus species. It is concluded that raw seafood and partially cooked seafood represent potential risk factors for the Vibrio alginolyticus species for the development of acute gastroenteritis, wound infection, ear infection and primary septicemia.

Vibrio alginolyticus in marine foods of animal origin from establishments in the port of Chabihau, Yucatan, Mexico

To determine if the marine foods of animal origin that are sold in establishments in the port of Chabihau, Yucatan, Mexico, represent potential risk factors for the Vibrio alginolyticus species for the development of acute gastroenteritis, wound infection, ear infection and primary septicemia. Three hundred and ninety seafood samples were studied: [298 (76.41%) raw, 8 (2.05%) marinated without heat, 77 (19.74%) partially cooked with heat and 7 (1.79%) completely cooked with heat]. For the homogenization and enrichment of the samples, as well as for the isolation and identification of the Vibrio alginolyticus species, we proceeded according to the methodology described in the eighth edition of the Bacteriological Analytical Manual (FDA). The criteria used in conducting the hypothesis tests for the difference between two percentages was based on the recommendations made by Cochran. The prevalences obtained in raw seafood, marinated without heat, partially cooked with heat and completely cooked with heat were, respectively, 7.72% (23/298), 0.00% (0/8), 7.79% (6/77) and 0.00% (0/7). In 29 (7.44%) samples an equal number of strains were isolated whose biochemical characteristics corresponded to the Vibrio alginolyticus species. It is concluded that raw seafood and partially cooked seafood represent potential risk factors for the Vibrio alginolyticus species for the development of acute gastroenteritis, wound infection, ear infection and primary septicemia.

Case of an Exotic Skin and Soft Tissue Infection Associated with Cyclone Ockhi

Vibrio vulnificus is a halophilic marine gram-negative bacillus that is known to cause fulminant primary septicemia and complicated skin and soft tissue infections in humans. Vibrio vulnificus is referred to as flesh-eating bacteria. In the absence of timely detection and treatment, it results in sepsis with mortality of 50% and septic shock with mortality as high as 100%. Primary septicemia occurs following ingestion of contaminated seafood, and wound infections are acquired following exposure of open wounds to contaminated seawater. Early clinical suspicion and initiation of the appropriate antibiotics is essential to ensure good clinical outcome in case of Vibrio vulnificus septicemia. Here we report the case of a fisherman injured in cyclone Ockhi admitted to our hospital with lower limb cellulitis, who was diagnosed as Vibrio vulnificus wound infection. This case emphasizes the importance of history and clinical examination in antibiotic stewardship.

The widespread presence of a family of fish virulence plasmids in Vibrio vulnificus stresses its relevance as a zoonotic pathogen linked to fish farms

ABSTRACT Vibrio vulnificus is a pathogen of public health concern that causes either primary septicemia after ingestion of raw shellfish or secondary septicemia after wound exposure to seawater. In consequence, shellfish and seawater are considered its main reservoirs. However, there is one aspect of its biology that is systematically overlooked: its association with fish in its natural environment. This association led in 1975 to the emergence of a zoonotic clade within phylogenetic lineage 2 following successive outbreaks of vibriosis in farmed eels. Although this clade is now worldwide distributed, no new zoonotic clades were subsequently reported. In this work, we have performed phylogenetic, genomic and functional studies to show that other zoonotic clades are in fact present in 4 of the 5 lineages of the species. Further, we associate these clades, most of them previously but incompletely described, with the acquisition of a family of fish virulence plasmids containing genes essential for resistance to the immune system of certain teleosts of interest in aquaculture. Consequently, our results provide several pieces of evidence about the importance of this species as a zoonotic agent linked to fish farms, as well as on the relevance of these artificial environments acting as drivers that accelerate the evolution of the species.

