Small Bowel Obstruction Secondary to a Spontaneous Intramural Jejunal Hematoma

N/a.

Dupilumab for atopic dermatitis: a real-world portuguese multicenter retrospective study

Introduction: Atopic dermatitis (AD) is a difficult-to-treat inflammatory skin disease with a high impact on patients' quality of life. Dupilumab, an IL-4 and IL-13 inhibitor, was the first monoclonal antibody approved for the treatment of moderate-to-severe AD and is currently approved in patients aged 6 or older.Methods: This is a nationwide, multicenter, retrospective, 48-week study designed by the Portuguese Group of AD to assess real-world efficacy and safety of dupilumab for the treatment of AD.Results: A total of 169 patients were enrolled, with a mean disease duration of 22.75 (±11.98) years. The percentage of patients achieving an improvement of at least 75% in Eczema Area and Severity Index (EASI) compared to baseline (EASI75 response) at weeks 12 and 48 was 67.6% and 74.1%, respectively. In the same timepoints, 25.0% and 44.1% achieved an EASI90 response. Patient-reported outcome measures also improved throughout the study period. Regarding safety, 32.0% of the patients developed adverse events, with conjunctivitis (26.6%), persistent facial erythema (4.7%), and arthritis/arthralgia (3.6%) as the more frequently reported.Conclusion: Data from real-world populations are crucial to guide clinicians in their daily decisions. This study provides data demonstrating that dupilumab is an effective and safe therapeutic option for AD.

Management of congenital ichthyoses: European guidelines of care, part one

These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an expert conference held in Toulouse in 2016 and a consensus on the discussions. They summarize evidence and expert-based recommendations and are intended to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part one, covering topical therapies, systemic therapies, psychosocial management, communicating the diagnosis and genetic counselling.

Management of congenital ichthyoses: European guidelines of care, part two

These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an expert conference held in Toulouse in 2016, and a consensus on the discussions. These guidelines summarize evidence and expert-based recommendations and intend to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part two, covering the management of complications and the particularities of some forms of congenital ichthyosis.

Comprehensive identification of Vibrio vulnificus genes required for growth in human serum

Vibrio vulnificus can be a highly invasive pathogen capable of spreading from an infection site to the bloodstream, causing sepsis and death. To survive and proliferate in blood, the pathogen requires mechanisms to overcome the innate immune defenses and metabolic limitations of this host niche. We created a high-density transposon mutant library in YJ016, a strain representative of the most virulent V. vulnificus lineage (or phylogroup) and used transposon insertion sequencing (TIS) screens to identify loci that enable the pathogen to survive and proliferate in human serum. Initially, genes underrepresented for insertions were used to estimate the V. vulnificus essential gene set; comparisons of these genes with similar TIS-based classification of underrepresented genes in other vibrios enabled the compilation of a common Vibrio essential gene set. Analysis of the relative abundance of insertion mutants in the library after exposure to serum suggested that genes involved in capsule biogenesis are critical for YJ016 complement resistance. Notably, homologues of two genes required for YJ016 serum-resistance and capsule biogenesis were not previously linked to capsule biogenesis and are largely absent from other V. vulnificus strains. The relative abundance of mutants after exposure to heat inactivated serum was compared with the findings from the serum screen. These comparisons suggest that in both conditions the pathogen relies on its Na⁺ transporting NADH-ubiquinone reductase (NQR) complex and type II secretion system to survive/proliferate within the metabolic constraints of serum. Collectively, our findings reveal the potency of comparative TIS screens to provide knowledge of how a pathogen overcomes the diverse limitations to growth imposed by serum.

Acute Hemorrhagic Edema of Infancy

Acute Hemorrhagic Edema of Infancy is a small vessel leucocytoclastic vasculitis affecting young infants. It is characterized by large, target-like, macular to purpuric plaques predominantly affecting the face, ear lobes and extremities. Non-pitting edema of the distal extremities and low-grade fever may also be present. Extra-cutaneous involvement is very rare. Although the lesions have a dramatic onset in a twenty-four to forty-eight hour period, usually the child has a non-toxic appearance. In most cases there are no changes in laboratory parameters. The cutaneous biopsy reveals an inflammatory perivascular infiltrate. It is a benign and auto-limited disease, with complete resolution within two to three weeks leaving no sequelae in the majority of cases. No recurrences are described. We report a case of a 42-day old girl admitted at our hospital with Acute Hemorrhagic Edema of Infancy.

Characterization of PAMP/PRR interactions in European eel (Anguilla anguilla) macrophage-like primary cell cultures

The eel (Anguilla anguilla) has been identified as a vulnerable species with stocks dramatically declining over the past decade. In an effort to support the species from overfishing of wild stocks increased interest in eel aquaculture has been notable. In order to expand the scarce knowledge concerning the biology of this species significant research efforts are required in several fields of biology. The development of cell culture systems to study the immune response is a key step towards an increased understanding of the immune response and to develop resources to support further study in this threatened species. Macrophages are one of the most important effector cells of the innate immune system. The capacity to engulf pathogens and orchestrate the immune response relies on the existence of different surface receptors, such as scavenger receptors and toll-like receptors. We have developed and described an eel macrophage-like in vitro model and studied its functional and transcriptomic responses. Macrophage-like cells from both head kidney and purified peripheral blood leukocytes were obtained and phagocytic activity measured for different whole bacteria and yeast. Moreover, based on PAMP-PRR association the innate immune response of both head kidney and PBL derived macrophage-like cells was evaluated against different pathogen-associated molecular patterns (PAMPs). Results highlight that peptidoglycan stimulation strongly induces inflammatory mRNA expression reflected in the up-regulation of pro-inflammatory genes IL1β and IL18 in PBL derived cells whereas IL8 is upregulated in head kidney derived cells. Furthermore TLR2 mRNA abundance is regulated by all stimuli supporting a multifunctional role for this pathogen recognition receptor (PRR) in eel macrophage-like cells.

