The effect of suspending solution supplemented with marine cations on the oxidation of Biolog GN MicroPlate substrates by Vibrionaceae bacteria

Bacteria belonging to the family Vibrionaceae were suspended using saline and a solution prepared from a marine-cations supplement. The effect of this on the profile of oxidized substrates obtained when using Biolog GN MicroPlates was investigated. Thirty-nine species belonging to the genera Aeromonas, Listonella, Photobacterium, and Vibrio were studied. Of the strains studied, species of Listonella, Photobacterium, and Vibrio could be expected to benefit from a marine-cations supplement that contained Na+, K+, and Mg2+. Bacteria that are not of marine origin are usually suspended in normal saline. Of the 39 species examined, 9 were not included in the Biolog data base and were not identified. Of the 30 remaining species, 50% were identified correctly using either of the suspending solutions. A further 20% were correctly identified only when suspended in saline. Three species, or 10%, were correctly identified only after suspension in the marine-cations supplemented solution. The remaining 20% of species were not correctly identified by either method. Generally, more substrates were oxidized when the bacteria had been suspended in the more complex salts solution. Usually, when identifications were incorrect, the use of the marine-cations supplemented suspending solution had resulted in many more substrates being oxidized. Based on these results, it would be preferable to use saline to suspend the cells when using Biolog for identification of species of Vibrionaceae. A salts solution containing a marine-cations supplement would be preferable for environmental studies where the objective is to determine profiles of substrates that the bacteria have the potential to oxidize. If identifications are done using marine-cations supplemented suspending solution, it would be advisable to include reference cultures to determine the effect of the supplement. Of the Vibrio and Listonella species associated with human clinical specimens, 8 out of the 11 studied were identified correctly when either of the suspending solutions was used.

A new approach to separate the genus Photobacterium from Vibrio with RFLP patterns by HhaI digestion of PCR-amplified 16S rDNA

A new approach to separate members of the genus Photobacterium from the genus Vibrio with RFLP (Restriction Fragment Length Polymorphism) patterns by HhaI digestion of PCR-amplified 16S rDNA was developed in the present study. It was clearly shown that these patterns of the genus Photobacterium were unique and distinguishable from Vibrio species. This method is very simple and does not need other supporting procedures, such as Southern transfer and probe hybridization. It can be applied not only to luminous species, but also to non-luminous Photobacterium spp. This result promises a rapid tool to distinguish the genus Photobacterium from Vibrio and should be useful in routine identification system.

A comparison of strategies for the detection and recovery of Vibrio vulnificus from marine samples of the western Mediterranean coast

We have compared the effectiveness of culture-based methods and a DNA-based method for the detection, of Vibrio vulnificus from a seawater and three types of shellfish collected from the costal waters of Valencia, Spain. For culture-based method, we used two selective media, thiosulphate-citrate-salts-sucrose (TCBS), and cellobiose-polymyxin B-colistin (CPC) agars with and without previous enrichment in alkaline-saline-peptone-water (APWS). Presumptive colonies were confirmed as V. vulnificus by the polymerase chain reaction (PCR) using previously described 23S rRNA V. vulficus-specific sequences as primers (Dvu 9V and Dvu 45R). Direct detection was accomplished by a nested-PCR procedure developed for environmental samples, with the above mentioned primers for the second amplification. Of 32 seawater samples, only one yielded positive results by direct detection by PCR, whereas five were positive by culture methods. Of the 32 bivalve samples, two were positive by PCR and five by culture methods. From a total of 675 presumptive colonies selected on the two media, only 48 (20 from seawater and 28 from bivalves) were confirmed as V. vulnificus by PCR. Forty-six V. vulnificus isolates were obtained after enrichment and only two after direct inoculation of CPC. Except for one sampling, positive results by direct detection did not correlate with confirmed strains obtained from culture media. API 20E profiles were recorded for all isolates previously identified as V. vulnificus, revealing that around 20% of the strains were sucrose-positive. For our samples, the best strategy consisted in the combination of culture based methods (3 h enrichment in APWs at 40 degrees C followed by CPC at the same temperature) and DNA-based procedures (specific PCR amplification of the presumptive colonies with primers Dvu 9V and Dvu 45 R), which allowed the detection and accurate identification of V. vulnificus in less than 48h. This is the first report on the detection of cells of V. vulnificus naturally present in seawater and edible shellfish in the Spanish Mediterranean coast.