Drug Resistant Strains of Vibrio vulnificus from Sea Mud in Prince of Songkla University, Pattani Campus and Some Shells in Pattani Seafood Markets

Vibrio vulnificus (Vv) is an opportunistic human pathogen that may cause primary septicemia, necrosis and gastroenteritis. It can be isolated from marine animals and marine environment. This research aimed to isolate and characterize the drug resistant strains of Vibrio vulnificus from sea mud within Prince of Songkla University, Pattani campus and closed areas and from green mussel (Perna viridis) and bloody cockle (Tegillarca granosa) in seafood markets. The result found that from 43 sea mud samples, the total of 4 strains of Vibrio vulnificus were isolated from Pattani estuary 1 strain, Pattani estuary 2 strains and Rusamilae estuary 1 strain. The 3 strains of Vibrio vulnificus were detected in 10 samples of green mussel and 1 strain in bloody cockle. The antimicrobial susceptibilities of Vibrio vulnificus isolates recovered from sea mud and shells were determined. All isolates were sensitive to ceftazidime and resistant to ampicillin and clindamycin.

The role of Vibrio vulnificus virulence factors and regulators in its infection-induced sepsis.

Due to the development of Marine aquaculture, infections caused by Vibrio vulnificus are common all over the world. Symptoms of V. vulnificus infection vary from gastrointestinal illness to septicemia. After infection with V. vulnificus, some patients showed gastrointestinal symptoms, including vomiting, fever, diarrhea, and so on. Others appeared wound infection at the site of contact with bacteria, and even developed sepsis. Once it develops into sepsis, the prognosis of patients is very poor. However, its underlying pathogenic mechanism remains largely undetermined. Growing evidence shows that it can induce primary septicemia mainly via essential virulence factors and regulators. Therefore, it is important to identify the factors that play roles in sepsis. In this review, we systematically expounded the role of V. vulnificus virulence factors and regulators in its infection-induced sepsis in order to provide useful information for the treatment and prevention of V. vulnificus.

Vibrio vulnificus cytolysin induces inflammatory responses in RAW264.7 macrophages through calcium signaling and causes inflammation in vivo

Vibrio vulnificus is a food-borne marine pathogen that causes both life-threatening primary septicemia and necrotizing wound infections which accompany severe inflammation. Cytolysin is a very powerful virulence factor of V. vulnificus and is one of the likely candidates in the pathogenesis of V. vulnificus infections. However, the pathogenetic roles of cytolysin in V. vulnificus-induced inflammation are not well understood. In this study, we used the recombinant protein Vibrio vulnificus cytolysin (VVC) to demonstrate that VVC can induce inflammatory responses in RAW264.7 macrophages. Low dose (<5 μg/ml) VVC had no impact on cell viability and induced pro-inflammatory cytokines production in RAW264.7 macrophages such as IL-6 and TNF-α. Moreover, VVC induced p65, p38, ERK1/2, and AKT phosphorylation in RAW264.7 macrophages. We further demonstrated that BAPTA-AM, a specific intracellular calcium chelator, inhibited VVC-induced inflammatory responses including pro-inflammatory cytokines production and inflammatory signaling activation in RAW264.7 macrophages. In addition, VVC primed rather than actived NLRP3 inflammasome in RAW264.7 macrophages. To determine whether VVC have a direct inflammatory effect on the host, we examined the effects of VVC injected into the skin of mice. VVC stimulated a significant induction of mRNAs for the pro-inflammatory cytokine IL-6 and inflammatory chemokines such as MCP-1 and IP-10. Histology data also showed that VVC caused inflammatory responses in the skin of mice. Collectively, our findings indicated that VVC induced inflammatory responses in RAW264.7 macrophages and in vivo and suggested the possibility of targeting VVC as a strategy for the clinical management of V. vulnificus-induced inflammatory responses.