Integrated solutions for urban runoff pollution control in Brazilian metropolitan regions

One of the most important causes for poor water quality in urban rivers in Brazil is the low collection efficiency of the sewer system due to unforeseen interconnections with the stormwater drainage system. Since the beginning of the 20th century, Brazilian cities have adopted separate systems for sanitary sewers and stormwater runoff. Gradually these two systems became interconnected. A major challenge faced today by water managers in Brazil is to find efficient and low cost solutions to deal with this mixed system. The current situation poses an important threat to the improvement of the water quality in urban rivers and lakes. This article presents an evaluation of the water quality parameters and the diffuse pollution loads during rain events in the Pinheiros River, a tributary of the Tietê River in São Paulo. It also presents different types of integrated solutions for reducing the pollution impact of combined systems, based on the European experience in urban water management. An evaluation of their performance and a comparison with the separate system used in most Brazilian cities is also presented. The study is based on an extensive water quality monitoring program that was developed for a special investigation in the Pinheiros River and lasted 2.5 years. Samples were collected on a daily basis and water quality variables were analyzed on a daily, weekly or monthly basis. Two hundred water quality variables were monitored at 53 sampling points. During rain events, additional monitoring was carried out using an automated sampler. Pinheiros River is one of the most important rivers in the São Paulo Metropolitan Region and it is also a heavily polluted one.

A comparative epizootiologic study of the two fish-pathogenic serovars of Vibrio vulnificus biotype 2

Vibrio vulnificus biotype 2 is subdivided into two main serovars, serovar E, able to infect fish and humans, and serovar A, only virulent for fish. Serovar E emerged in 1976 as the causative agent of a haemorrhagic septicaemia (warm-water vibriosis) affecting eels cultured in brackish water. Serovar A emerged in 2000 in freshwater-cultured eels vaccinated against serovar E, causing warm-water vibriosis with fish showing a haemorrhagic intestine as the main differential sign. The aim of the present work was to compare the disease caused by both serovars in terms of transmission routes, portals of entry and host range. Results of bath, patch-contact and oral-anal challenges demonstrated that both serovars spread through water and infect healthy eels, serovar A entering mainly by the anus and serovar E by the gills. The course of the disease under laboratory conditions was similar for both serovars in terms of transmission and dependence of degree of virulence on water parameters (temperature and salinity). However, the decrease in degree of virulence in fresh water was significantly greater in serovar E than in serovar A. Finally, both serovars proved pathogenic for tilapia, sea bass and rainbow trout, but not for sea bream, with significant differences in degree of virulence only in rainbow trout. In conclusion, serovar A seems to represent a new antigenic form of V. vulnificus biotype 2 with an unusual portal of entry and is better adapted to fresh water than serovar E.

Role of the virulence plasmid pR99 and the metalloprotease Vvp in resistance of Vibrio vulnificus serovar E to eel innate immunity

Vibrio vulnificus biotype 2 serovar E (VSE) is a bacterial pathogen that produces a haemorrhagic septicaemia called vibriosis in eels. Its ability to grow in blood is conferred by a recently described virulence plasmid [Lee CT, Amaro C, Wu KM, Valiente E, Chang YF, Tsai SF, et al. A common virulence plasmid in biotype 2 Vibrio vulnificus and its dissemination aided by a conjugal plasmid. Journal of Bacteriology, submitted for publication.]. In this study, we analyzed the role of this plasmid together with the role played by the metalloprotease (Vvp) in the interaction between bacteria and eel innate immunity. To this end, we compared and statistically analyzed the differences in resistance to serum and mucus factors (complement, selected antimicrobial peptides, transferrin and lysozyme) and also to phagocytosis/opsonophagocytosis between one VSE strain and its derivatives: a plasmid-cured strain and a vvp-deficient mutant. The wild-type and the metalloprotease-deficient strains were resistant to both the bactericidal action of fresh serum and the phagocytosis and opsonophagocytosis by eel phagocytes, confirming that Vvp is not involved in resistance to eel innate immunity. In contrast, the cured strain was sensitive to both the bactericidal action of eel serum activated by the alternative pathway and phagocytosis/opsonophagocytosis. Since no plasmid-encoded ORF, with homology to known genes, is related to the resistance to innate immunity [Lee CT, Amaro C, Wu KM, Valiente E, Chang YF, Tsai SF, et al. A common virulence plasmid in biotype 2 Vibrio vulnificus and its dissemination aided by a conjugal plasmid. Journal of Bacteriology, submitted for publication.], this function could be codified by one or more new genes. Further studies are underway to characterize the plasmid-encoded system responsible for V. vulnificus resistance to the innate immune system of eels.