Clinical infections of Vibrio vulnificus: a case report and review of the literature

Vibrio vulnificus is a marine Gram-negative bacillus that is recognized as a cause of fulminant primary septicemia and wound infections. One of the most common bacteria in seawater, V. vulnificus is concentrated in ocean filter feeders (e.g., oysters and clams). Primary septicemia can occur in patients, typically with underlying liver disease, who have acquired the organism through the gastrointestinal tract after recent consumption of raw shellfish. Characterized by fevers, chills, and bullous skin lesions, V. vulnificus septicemia is associated with a mortality greater than 50%. With septic shock, mortality approaches 100%. Wound infections are seen after injury to the skin in a marine environment or from exposure of preexisting wounds to seawater. Because of the high morbidity and mortality associated with V. vulnificus infections, effective treatment includes preventive measures to educate high-risk individuals, early search for and recognition of the disease, aggressive antibiotic therapy, supportive care, and, in the case of wound infections, aggressive debridement. Review of this subject was prompted by a case of V. vulnificus primary septicemia and fulminant septic shock in a patient with the unusual presentation of pain in the lower extremities.

[Comparison of outer membrane protein profiles of Vibrio sp]

The outer membrane protein (OMP) profiles of 32 Vibrio type strains have been compared. The major OMP profiles of different Vibrio species had a considerable heterogenecity. Most of the strains had 3-7 major OMPs, with molecular masses ranging between 91,000 and 14,000. Many strains had common major OMPs such as 54,000, 43,000 and 27,000. However, no common major OMPs in all Vibrio type strains had been found.

Vibrio diabolicus sp. nov., a new polysaccharide-secreting organism isolated from a deep-sea hydrothermal vent polychaete annelid, Alvinella pompejana

A deep-sea, facultatively anaerobic, heterotrophic, mesophilic new organism was isolated from the polychaete annelid Alvinella pompejana collected from a deep-sea hydrothermal field in the East Pacific Rise. On the basis of phenotypic characteristics, phylogenetic analyses, and DNA-DNA relatedness, this organism was identified as a new species of the genus Vibrio, for which the name Vibrio diabolicus is proposed. In batch cultures in the presence of glucose, this organism produced an innovative exopolysaccharide. This polymer had high contents of both uronic acids and hexosamines and was similar to other polysaccharides with interesting biological activities.

Vibrio furnissii isolated from humans in Peru: a possible human pathogen?

During a cholera surveillance programme, Vibrio furnissii was isolated in late January and early February 1994 from stool samples collected from 14 persons of whom six had diarrhoea. The remaining eight persons were healthy family members or neighbours to cholera cases. No common source of infection was found. Strains isolated from stool samples each showed typical biochemical reactions of V. furnissii including gas production. Each isolate, except one, agglutinated O-antisera yielding a total of eight different serotypes. Most isolates were sensitive to 10 antibiotics tested, except to ampicillin and the vibriostatic agent O/129 (10 micrograms). Eight of 14 (57%) strains carried plasmids in the size range 2.6-88 kb, however, no correlation was found between antibiotic susceptibility patterns and plasmid content. Altogether, seven closely related HindIII ribotypes were observed among the 14 V. furnissii isolates studied. V. furnissii strains isolated from family members and other persons living close together often showed different ribotypes suggesting that the isolation was not associated with neighbourhood. Serotyping, plasmid profiling and ribotyping revealed a high strain diversity within V. furnissii, however, the importance of V. furnissii as an enteric pathogen remains to be elucidated.

Vibrio damsela associated with diseased fish in Denmark

A total of 26 Vibrio damsela strains were isolated in Denmark. Fifteen strains were isolated from the head kidney of rainbow trout (Oncorhynchus mykiss) in aquaculture, eight were from organs of two stingrays (Dasyatis pastinaca) held in captivity, two were from organs and pathological material of a nurse shark (Orectolobus ornatus) held in captivity, and one was from the water in the aquarium where the rays and shark were kept. This is the first report on the isolation of V. damsela in Denmark and the first report on this organism associated with diseased farmed rainbow trout. Ecological and epizootiological aspects of the observation are discussed on the basis of phenotypic and genotypic properties of the isolated strains.

