Studies on the enteropathogenic, facultatively halophilic bacterium, Vibrio parahaemolyticus. II. Serological characteristics

Immunomagnetic separation and coagglutination of Vibrio parahaemolyticus with anti-flagellar protein monoclonal antibody

Mice were immunized by injection of Vibrio parahaemolyticus ATCC 17802 polar flagellin in order to produce monoclonal antibodies (mAbs). mAbs were analyzed by anti-H enzyme-linked immunosorbent assay using V. parahaemolyticus polar flagellar cores. The mAb exhibiting the highest anti-H titer was coated onto Cowan I Staphylococcus aureus cells at a concentration of 75 microg/ml cell suspension and used for slide coagglutination. Of 41 isolates identified genetically as V. parahaemolyticus, 100% coagglutinated with the anti-H mAb within 30 s, and the mAb did not react with 30 isolates identified as Vibrio vulnificus. A strong coagglutination reaction with V. parahaemolyticus ATCC 17802 was still observed when the S. aureus cells were armed with as little as 15 microg of mAb/ml S. aureus cell suspension. At this concentration, the mAb cross-reacted with three other Vibrio species, suggesting that they share an identical H antigen or antigens. The anti-H mAb was then used to optimize an immunomagnetic separation protocol which exhibited from 35% to about 45% binding of 10(2) to 10(3) V. parahaemolyticus cells in phosphate-buffered saline. The mAb would be useful for the rapid and selective isolation, concentration, and detection of V. parahaemolyticus cells from environmental sources.

Pathogenic Factors of Vibrios with Special Emphasis on Vibrio vulnificus

Bacteria of the genus Vibrio are normal habitants of the aquatic environment and play roles for biocontrole of aquatic ecosystem, but some species are believed to be human pathogens. These species can be classified into two groups according to the types of diseases they cause: the gastrointestinal infections and the extraintestinal infections. The pathogenic species produce various pathogenic factors including enterotoxin, hemolysin, cytotoxin, protease, siderophore, adhesive factor, and hemagglutinin. We studied various pathogenic factors of vibrios with special emphasis on protease and hemolysin of V. vulnificus. V. vulnificus is now recognized as being among the most rapidly fatal of human pathogens, although the infection is appeared in patients having underlying disease(s) such as liver dysfunction, alcoholic cirrhosis or haemochromatosis. V. vulnificus protease (VVP) is thought to be a major toxic factor causing skin damage in the patients having septicemia. VVP is a metalloprotease and degrades a number of biologically important proteins including elastin, fibrinogen, and plasma proteinase inhibitors of complement components. VVP causes skin damages through activation of the Factor XII-plasma kallikrein-kinin cascade and/or exocytotic histamine release from mast cells, and a haemorrhagic lesion through digestion of the vascular basement membrane. Thus, the protease is the most probable candidate for tissue damage and bacterial invasion during an infection. Pathogenic roles and functional mechanism of other factors including hemolysins of V. vulnificus and V. mimicus are also shown in this review article.

Arsenate resistance as a possible marker in the differentiation of environmental and clinical isolates of Vibrio parahaemolyticus

Strains of Vibrio parahaemolyticus were isolated from clinical, marine and freshwater fish of Calcutta, West Bengal, India. Drug and metal resistance characteristics were compared for differentiation of clinical and environmental strains. Eighteen out of the twenty environmental isolates were resistant to arsenate, unlike the clinical isolates which were all susceptible. All the thirty-five isolates of V. parahaemolyticus were resistant to ampicillin and streptomycin.

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.

Production of thermostable direct hemolysin by Vibrio parahaemolyticus enhanced by conjugated bile acids

The effects of conjugated bile acids, glycocholic acid, and taurocholic acid (TC) on production of thermostable direct hemolysin (TDH) by Vibrio parahaemolyticus were determined by a reversed passive latex agglutination assay against TDH. The amount of TDH excreted in growth medium containing either glycocholic acid or taurocholic acid (5 mM/liter) was, on a per-cell basis, 4- to 16-fold greater than that excreted in medium without the bile acids. The amounts of TDH released from lysed cells grown with the bile acids (5 mM/liter) were 4- to 32-fold greater than those from lysed cells grown without, suggesting that the bile acids enhanced synthesis of TDH within bacterial cells. These data imply that the conjugated bile acids play a key role in the pathogenicity of V. parahaemolyticus.