FATAL RASH

SESSION TITLE: Critical Care cases 2 SESSION TYPE: Fellow Case Reports PRESENTED ON: 10/08/2018 03:15 PM - 04:15 PM INTRODUCTION: Vibrio vulnificus is a Gram-negative bacillus found in warm coastal waters. There are three clinical syndromes: primary septicemia, wound infections and gastrointestinal disease. Mortality rates of >50% have been reported in patients who present with primary septicemia. We describe a case of V. vulnificus presenting with septic shock and a violaceous annular rash with hemorrhagic bullae. CASE PRESENTATION: A 52 year old male with chronic alcoholism presented with fever, dyspnea and rash over upper and lower limbs for 2 days. He was febrile, tachypneic, and had a tachycardia of 140 beats/minute, hypotension with a blood pressure of 90/61mmHg, and pulse oximetry of 100% on room air. A violaceous annular rash over face, trunk, and upper limbs and hemorrhagic bullae over lower limbs was observed. There was no overlying cellulitis or necrotizing fasciitis. He was jaundiced, and laboratory data revealed a depressed white cell count, thrombocytopenia, high anion gap metabolic acidosis with hyperlactemia, acute renal failure and disseminated intravascular coagulation. He was intubated and mechanically ventilated and required dual vasopressor support following aggressive fluid resuscitation. Intravenous meropenem and doxycycline were promptly administered. Chest radiograph was normal and computed tomography of the abdomen and pelvis revealed ascites and hepatomegaly. Further history revealed no recent seawater exposure or seafood ingestion. A Gram-negative bacillus which later identified as V. vulnificus was isolated from the initial blood cultures and antibiotics were changed to IV ceftriaxone and doxycycline. Despite appropriate antibiotics and supportive management, he died 20 hours after. DISCUSSION: V. vulnificus infection can have an aggressive clinical course with significant morbidity and mortality. In this case, the patient died of multi-organ failure despite timely and appropriate antibiotics, and maximal supportive treatment. High-risk patients include those with chronic liver disease and chronic alcoholism; usually with a positive history of shellfish consumption or seawater exposure. Hypotension in the first 12 hours of presentation and leukopenia predicts for poorer outcomes. High bacterial densities of V vulnificus are seen with higher water temperatures of tropical seawater. CONCLUSIONS: High clinical suspicion of V. vulnificus infection is warranted in tropical coastline areas for patients presenting with severe sepsis and widespread violaceous annular rash with hemorrhagic bullae. Reference #1: Horseman MA, Surani S. A comprehensive review of Vibrio vulnificus: an important cause of severe sepsis and skin and soft-tissue infection. Int J Infect Dis. 2011 Mar;15(3):e157-66. Reference #2: Klontz KC, Lieb S, Schreiber M, Janowski HT, Baldy LM, Gunn RA. Syndromes of Vibrio vulnificus infections. Clinical and epidemiologic features in Florida cases, 1981-1987. Ann Intern Med. 1988 Aug 15;109(4):318-23. DISCLOSURES: No relevant relationships by Liesel Fong, source=Web Response No relevant relationships by Pyng Lee, source=Web Response No relevant relationships by Sui An Lie, source=Web Response

Vibrio vulnificus infection: a persistent threat to public health.

Vibrio vulnificus is a gram-negative bacterium that can cause serious, potentially fatal infections. V. vulnificus causes three distinct syndromes: an overwhelming primary septicemia caused by consuming contaminated seafood, wound infections acquired when an open wound is exposed to contaminated warm seawater, and gastrointestinal tract-limited infections. Case-fatality rates are higher than 50% for primary septicemia, and death typically occurs within 72 hours of hospitalization. Risk factors for V. vulnificus infection include chronic liver disease, alcoholism, and hematological disorders. When V. vulnificus infection is suspected, appropriate antibiotic treatment and surgical interventions should be performed immediately. Third-generation cephalosporin with doxycycline, or quinolone with or without third-generation cephalosporin, may be potential treatment options for patients with V. vulnificus infection.

Ethylenediaminetetraacetic Acid Inhibits Vibrio Vulnificus-Induced Dendritic Cell Apoptosis by Lowering [Ca2+

Background/Aims: Vibrio vulnificus (V. vulnificus) is a Gram-negative marine bacterium that can cause life-threatening primary septicemia, especially in the innate immune system. But how V. vulnificus affects and acts on dendritic cells (DC) is not well understood. The aim of the present study is to investigate [Ca²⁺]_i change and the expression of the mTor-STAT3-Bcl-2 signaling pathway in V. vulnificus B2-induced DC apoptosis, and explore the protective effect of ethylenediaminetetraacetic acid (EDTA) against DC apoptosis in a V. vulnificus B2 and DC2.4 cell coculture infection model, using EDTA as an intervenient. Methods: The apoptosis rate, [Ca²⁺]_i, and the expression of STAT3, m-Tor and Bcl-2 were detected by cytometry, Fluo-8-AM and Western blotting respectively. Results: The results demonstrated that EDTA inhibited the increase of [Ca²⁺]_i, upregulated the expression of m-Tor-STAT3-Bcl-2 signaling pathway, and protected DC against V. vulnificus B2-induced apoptosis. Conclusions: EDTA inhibits V. Vulnificus-induced DC apoptosis by lowering [Ca²⁺]_i via m-Tor-STAT3-Bcl-2 signaling pathway.