Isolation and characterization of Vibrio carchariae, a causative agent of gastroenteritis in the groupers, Epinephelus coioides

An outbreak of serious mortality among the cultured groupers Epinephelus coioides, characterized by a swollen intestine containing yellow fluid, occurred in the summer of 1993 in Taiwan. A motile strain EmI82KL was isolated from the intestinal yellow fluid of the moribund groupers with tryptic soy agar supplemented with 2% NaCl and/or thiosulfate citrate bile salt sucrose agar. This strain was characterized and identified as Vibrio carchariae and was susceptible to chloramphenicol, doxycycline-HCl, nalidixic acid, oxolinic acid, oxytetracycline, and sulfonamide while resistant to ampicillin and penicillin G. In addition, the strain was neither auto-agglutinating nor hemagglutinating, but it was hemolytic against erythrocytes from sheep, rabbit, tilapia, and grouper. The bacteria could be reisolated from kidney, liver, and the transparent yellow fluid of swollen intestine of moribund groupers after bacterial challenge and re-identified as the same species. The LD50 value was 2.53 x 10(7) colony forming units/g grouper body weight.

Classification of Vibrio vulnificus strains by the carbohydrate composition of their capsular polysaccharides

Pathogenic bacteria are often classified on the basis of the complex polysaccharides found on the surface, usually capsular polysaccharides or lipopolysaccharides. It is common in clinical practice to use reactivity with antisera specific to the various cell surface carbohydrates for this purpose. In this work, we describe a chemotyping method for bacterial capsular polysaccharides which is based on a carbohydrate analysis of an acid hydrolysate of the capsule. High-performance anion-exchange chromatography at high pH (HPAE) with electrochemical detection, which is used for analysis of the hydrolysate, shows preferential sensitivity for sugars. A single acid hydrolysis condition is chosen for screening a large collection of bacterial isolates and a computerized autosampler is used to make possible a large number of rapid analyses. This procedure does not yield a quantitative carbohydrate analysis for the sample but produces a fingerprint which can be used to discriminate among isolates which have different capsular polysaccharide structures. The procedure has been applied to a collection of 120 isolates of Vibrio vulnificus, a water-born species common in shellfish which causes septicemia in immunocompromised individuals, most often from eating of raw oysters. The collection of bacterial isolates includes strains from both clinical cases of septicemia and from such environmental sources such as sea water, sediments, and shellfish. Our results show that a number of unusual sugars including many amino sugars are found in these polysaccharides and that a wide variety of capsular carbotypes in V. vulnificus may be readily distinguished by the HPAE fingerprint.

Vibrio vulnificus infection reporting on death certificates: the invisible impact of an often fatal infection

This study assessed accuracy of (a) recording Vibrio vulnificus infection on death certificates and (b) International Classification of Disease (ICD)-9 codes for V. vulnificus. Patients with microbiologically confirmed V. vulnificus infection were identified as part of co-ordinated surveillance in four USA Gulf Coast states between 1989 and 1993. Of 60 deaths, 51 death certificates were reviewed and V. vulnificus was recorded as the immediate cause of death on 11 (22%). There was no ICD-9 code for V. vulnificus infection, thus no patients had an ICD-9 code indicating V. vulnificus infection. Of 23 certificates where V. vulnificus was recorded on the death certificate, only 5 (22%) were coded for Gram-negative, septicaemia. This study highlights the importance of teaching physicians how to provide epidemiologically meaningful data on death certificates and the need for accurate ICD mortality codes.