Coagglutination of Vibrio cholerae, Vibrio mimicus, and Vibrio vulnificus with anti-flagellar monoclonal antibody

Monoclonal antibodies (MAbs) with serological activity for purified flagellar (H) core protein prepared from Vibrio cholerae were identified by enzyme-linked immunosorbent assay. Four of these MAbs reacted with the flagella of V. cholerae and V. mimicus exclusively, while eight MAbs reacted with at least 1 of 30 heterologous Vibrio species tested by enzyme-linked immunosorbent assay or coagglutination. It appears that V. cholerae and V. mimicus express similar, if not identical, H determinants unique to these two Vibrio species. Staphylococcus aureus cells or latex beads armed with the four species-specific MAbs coagglutinated each of 47 isolates identified bacteriologically as V. cholerae or V. mimicus from among 103 Vibrio isolates tested. One coagglutination reagent armed with anti-V. vulnificus H MAb exhibited species specificity in that only V. vulnificus cells were coagglutinated from among the 31 Vibrio species examined. This reagent coagglutinated 20 isolates identified bacteriologically as V. vulnificus in a serological survey. MAb coagglutination reagents offer a rapid, specific, and economical alternative to the classical bacteriological approach to identify the human pathogens V. cholerae, V. mimicus, and V. vulnificus.

Current perspectives on the epidemiology and pathogenesis of clinically significant Vibrio spp

Recent taxonomic advances have now implicated several different Vibrio species as human pathogens. While the most common clinical presentation of Vibrio infection continues to be gastroenteritis, an increasing number of extraintestinal infections are being reported, particularly in immunocompromised individuals. Detection of Vibrio infections requires a good clinical history and the use of appropriate isolation and identification procedures by the laboratory to confirm illnesses attributed to Vibrio species. Except for Vibrio cholerae O1 and Vibrio parahaemolyticus, there is little direct evidence linking the production of a myriad of cell-associated or extracellular factors produced by each species with human disease and pathogenesis. Many questions regarding pathogenic Vibrio species remain unanswered, including their frequency and distribution in environmental specimens (water, shellfish), infective doses, virulence potential of individual isolates, and markers associated with such strains.

Rapid serological identification of Vibrio vulnificus by anti-H coagglutination

Staphylococcus aureus Cowan 1 cells were armed with anti-flagellar (anti-H) antibody produced in rabbits immunized with flagellar core protein prepared from Vibrio vulnificus. This reagent was assessed by coagglutination for its capacity to agglutinate and identify V. vulnificus. A species-specific H antigen is expressed in the core proteins of the polar flagella of V. vulnificus. Of 435 V. vulnificus isolates identified bacteriologically, 432 (99.3%) were agglutinated in the slide test within 2 min after the addition of the anti-V. vulnificus H coagglutination reagent. Other than Vibrio pelagius, the reagent did not agglutinate 19 heterologous Vibrio spp. tested, including 290 V. cholerae, 22 V. mimicus, 395 V. parahaemolyticus, and 16 V. fluvialis isolates recovered from seafood and the marine environment. The serological resolution of the coagglutination reaction was enhanced if the organism under test was suspended in 0.1 M Tris buffer-0.1 mM EDTA-1.0% Triton X-100 (TET) for 24 h before serological examination. The TET buffer also increased the sensitivity of the coagglutination reaction 100-fold over that for isolates suspended in 0.3% formalinized phosphate-buffered saline before testing. The anti-H coagglutination test is a rapid, serologically specific, and inexpensive procedure for identifying V. vulnificus one step beyond primary isolation.

Presumptive identification of Vibrio species with H antiserum

Species in the genus Vibrio exhibit flagellar (H) antigens unique to the species. Thus, species-specific H antiserum could be a valuable reagent with which to screen serologically large numbers of Vibrio isolates. Antisera against V. cholerae, V. fluvialis, V. anguillarum, V. metschnikovii, V. parahaemolyticus, V. alginolyticus, and V. vulnificus H antigens was produced in rabbits by repeated injections of Formalin-preserved whole cells. Anti-O activity and anti-H activity against common H antigens was absorbed from each antiserum, V. fluvialis was shown to possess an H antigen unique to the species and also to share minor H antigens with V. cholerae, V. metschnikovii, and V. anguillarum. V. vulnificus also exhibits a species-unique H antigen. A comprehensive serological screening system based on species-specific H antiserum was developed to identify pathogenic Vibrio species one step beyond primary isolation. Vibrio species were correctly identified with accuracies ranging from 93 to 100%. Some isolates were either nonmotile or poorly so and thus did not flocculate in H antiserum.