Vibrio vulnificus: new insights into a deadly opportunistic pathogen.

Vibrio vulnificus is a Gram-negative aquatic bacterium first isolated by the United States (US) Centers for Disease Control and Prevention (CDC) in 1964. This bacterium is part of the normal microbiota of estuarine waters and occurs in high numbers in molluscan shellfish around the world, particularly in warmer months. Infections in humans are derived from consumption of seafood produce and from water exposure. Vibrio vulnificus is a striking and enigmatic human pathogen, yet many aspects related to its biology, genomics, virulence capabilities and epidemiology remain elusive and poorly understood. This pathogen is responsible for over 95% of seafood-related deaths in the United States, and carries the highest fatality rate of any food-borne pathogen. Indeed, infections associated with this pathogen that progress to primary septicaemia have a similar case fatality rate to category BSL 3 and 4 pathogens, such as anthrax, bubonic plague, Ebola and Marburg fever. Interestingly, V. vulnificus infections disproportionately affect males (∼85% of cases) and older patients (>40 years), especially those with underlying conditions such as liver diseases, diabetes and immune disorders. New insights from molecular studies and comparative genomic approaches have offered tantalising insights into this pathogen. A recent increase and geographical spread in reported infections, in particular wound cases, underlines the growing international importance of V. vulnificus, particularly in the context of coastal warming. We outline and explore here a range of current data gaps regarding this important pathogen, and provide some current thoughts on approaches to elucidate key aspects associated with this bacterium.

Immunogenicity and protective efficacy of Vibrio vulnificus flagellin protein FlaB in a wound infection model.

Vibrio vulnificus is known as an opportunistic bacterial pathogen that causes primary septicemia and wound infection in humans. Recently, the incidence of wound infection by V. vulnificus is increasing in warm countries. In this study, we examined a vaccine antigen against V. vulnificus in mice. FlaB, a component protein of the V. vulnificus flagellum, was expressed as a recombinant protein, named rFlaB. After immunization of mice with rFlaB, the mice were challenged by subcutaneous inoculation with V. vulnificus. Bacterial burdens in muscular tissue at the infection site in rFlaB-immunized mice were significantly decreased compared with those of control mice. We found that rFlaB immunization can partially suppress proliferation of V. vulnificus at the local infection site.

Contribution of efflux systems to the detergent resistance, cytotoxicity, and biofilm formation of Vibrio vulnificus

Vibrio vulnificus causes primary septicemia in immunocompromised patients following consumption of contaminated seafood. In order to cause infection, pathogenic bacteria require mechanisms to defend against the action of host-derived antimicrobials, and may accomplish this task through the expression of efflux pumps. Herein, we investigated the influence of bile salts on the antimicrobial resistance mechanisms in V. vulnificus, and the contribution of efflux pumps to the bacterium's detergent resistance and virulence characteristics. Bacterial cells treated with either bile salts or Triton X-100 developed enhanced detergent resistance relative to the untreated control, and also showed increased expression of genes encoding resistance-nodulation-division (RND) efflux pumps. Further investigation on V. vulnificus mutants deficient in RND efflux pump VexB revealed them to be more susceptible to nonionic detergents. In addition, an RND efflux pump triple mutant, ΔvexBHZ, exhibited increased cytotoxicity and enhanced biofilm formation. In summary, our data indicate that V. vulnificus RND efflux pump VexB plays a key role in the resistance to nonionic detergents. Furthermore, the expression levels of efflux pumps affect the antimicrobial resistance and are involved in modulating the biofilm formation and cytotoxicity of this pathogen.