Molecular typing of Vibrio vulnificus isolates by random amplified polymorphic DNA (RAPD) analysis

This study was undertaken to determine molecular types and genetic similarity among V. vulnificus isolates by RAPD analysis. We compared these results with serotypes of V. vulnificus. Ninety-seven V. vulnificus strains including 69 strains from Chonnam University Hospital (CUH; Kwangju, Korea), 13 from Wonkwang University Hospital (WUH; Iksan, Korea), 13 from the Japanese National Institute of Health (JNIH) and two reference strains (ATCC 33815 and ATCC 27562) were analyzed. Four molecular types comprising all the strains were obtained by RAPD analysis. Type I was the most common (60/95) and included 58 strains from CUH. Type I showed a further subdivision into seven subtypes. Type II (23/95) composed of 11 strains from CUH, nine from WUH, three from JNIH and two reference strains. Six type III strains comprised four WUH strains and two JNIH strains. All six strains of type IV were from JNIH. The range of genetic similarity values among V. vulnificus isolates was 0.24 to 1.00. The serotypes of 95 strains were 04 (84.2%), 014 (3.2%), 01 (2.1%), 013 (2.1%), and R (2.1%). The most common 04 serotype strains were distributed among types I (60 strains), II (23 strains), III and IV (six strains). Although the V. vulnificus isolates showed a wide range of genetic similarity values, RAPD analysis could separate V. vulnificus strains into four molecular types, and the isolates from the same hospitals tended to belong to the same molecular type. There was no specific correlation between molecular types and serotypes of V. vulnificus.

Detection of Vibrio cholerae and V. mimicus heat-stable toxin gene sequence by PCR

Previously the heat-stable enterotoxin in Vibrio cholerae and V. mimicus has been detected by suckling mouse assay, a non-specific approach, and by DNA probes, a time-consuming method. This report describes a polymerase chain reaction (PCR) procedure for the detection of the stn (NAG-ST) and sto (O1-ST) gene sequences that is rapid and specific, allowing toxin gene molecular characterisation. A total of 34 V. cholerae and V. mimicus isolates was examined for ST and CT genes. The NAG-ST gene sequence was amplified in 13 of 22 non-O1/non-O139 V. cholerae and three of five V. mimicus strains. A new enterotoxin gene sequence pattern was found with MseI and TaqI restriction endonuclease PCR fragment digestion of two V. cholerae isolates, in addition to the pattern anticipated from the Genbank sequence, and found with the other ST+. These results show that ST-PCR detection is useful for the characterisation of V. cholerae and V. mimicus.

Comparison of ribotyping and randomly amplified polymorphic DNA PCR for characterization of Vibrio vulnificus

A total of 85 isolates of Vibrio vulnificus were characterized by ribotyping with a probe complementary to 16S and 23S rRNA of Escherichia coli and by randomly amplified polymorphic DNA-PCR (RAPD-PCR) with a 10-mer oligonucleotide primer. The RAPD-PCR results were scanned, and the images were analyzed with a computer program. Ribotype membranes were evaluated visually. Both the ribotyping and the RAPD-PCR results showed that the collection of strains was genetically very heterogeneous. Ribotyping enabled us to differentiate U.S. and Danish strains and V. vulnificus biotypes 1 and 2, while the RAPD-PCR technique was not able to correlate isolates with sources or to differentiate the two biotypes, suggesting that ribotyping is useful for typing V. vulnificus strains whereas RAPD-PCR profiles may subdivide ribotypes. Two Danish clinical biotype 2 strains isolated from fishermen who contracted the infection cleaning eels belonged to the same ribotype as three eel strains (biotype 2), providing further evidence that V. vulnificus biotype 2 is an opportunistic pathogen for humans. One isolate (biotype 2) from Danish coastal waters also showed the same ribotype as the eel strains. This is, to our knowledge, the first time the isolation of V. vulnificus biotype 2 from coastal waters has been described.

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.

Intraspecific characterization of Vibrio tapetis strains by use of pulsed-field gel electrophoresis, ribotyping, and plasmid profiling

A total of twenty-two strains of Vibrio tapetis, the causative agent of brown ring disease affecting cultured clams, were compared and evaluated in an investigation of strain heterogeneity using pulsed-field gel electrophoresis (PFGE), ribotyping, and plasmid profile analysis. A total of 90.9% of V. tapetis strains tested by using NotI showed the same PFGE pattern, consisting of 15 bands. In contrast, the V. tapetis strains showed a low degree of similarity with six reference Vibrio species tested. All V. tapetis strains harbored a large plasmid of 74.5 kb. This plasmid was not detected in any of the other Vibrio species. In addition, endonuclease restriction analysis of the plasmid content of the strains using EcoRI and HindIII clearly showed that all the strains of V. tapetis possessed the same cleavage pattern. The three enzymes used for ribotyping, PvuII, SmaI, and SalI, yielded patterns with 8 to 12 bands ranging in size from 2 to 23 kb. The application of the SalI and SmaI endonuclease rendered the separation of the strains tested in two ribotypes, while all the V. tapetis strains belonged to the same ribotype when the enzyme PvuII was used.