First description of non-motile Yersinia ruckeri serovar I strains causing disease in rainbow trout, Oncorhynchus mykiss (Walbaum), cultured in Spain

Yersinia ruckeri, the causal agent of enteric redmouth (ERM) disease, was isolated from epizootics that occurred in different Spanish rainbow trout, Oncorhynchus mykiss (Walbaum), farms in which vaccination against ERM had been performed. In all episodes, the most pronounced clinical signs exhibited by affected fish were severe haemorrhages in the mouth, eyes and around the vent. The isolates were identified as Y. ruckeri serovar I by 16S rRNA sequencing together with serological tests. They lacked motility and lipase activity and thus belonged to biotype 2, and were highly virulent for juvenile rainbow trout, both by intraperitoneal injection (from 3.1 x 10(2) to 6.3 x 10(3) cfu per fish) and bath challenge (5.1-7.3 x 10(6) cfu mL(-1)). This is the first description of Y. ruckeri serovar I biotype 2 causing disease in cultured trout in Spain vaccinated with commercial ERM vaccines. The occurrence of this emergent pathogen in Spanish continental aquaculture from its first isolation in 2001 to date is also documented.

Vibrio vulnificus serovar A: an emerging pathogen in European anguilliculture

The spread of the emerging pathogen Vibrio vulnificus biotype 2 serovar A in Danish anguilliculture is reported. Serovar A was originally isolated in a Spanish eel farm in 2000 and occurred in Denmark in the summer of 2004, affecting eels of 5-10 g body weight cultured in fresh water. The Danish eels showed clinical signs different from those reported for Spanish eels, such as severe haemorrhages in the head and gill region with necrosis of the soft tissues. Danish isolates were biochemically and serologically identical to Spanish serovar A strains and also highly virulent for eels by both intraperitoneal injection and immersion challenges. Vaccination with Vulnivaccine, a vaccine against V. vulnificus serovar E, cross-protected eels against serovar A. The LD(50) for experimentally infected vaccinated animals was significantly higher than for non-vaccinated animals.

Efficacy of a bivalent vaccine against eel diseases caused by Vibrio vulnificus after its administration by four different routes

Vulnivaccine, a vaccine against vibriosis caused by Vibrio vulnificus serovar E (formerly biotype 2), confers acceptable levels of protection to eels after its administration by prolonged immersion in three doses. Recently, a new pathogenic serovar, named serovar A, has been isolated from vaccinated eels in a Spanish freshwater eel farm. The main objective of this work was to design a bivalent vaccine, and to study its effectiveness against the two pathogenic serovars. With this aim, eels weighing around 20 g were immunised with the bivalent vaccine by oral and anal intubation, intraperitoneal injection (i.p.) and prolonged immersion. The overall results indicated that: (i) the new vaccine delivered by oral and anal intubation induced protection levels higher than 80%, to that achieved after i.p. vaccination; (ii) oral and anal vaccination induced a significant systemic and mucosal immune response; (iii) the protection after vaccination by whichever routes was related to antibody titres in plasma; (iv) mucosal and systemic compartments showed different kinetics of antibody production; (v) evidence for passive transfer of antibodies from plasma to gut mucus were found after i.p. and anal vaccination, and finally, (vi) vaccination did not enhance the production of lysozyme, in plasma or mucus. In conclusion, this new vaccine is effective in protecting eels against vibriosis caused by the two eel-pathogenic serovars of V. vulnificus, the oral delivery system is a promising way which may be used in intensive culture facilities during the whole growth period of eels.

The kinetics of antibody production in mucus and serum of European eel (Anguilla anguilla L.) after vaccination against Vibrio vulnificus: development of a new method for antibody quantification in skin mucus

Vibrio vulnificus serovar E, a bacterial pathogen for eels cultured in intensive systems, is transmitted through water and enters into new hosts mainly via gills. The main objective of this work was to study the kinetics of antibody production to V. vulnificus in serum and mucus and their relationship with protection after vaccination. To quantify local mucus antibodies, a new "in situ" dot blot immunoassay using image analysis has been developed. This assay was applied to measure antibody production in the skin zone next to the gills. We found that (i) the immune response in mucus was faster (peak at days 3-4) and shorter in duration (titres significantly elevated up to day 5 and 11 for skin zone next to the gills and for general cutaneous mucus, respectively) than in serum (peak at day 7; titres significantly elevated for more than 25 days); (ii) the exposure of vaccinated eels with basal levels of local antibodies to sub-lethal dose of the pathogen stimulated a more lasting secreted antibody production (for more than 14 days); (iii) protection and antibody levels in serum were clearly correlated, and (iv) immunised eels with basal levels of serum antibodies and maximal levels of local antibodies were partially protected.