Pathogenic vibrios in the natural aquatic environment

In recent years, members belonging to the genus Vibrio of the family Vibrionaceae have acquired increasing importance because of the association of several of its members with human disease. The most feared of the Vibrio species is Vibrio cholerae, the causative agent of cholera, a devastating disease of global significance. Other important vibrios of medical importance are V. parahemolyticus, V. vulnificus, V. mimicus, and to a lesser extent V. fluvialis, V. furnissii, V. hollisae, and V. damsela. Recent studies have also implicated V. alginolyticus and V. metschnikovii in human disease, although their complete significance has not yet been established. The virulence of all medically important vibrios is aided by a variety of traits that help breach human defenses. In this review, we provide an overview of the environmental distribution of the pathogenic vibrios and the important virulence traits that enable them to cause disease.

[Primary Vibrio vulnificus septicemia. 1st documented case in the French West Indies]

BACKGROUND

Vibrio vulnificus is a non-choleric halophilic vibrion widely distributed in marine environments. Contamination in humans is uncommon except in coastal areas of the United States and Asia. We report the first documented case in the French West Indies.

CASE REPORT

A 57-year-old native with alcoholic cirrhosis was hospitalized for septic shock. The infectious syndrome began suddenly a few hours earlier with fever, diarrhea, and intense pain in the calf muscles. In the absence of a suspected agent, a wide spectrum antibiotic was prescribed. On day 3, bullae developed over the legs and progressed, despite early surgical debridement, to bilateral rapidly extensive necrosing cellulitis. An above the knee amputation was required but did not prevent death on day 9 due to irreversible multiple organ failure. Blood cultures were positive for V. vulnificus.

DISCUSSION

Primary septicemia due to V. vulnificus is mainly observed in subjects with an underlying liver disease and usually occurs after ingestion of contamined raw halieutic products such as oysters. The clinical presentation is characteristic with secondary necrotic ulcerations on the lower limbs. Improvement in the extremely poor prognosis of these infections depends on early initiation of an effective antibiotic with wide exeresis of necrotic tissue. Physicians should be aware of this severe infection despite its low frequency.

[Phagovars of halophilic vibrios]

The results of the phage typing of 164 halophilic vibrios revealed the most frequent combinations of lysing monophages, denoted by numbers: 1 (A, B, C, D), 2 (B, C, D), 3 (B, C) and 4 (C). In accordance with the proposed scheme, the phage typing of 398 cultures from different ecosystems was carried out. Phagovar was determined in 77.1% of the cultures. Most frequently occurred phagovars 1 (31.9%), 4 (15.8%), 3 (6%), and 2 (3.7%). Their proportion was 61%. 11 other phage combination causing the lysis of the cultures constituted 16.1%; 22.9% of the cultures could not be types. The use of the proposed scheme of phage typing permitted the determination of the temporal, regional, ecosystemic features of the circulation of halophilic vibrios in different ecosystems and regions, which was important for epidemiological analysis.

Pathogenicity of Vibrio anguillarum serogroup O1 strains compared to plasmids, outer membrane protein profiles and siderophore production

The virulence of 18 strains of Vibrio anguillarum serogroup O1 was compared to plasmid content, expression of siderophores and outer membrane proteins. All strains, irrespective of plasmid content, produced siderophores and inducible outer membrane proteins under iron-limited conditions. Only strains that carried the 67 kbp virulence plasmid or derivatives of it produced the outer membrane protein, OM2. All virulent strains harboured the 67 kbp plasmid or derivatives of it, indicating its importance for virulence. However, some strains carrying the virulence plasmid or a derivative of it, produced siderophores as well as OM2 but were non-pathogenic to fish. Likewise, among the virulent strains, considerable variation in LD50 values was recorded. Plasmid profiling and restriction analysis showed that the virulence plasmid existed in various molecular weights from 26 to 80 kbp, with 65-67 kbp being the most common, and that this plasmid displayed various restriction profiles. The presence of other plasmids did not seem to affect the pathogenic properties.

Vibrio anguillarum serogroup O3 and V. anguillarum-like serogroup O3 cross-reactive species--comparison and characterization

Forty-five Vibrio anguillarum-like isolates reacting with V. anguillarum serogroup O3 antiserum were examined in 30 characters to clarify their phenotypical properties, while their genotype was examined by ribotyping. The strains were isolated from diseased and dead fish or from environmental sources such as water, sediment, plankton, and faeces and gills of healthy fish. Phenotypically, the similarity of all the strains was more than 90%. However, significant differences between the fish-associated and environmental strains were detected. Biochemically, deviations were found in the Voges-Proskauer test and lysine decarboxylase reaction. Clustering analysis of the ribotypes showed two distinct clusters with a similarity of only 32%. Two strains representing each of these groups were used in a LD50 study, which showed some difference also in the pathogenicity between environmental and fish strains. It is suggested that the environmental strains belong to another species than V. anguillarum, but serologically cross-reacting with the V. anguillarum serogroup O3. The ribotyping as well as biochemical results indicated that the environmental strains possibly belong to Vibrio aestuarianus. The bona fide V. anguillarum serogroup O3 strains proved to be very homogeneous both phenotypically and genotypically, and the similarity of ribotypes was more than 96%. The V. anguillarum-like, serogroup O3-reactive strains from the environment were more heterogeneous in their biochemical behaviour, and showed an approximately 70% similarity in ribotypes.

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.

Viability during storage and stability of plasmids during storage and subculturing in strains of Vibrio anguillarum

The stability of plasmids, 3.3 kb - approximately 200 kb, in 8 strains of Vibrio anguillarum displaying different plasmid profiles and reactions with O-antisera was investigated over an 18 months period. All plasmid profiles proved to be resistant to storage at different temperatures but strains stored at 37 degrees C were only viable for a short period of maximum 2 months. Strains stored at 5 degrees C and 20 degrees C were viable for a longer period. Viable strains maintained their plasmid profile throughout the experiment, except in 2 cases where a 67 kb and a 200 kb plasmid were lost. Strains stored at -80 degrees C all remained viable and maintained their plasmid profile throughout the study. By subcultivating daily for up to 100 successive days, most strains maintained their plasmid profiles. Only 2 strains lost their plasmid. When picking 100 single colonies from agar plates, none of the colonies showed plasmid profiles deviating from the expected. The results suggest that plasmid profiles among V. anguillarium are very stable during subculturing, storage and laboratory handling using standard laboratory procedures, and thus, reliable for epidemiological investigations. In a second experiment, 2 pairs of 2 strains were grown together in mixed cultures. They were identical in all traits, except that one strain in each pair harboured the 67 kb pJM1-like virulence plasmid, whereas the other had lost this plasmid. The result showed that the growth rate was the same for strains with and without the plasmid, indicating that under laboratory conditions, this plasmid is neither a benefit nor the opposite for bacterial growth.

Vibrio scophthalmi sp. nov., a new species from turbot (Scophthalmus maximus)

Six strains isolated from the intestines of juvenile turbot in a fish hatchery in the north of Spain were found to be phenotypically members of the genus Vibrio. However, the phenotypic traits of these organisms did not place them in any of the currently known Vibrio species. These isolates formed an homogeneous group in which the DNA-DNA similarity values (the differences between the thermal denaturation midpoints of the homologous and heterologous duplexes) with reference strain A089T (T = type strain) ranged from 0 to 1.7 degrees C. The results of a 16S rRNA sequence analysis of A089T placed this strain in the genus Vibrio in the gamma subclass of the Proteobacteria. The closest relative is Vibrio aestuarianus, with a sequence similarity of 97.8%. This group of strains can be easily differentiated from the other Vibrio species by their clear phenotype. We propose the name Vibrio scophthalmi sp. nov. for these strains; the type strain is strain A089 (= CECT 4638).