Transmission to eels, portals of entry, and putative reservoirs of Vibrio vulnificus serovar E (biotype 2)

Vibrio vulnificus serovar E (formerly biotype 2) is the etiologic agent that is responsible for the main infectious disease affecting farmed eels. Although the pathogen can theoretically use water as a vehicle for disease transmission, it has not been isolated from tank water during epizootics to date. In this work, the mode of transmission of the disease to healthy eels, the portals of entry of the pathogen into fish, and their putative reservoirs have been investigated by means of laboratory and field experiments. Results of the experiments of direct and indirect host-to-host transmission, patch contact challenges, and oral-anal intubations suggest that water is the prime vehicle for disease transmission and that gills are the main portals of entry into the eel body. The pathogen mixed with food can also come into the fish through the gastrointestinal tract and develop the disease. These conclusions were supported by field data obtained during a natural outbreak in which we were able to isolate this microorganism from tank water for the first time. The examination of some survivors from experimental infections by indirect immunofluorescence and scanning electron microscopy showed that V. vulnificus serovar E formed a biofilm-like structure on the eel skin surface. In vitro assays demonstrated that the ability of the pathogen to colonize both hydrophilic and hydrophobic surfaces was inhibited by glucose. The capacity to form biofilms on eel surface could constitute a strategy for surviving between epizootics or outbreaks, and coated survivors could act as reservoirs for the disease.

Field testing of a vaccine against eel diseases caused by Vibrio vulnificus

The field results of a vaccination programme against Vibrio vulnificus serovar E (biotype 2) in a Spanish eel farm are reported. A total of 9.5 million glass eels were vaccinated from January 1998 to March 2000 by prolonged immersion followed by 2 subsequent reimmunisations after 12 to 14 and 24 to 28 d, respectively. The acquired protection and the immune response against serovar E were estimated over a period of 6 mo after vaccination. A similar vaccination schedule was conducted with elvers in a Danish eel farm. In this case, the acquired protection and the immune response against serovar E and the new eel-pathogenic serovars, recently described in Denmark, were evaluated over a short term. The overall results show that the vaccine against V. vulnificus serovar E induces a satisfactory protective immunity during the main growth period of eels (around 6 mo) with a relative percentage survival of 62 to 86% and protects them against the new eel-pathogenic serovars. Vaccination of eels by immersion seems to be the best strategy to prevent diseases caused by V. vulnificus.

Effectiveness of different vaccine formulations against vibriosis caused by Vibrio vulnificus serovar E (biotype 2) in European eels Anguilla anguilla

Vibriosis due to Vibrio vulnificus serovar E (biotype 2) is one of the main causes of mortality in European eels cultured in Europe. The main objective of this study was to develop a vaccine and a vaccination procedure against this pathogen. With this aim, we tested several vaccine formulations (inactivated whole-cells with and without toxoids--inactivated extracellular products--from capsulated and uncapsulated strains, attenuated live vaccines and purified lipopolysaccharide [LPS]) on eels maintained under controlled laboratory conditions using different delivery routes (injection and immersion). To study the immune response we estimated antibody titers and bactericidal/bacteriostatic activity in mucus and serum. To evaluate protection, we calculated the relative percent survival (RPS) after intraperitoneal (i.p.) injection and bath challenge of the pathogen. The overall results indicate that: (1) capsular antigens seem to be essential for protective immunization; (2) vaccines confer the highest protection when administered by i.p. injection; (3) booster is needed to achieve good protection by immersion; (4) enriching the vaccine with toxoids enhances protection to optimal levels (RPS values around 70 to 100%, depending on the delivery route); and (5) the protective effect in serum and mucus depends on the route of administration and seems to be related to the production of specific antibodies.

An indirect immunofluorescent antibody technique for detection and enumeration of Vibrio vulnificus serovar E (biotype 2): development and applications

The applications of an indirect fluorescent antibody technique (IFAT), developed to detect and enumerate the pathogenic bacterium Vibrio vulnificus serovar E from water and clinical samples, are described. This technique proved accurate for detecting V. vulnificus, even under starvation conditions and in the non-culturable state, and could differentiate this species from other bacteria which share the same habitats. The IFAT was successfully used to diagnose vibriosis from naturally- and artificially-infected eels. The overall data suggest that applying this technique properly in environmental and epidemiological/epizootiological studies could significantly increase our knowledge of this bacterium.

Evidence that water transmits the disease caused by the fish pathogen Photobacterium damselae subsp. damselae

The transmission through water of the disease caused by the fish pathogen, Photobacterium damselae subsp. damselae, as well as the role of the skin mucus in the initial steps of the infection, have been studied. All tested strains resisted the bactericidal activity of the mucus and showed an ability to adhere to it, but only those virulent by the intraperitoneal route were infective through water. Moribund fishes showed the typical signs of the disease: haemorrhaged areas on the body surface and ulcerative lesions with mucus degradation. These results suggest that the pathogen can be transmitted to fish through water and use the skin as a portal of entry.

Ferric-reductase activities in Vibrio vulnificus biotypes 1 and 2

In this paper, the ferric-reductase activities of Vibrio vulnificus were investigated. This species comprises two biotypes pathogenic for humans and eels that are able to express different mechanisms for iron acquisition. All strains of both biotypes used in this study were able to reduce ferric citrate, irrespective of the iron levels in the growth medium. Some variation in the degree of reduction was observed among the strains, with the highest values corresponding to one acapsulated environmental strain of biotype 1. When cell fractions were tested, only those from periplasm and cytoplasm showed reductase activity whereas no activity was detected in membranes. Low temperatures inhibited these activities in both whole cells and cell fractions. At least six bands with ferric-reductase activity were identified in all strains using native polyacrylamide gels. These data demonstrate that the two biotypes of V. vulnificus produce similar ferric-reductases mainly located in the periplasm and cytoplasm and these could be involved in iron acquisition.

Isolation of Vibrio vulnificus serovar E from aquatic habitats in Taiwan

The existence of strains of Vibrio vulnificus serovar E that are avirulent for eels is reported in this work. These isolates were recovered from water and oysters and differed from eel virulent strains in (i) fermentation and utilization of mannitol, (ii) ribotyping after HindIII digestion, and (iii) susceptibility to eel serum. Lipopolysaccharide of these strains lacked the highest molecular weight immunoreactive bands, which are probably involved in serum resistance.

Effects of salinity and temperature on long-term survival of the eel pathogen Vibrio vulnificus biotype 2 (serovar E)

Vibrio vulnificus biotype 2 (serovar E) is a primary eel pathogen. In this study, we performed long-term survival experiments to investigate whether the aquatic ecosystem can be a reservoir for this bacterium. We have used microcosms containing water of different salinities (ranging from 0.3 to 3.8%) maintained at three temperatures (12, 25, and 30 degrees C). Temperature and salinity significantly affected long-term survival: (i) the optimal salinity for survival was 1.5%; (ii) lower salinities reduced survival, although they were nonlethal; and (ii) the optimal temperature for survival was dependent on the salinity (25 degrees C for microcosms at 0.3 and 0.5% and 12 degrees C for microcosms at 1.5 to 3.8%). In the absence of salts, culturability dropped to zero in a few days, without evidence of cellular lysis. Under optimal conditions of salinity and temperature, the bacterium was able to survive in the free-living form for at least 3 years. The presence of a capsule on the bacterial cell seemed to confer an advantage, since the long-term survival rate of opaque variants was significantly higher than that of translucent ones. Long-term-starved cells maintained their infectivity for eels (as determined by both intraperitoneal and immersion challenges) and mice. Examination under the microscope showed that (i) the capsule was maintained, (ii) the cell size decreased, (iii) the rod shape changed to coccuslike along the time of starvation, and (iv) membrane vesicles and extracellular material were occasionally produced. In conclusion, V. vulnificus biotype 2 follows a survival strategy similar to that of biotype 1 of this species in response to starvation conditions in water. Moreover, the aquatic ecosystem is one of its reservoirs.

Comparative study of biological properties and electrophoretic characteristics of lipopolysaccharide from eel-virulent and eel-A virulent Vibrio vulnificus strains

In Vibrio vulnificus, virulence for eels is associated with serovar E strains. In this study, we investigated some biological properties of purified lipopolysaccharides (LPSs) from serovar E and non-serovar E strains. Purified LPSs retained their O-polysaccharidic side chains and did not show any differences that could be related to host specificity, except for serological differences.

Isolation and characterization of Vibrio parahaemolyticus causing infection in Iberian toothcarp Aphanius iberus

High mortality among laboratory cultured Iberian toothcarp Aphanius iberus occurred in February 1997 in Valencia (Spain). The main signs of the disease were external haemorrhage and tail rot. Bacteria isolated from internal organs of infected fish were biochemically homogeneous and identified as Vibrio parahaemolyticus. The bacteria were haemolytic against erythrocytes from eel Anguilla anguilla, amberjack Seriola dumerili, toothcarp A. iberus and humans, and were Kanagawa-phenomenon-negative. Infectivity tests showed that the virulence for A. iberus was dependent on salinity. Finally, all strains were virulent for amberjack and eel.

Survival of fish-virulent strains of Photobacterium damselae subsp. damselae in seawater under starvation conditions

The survival of fish-virulent strains of Photobacterium damselae subsp. damselae in seawater microcosms, with and without sediment, was investigated. The strains survived as culturable bacteria at 14 and 22 degrees C for at least 1 year, and infectivity for fish was maintained. At 5 degrees C, cells lost culturability on solid media, but this was recovered when the temperature was increased to 22 degrees C. Finally, morphological changes in the bacterium (rod to coccus), and production of vesicles and extracellular material were observed during the time of starvation. The overall results suggest that seawater and sediment can act as reservoirs for these virulent strains.

Isolation of a hemin and hemoglobin binding outer membrane protein of Vibrio vulnificus biotype 2 (serogroup E)

The eel pathogen Vibrio vulnificus biotype 2 (serogroup E) is able to use hemin (Hm) or hemoglobin (Hb) as the sole iron source for growth in vitro and in vivo. The mechanism of heme-iron acquisition in this bacterium requires a direct interaction through binding sites on the bacterial surface (constitutive outer membrane proteins). Using affinity chromatography techniques, a unique protein of around 36.5 kDa was isolated from cell envelopes of E86 strain regardless of the affinity ligand used, hemoglobin or hemin. This protein was purified from both iron-enriched and iron-restricted grown cells. These results support the hypothesis that in this pathogen Hm- and Hb-iron acquisition is mediated by a common protein receptor which recognizes the heme prosthetic group of Hb.

The lipopolysaccharide O side chain of Vibrio vulnificus serogroup E is a virulence determinant for eels

Vibrio vulnificus is a gram-negative bacterium capable of producing septicemic infections in eels and immunocompromised humans. Two biotypes are classically recognized, with the virulence for eels being specific to strains belonging to biotype 2, which constitutes a homogeneous lipopolysaccharide (LPS)-based O serogroup (which we have designated serogroup E). In the present study we demonstrated that the O side chain of this LPS determines the selective virulence of biotype 2 for eels: (i) biotype 1 strains (which do not belong to serogroup E) are destroyed by the bactericidal action of nonimmune eel serum (NIS) through activation of the alternative pathway of complement, (ii) biotype 2 strains (of serogroup E) are resistant to NIS, and (iii) rough mutants of biotype 2 lacking the O polysaccharide side chain are sensitive to NIS and avirulent for eels.

Phenotypic and genotypic characterization of Vibrio vulnificus: proposal for the substitution of the subspecific taxon biotype for serovar

The classification of Vibrio vulnificus strains into two biotypes has been maintained on the basis of phenotypic properties and eel virulence. Biotype 2 is virulent for eels, negative for the indole reaction, and serologically homogeneous (serogroup E), whereas strains of biotype 1 are avirulent, indole positive, and serologically heterogeneous. In the present study, we phenotypically and genotypically characterized 21 V. vulnificus isolates, recovered mainly from northern Europe, by comparing them with reference strains of both biotypes to look for new isolates of biotype 2. The results of this work revealed that the majority of isolates virulent for eels presented phenotypic traits previously considered characteristics of biotype 2 and specific ribotypes with HindIII. However, among the new isolates we found (i) a serogroup E strain virulent for eels but indole positive and (ii) one isolate not belonging to serogroup E but pathogenic for eels. Since no biochemical test for specific serogroup can with certainty be associated with eel virulence, we propose to classify V. vulnificus strains into serovars instead of biotypes. Thus, we suggest serovar E as the denomination of those strains previously classified as biotype 2. Finally, the occurrence of serogroup E in eels cultured in Norway and Sweden, as well as from human infections and shrimp, has been demonstrated.

An enzyme-linked immunosorbent assay for detection of Vibrio vulnificus biotype 2: development and field studies

Vibrio vulnificus biotype 2 is a primary eel pathogen which constitutes a lipopolysaccharide (LPS)-based homogeneous O serogroup within the species. In the present work, we have developed an enzyme-linked immunosorbent assay (ELISA) based on the specificity of LPS for the detection of this pathogen. The ELISA specificity was confirmed after testing 36 biotype 2 strains from laboratory cultures and environmental samples, 31 clinical and environmental biotype 1 isolates, and several strains of Vibrio, Aeromonas, and Yersinia species, including the fish pathogens V. anguillarum, V. furnissii, A. hydrophila, and Y. ruckerii. The detection limits for biotype 2 cells were around 10(4) to 10(5) cells/well, and the immunoassay was also able to detect cells in the nonculturable state. Artificially infected eels and environmental samples were analyzed, and the immunodetection was confirmed by cultural methods (isolation on selective and nonselective media before and after broth enrichment). With this methodology, V. vulnificus biotype 2 was successfully detected in infected eels and asymptomatic carriers, which suggests that eels can act as a reservoir for this pathogen.

High affinity iron-uptake systems in Vibrio damsela: role in the acquisition of iron from transferrin

In this work, the high affinity iron-acquisition systems displayed by virulent and avirulent strains of Vibrio damsela have been investigated. This species is an autochthonous member of marine ecosystems that can behave as an opportunistic pathogen for fish and mammals. All strains tested (i) were able to grow under the restricted conditions imposed by the iron chelators transferrin (Tf) and EDDHA, (ii) secreted siderophores of hydroxamic type, other than aerobactin and desferal, that were able to stimulate the growth of the auxotroph mutant Arthrobacter flavescens JG9, and (iii) expressed common iron-regulated outer membrane proteins (IROMPs). No change in LPS patterns was observed in response to iron restriction. Results from the assays with transferrin suggest that these siderophores could be utilized to sequester iron from Tf, a protein for which no surface receptor was detected in any strain. In summary, the overall data demonstrate that V. damsela expresses siderophore-mediated iron-uptake systems. These systems are probably involved in the survival of the species in the different environments that it can colonize, i.e. water and several vertebrate hosts.

Utilization of hemin and hemoglobin by Vibrio vulnificus biotype 2

The eel pathogen Vibrio vulnificus biotype 2 is able to use hemoglobin (Hb) and hemin (Hm) to reverse iron limitation. In this stud, the adjuvant effect of both compounds on eel pathogenicity has been evaluated and confirmed. Further, we have studied the heme-iron acquisition mechanism displayed by this bacterium. Whole cells were capable of binding Hb and Hm, independently of (i) iron levels in growth medium and (ii) the presence of polysaccharide capsules on bacterial surface. The Hb- and Hm-binding capacity was retained by the outer membrane protein (OMP) fraction and was abolished after proteolytic digestion of OMP samples. Western blotting (immunoblotting) of denatured OMPs revealed that two major protein bands of 36 and 32 kDa were involved in both Hm and Hb binding. The expression of these proteins was not affected by iron levels. In addition, V. vulnificus biotype 2 produced extracellular proteases, not regulated by iron, that were active against native Hb. In conclusion, the overall data suggest that the eel pathogen V. vulnificus biotype 2 can obtain iron by means of a mechanism which involves a direct interaction between the heme moiety and constitutive OMPs.

Toxic and enzymatic activities of Vibrio vulnificus biotype 2 with respect to host specificity

In this work, the enzymatic activities of selected strains of biotypes 1 and 2 of Vabrio vulnificus were analyzed by using conventional methods and the API ZYM system. The toxic activities of extracellular products (ECPs) were further evaluated by in vitro and in vivo experiments. The ECPs of both biotypes (i) showed high-level hydrolytic activities, (ii) displayed cytotoxicity for fish cell lines, and (iii) were lethal for eels. Exotoxins seem to be proteinaceous since heat treatment of ECP samples destroyed their toxicity. Only biotype 2 strains were virulent for cels, suggesting that host specificity must be related to differences in cell surface properties. Infectivity trials with other fish species also revealed that only biotype 2 strains were virulent.

Vibrio vulnificus biotype 2, pathogenic for eels, is also an opportunistic pathogen for humans

We report that the eel pathogen Vibrio vulnificus biotype 2 is also an opportunistic pathogen for humans. Results from a detailed comparative study using reference strains of both biotypes revealed that the clinical strain ATCC 33817, originally isolated from a human leg wound and classified as V. vulnificus (no reference on its biotype is noted), belongs to biotype 2 of the species. As a biotype 2 strain, it is negative for indole and pathogenic for eels and mice, harbors two plasmids of high MrS, and belongs to serogroup E, recently proposed as characteristic of biotype 2 strains. In consequence, appropriate measures must be taken by consumers, particularly by those running a health risk, and by fish farmers, above all when manipulating eels during epizootic outbreaks.

Phenotypic characterization of Vibrio vulnificus biotype 2, a lipopolysaccharide-based homogeneous O serogroup within Vibrio vulnificus

In this study, we have reevaluated the taxonomic position of biotype 2 of Vibrio vulnificus. For this purpose, we have biochemically and serologically characterized 83 biotype 2 strains from diseased eels, comparing them with 17 biotype 1 strains from different sources. Selected strains were also molecularly analyzed and tested for eel and mouse pathogenicity. Results have shown that biotype 2 (i) is biochemically homogeneous, indole production being the main trait that distinguishes it from biotype 1, (ii) presents small variations in DNA restriction profiles and outer membrane protein patterns, some proteins being immunologically related to outer membrane proteins from biotype 1, (iii) expresses a common lipopolysaccharide (LPS) profile, which is immunologically identical among strains and distinct from that of LPS of tested biotype 1 strains, and (iv) contains at least two high-Mr plasmids. Regarding host range, we have confirmed that both biotypes are pathogenic for mice but only biotype 2 is pathogenic for eels. On the basis of these data, we propose that biotype 2 of V. vulnificus constitutes an LPS-based O serogroup which is phenotypically homogeneous and pathogenic for eels. In this article, the serogroup is designated serogroup E (for eels).

Siderophore-mediated iron acquisition mechanisms in Vibrio vulnificus biotype 2

Vibrio vulnificus biotype 2 is a primary pathogen for eels and, as has recently been suggested, an opportunistic pathogen for humans. In this study we have investigated the ability of V. vulnificus biotype 2 to obtain iron by siderophore-mediated mechanisms and evaluated the importance of free iron in vibriosis. The virulence degree for eels was dependent on iron availability from host fluids, as was revealed by a reduction in the 50% lethal dose for iron-overloaded eels. This biotype produced both phenolate- and hydroxamate-type siderophores of an unknown nature and two new outer membrane proteins of around 84 and 72 kDa in response to iron starvation. No alterations in lipopolysaccharide patterns were detected in response to iron stress. Finally, our data suggest that V. vulnificus biotype 2 uses the hydroxamate-type siderophore for removal of iron from transferrin rather than relying on a receptor for this iron-binding protein.

Effect of low temperature on starvation-survival of the eel pathogen Vibrio vulnificus biotype 2

At present, no reports exist on the isolation of the eel pathogen Vibrio vulnificus biotype 2 from water samples. Nevertheless, it has recently been demonstrated that this biotype can use water as a route of infection. In the present study, the survival of this pathogen in artificial seawater (ASW) microcosms at different temperatures (25 and 5 degrees C) was investigated during a 50-day period, with biotype 1 as a control, V. vulnificus biotype 2 was able to survive in the culturable state in ASW at 25 degrees C in the free-living form, at least for 50 days, entering into the nonculturable state when exposed to low temperature. In this state, this microorganism survived with reduced rates of activity, showing marked changes in size and morphology. The rate at which cells became nonculturable was dependent on their physiological age. The capsule seems not to be necessary for the survival of biotype 2 in aquatic environments as a free-living organism. Culturability remained the highest on modified salt water yeast extract agar, which is closer in salt and nutrient composition to ASW than heart infusion agar. Biotype 2 cells recovered culturability on solid media after an increase of incubation temperature from 5 to 25 degrees C. Culturable cells of this bacterium maintained infectivity for either eel or mice, while dormant cells seemed to lose their virulence. The former finding suggests that the aquatic environment is a reservoir and vehicle of transmission of this pathogen.

Evidence that water transmits Vibrio vulnificus biotype 2 infections to eels

Vibrio vulnificus biotype 2 is classically considered an obligate eel pathogen. However, it has recently been associated with one human septicemic case. In this paper, the opportunistic behavior of this pathogen is discussed. The bacterium can survive alone in brackish water or attached to eel surfaces for at least 14 days. It is able to spread through water and infect healthy eels by using skin as a portal of entry. These results suggest that water and infected eels may act as reservoirs of infection. A capsule seems to be essential for waterborne infectivity, which would explain why cells recovered from naturally diseased eels give rise to pure cultures of opaque colonies. The spread of the disease is dependent on temperature and water salinity, thus suggesting a method to reduce the risk of epizootics and that of infection for humans.

Role of iron in the pathogenicity of Vibrio damsela for fish and mammals

The ability to obtain iron of 14 isolates of Vibrio damsela with different degrees of virulence for mice and turbot (Scophthalmus maximus) has been evaluated in artificial and natural iron-restricted environments. All strains were capable of utilizing haemoglobin (Hb) and ferric ammonium citrate (FAC) as the sole iron sources in vitro. However, only virulent V. damsela strains were able to resist the bacteriostatic and bactericidal effects of human and turbot sera, their growth being enhanced by the addition of Hb and FAC. The inhibitory effect of these sera on the growth of the non-pathogenic strain (ATCC 35083), however, was reversed by heat treatment (56 degrees C for 60 min). The role of iron-availability on the virulence was investigated in iron-overloaded animals. The iron-treatment before the infection resulted in a significant reduction in the LD50 of virulent strains. This fact demonstrates a positive correlation between iron availability in host fluids and degree of virulence in the species Vibrio damsela.

O-serogrouping and surface components of Aeromonas hydrophila and Aeromonas jandaei pathogenic for eels

The relationship between virulence, O-serogroup, and some cell-surface features (self-pelleting [SP] and precipitation after boiling [PAB], profile of lipopolysaccharides [LPSs] and outer membrane proteins [OMPs]) was investigated in strains of the pathogenic species Aeromonas hydrophila and A. jandaei isolated from eels. Virulent strains of A. hydrophila reacted mostly with O:19 antiserum, and those of A. jandaei reacted with O:4, O:11, O:15 and O:29 antisera (Guinée and Jansen system). Regarding the PAB and LPS profiles two groups could be distinguished; (i) five PAB+ strains of serotype O:19 that possessed a homogeneous O polysaccharide side chain and (ii) thirteen PAB- strains antigenically diverse that either exhibited a heterogeneous side chain or were side chain deficient. A major 50 kDa protein was only found in the PAB+ strains, whereas major OMPs detected in PAB- strains ranged from 33 to 45 kDa irrespective of the species. Epizootic eel isolates of A. hydrophila belong to serotype O:19 and share cell-surface features with the Aeromonas highly virulent for other hosts. In contrast, epizootic A. jandaei isolates were antigenically diverse. These findings reinforce the importance of an O-serotype as an epidemiological marker in motile Aeromonas strains pathogenic for eels.

Role of iron, capsule, and toxins in the pathogenicity of Vibrio vulnificus biotype 2 for mice

The virulence mechanisms of Vibrio vulnificus biotype 2 have been studied and compared with those of biotype 1 in mice as the experimental animals. Biotype 2 isolates from European eels were as virulent for mice as biotype 1 strains (50% lethal dose, about 10(5) CFU per mouse); a septicemic infection developed in less than 24 h. These strains had several properties in common with biotype 1 organisms including capsule expression, uptake of various iron sources, and production of exoproteins, whose role in mouse virulence has been demonstrated. We also discuss the implication of biotype 2 strains in human infections.

Presence of a capsule in Vibrio vulnificus biotype 2 and its relationship to virulence for eels

Strains of Vibrio vulnificus biotype 2, isolated from internal organs of diseased European eels as pure cultures of opaque cells, together with some reference strains from Japanese eels, were used in this study. Spontaneous translucent-phase variants were obtained from the corresponding parent strains and compared for a variety of phenotypic traits related to virulence for eels. The rate of colony dissociation from opaque to translucent cells was higher (around 10(-2)) than that observed for translucent to opaque cells (10(-3) to 10(-4)). Electron microscopy with ruthenium red revealed the presence of a capsule of variable thickness on opaque cells, whereas translucent-type colonies had no observable capsular materials. No differences in plasmid profiles were detected between the two cell types so that plasmids do not seem to be implicated in the mechanism of phase shift of biotype 2 strains. No apparent difference in outer membrane protein and lipopolysaccharide patterns could be observed between the cell types. Both isogenic morphotypes were able to grow in eel serum and minimal medium supplemented with ethylenediamine di(O-hydroxyphenyl-acetic acid) or transferrin. Therefore, the presence of capsule was not required for the acquisition of iron from iron chelators or for resistance to serum bactericidal action. Both morphotypes were highly virulent for elvers, although the 50% lethal dose for translucent cells was higher than that for the corresponding opaque cells. The latter observation, together with the overall data, suggests that the production of capsular materials by biotype 2 of V. vulnificus is not essential for the development of vibriosis in eels, at least when cells are injected intraperitoneally.