Vibrio parahaemolyticus and related halophilic Vibrios

Approximately 30 years have elapsed since Dr. Fujino's original discovery that Vibrio parahaemolyticus (then termed Pasteurella parahemolytica) was the cause of "summer diarrhea" in Japan. Since that finding, V. parahaemolyticus has been established as a cause of gastroenteritis in numbers and places approaching global proportions. It has been isolated in marine and estuarine areas almost worldwide and despite its halophilic nature, V. parahaemolyticus has been isolated from saline-free waters. The relationship of this organism to the environment reveals a close association with other marine organisms especially copepods on which the Vibrios depend for survival in winter months and growth in summer months. There is a uniquely provocative disparity between human strains of V. parahaemolyticus which are Kanagawa phenomenon (KP) positive and the environmental strains which to a large extent are KP negative, the significance being that pathogenicity is measured according to the Kanagawa phenomenon (hemolytic activity) reaction. The hemolysin of the pathogenic strains is a thermostable, cardiotoxic protein, which thus far has not been implicated in the mechanism(s) which causes human gastroenteritis. The interest in this organism has been widened in recent years by the finding that similar organisms, V. alginolyticus, lactose positive vibrios and group F vibrios also cause serious disease in humans.

Kanagawa phenomenon and serotypic pattern of Vibrio parahaemolyticus strains isolated from various sources in Calcutta

A total of 135 strains of Vibrio parahaemolyticus isolated during the period 1976-77 from human gastroenteritis cases and various categories of environmental sources, e.g., crustaceans, fish and different water samples (pond, stored, open well and tap water) were tested for their Kanagawa phenomenon and serotypic pattern. Amongst the 80 human isolates tested, 69 strains (86.3%) were Kanagawa phenomenon positive, and 60 strains (75.0%) were serologically typable--the dominant serotype being 05:K15. Of the 25 isolates from various water sources 10(40.0%) were Kanagawa phenomenon positive, and 17(68.0%) were serologically typable and 4 (23.5%) of them belonged to serotype 05:K15. All the 30 strains isolated from crustaceans and fish were Kanagawa phenomenon negative and 22 (73.3%) of them were serologically typable, belonging to heterogeneous serotypes. The results of this study also indicate the possible role of water in the transmission of V. parahaemolyticus infection in Calcutta slums.

The distribution of Vibrio parahaemolyticus in British coastal waters: report of a collaborative study 1975--6

A collaborative survey has shown that V. parahaemolyticus is widely distributed in British coastal waters, sediments and shellfish, especially in southern and western areas. The relatively small numbers in the environment do not present significant health hazards from marine products, provided that processing, storage and distribution are adequate. The presence of this organism in small numbers in British coastal waters or in shellfish should not in itself be regarded as cause for concern.

Tolerance and other biological properties of Vibrio parahaemolyticus endotoxins

Biological properties of endotoxins prepared from three strains of Vibrio parahaemolyticus were compared with reference to commercially prepared Salmonella typhi endotoxin. Endotoxin assays performed in rabbits included dermal Shwartzman reactivity, pyrogenicity, heat stability, and ability to induce tolerance as well as cross-tolerance. Mice were used for endotoxin LD50 determinations. Results showed V. parahaemolyticus endotoxins were similar to that of S. typhi strain O901. Induction of tolerance to V. parahaemolyticus strain 11590 endotoxin resulted in complete cross-tolerance to S. typhi endotoxin, and vice versa. Partial cross-tolerance to S. typhi endotoxin was demonstrated with rabbits rendered tolerant to endotoxin from V. parahaemolyticus strains Sak-3 and FC1011. Absorption spectra, nitrogen, phosphorus and carbohydrate analyses revealed additional similarities between endotoxins from V. parahaemolyticus and endotoxin from a member of the Enterbacteriaceae.

Vibrio cholerae flagellar antigens: a serodiagnostic test, functional implications of H-reactivity and taxonomic importance of cross-reactions within the Vibrio genus

Serodiagnostic tests for all serotypes of Vibrio cholerae using H-antisera were investigated. Activity motile cell lines of 155 stock and international reference cultures of human, animal, fish, and halophilic Vibrios, Aeromonas, Comomonas, Pseudomonas, Salmonella, and Escherichia were investigated. Without exception, all cholera vibrios (including the NAG serotypes) reacted with H sera. Positive reactions were obtained specifically (a) within 2 hrs at 52 degrees C in the tube test using thick formalized suspensions and H antisera at optimal proportion titre and (b) within 30 sec by slide agglutination of fresh cultures. The other vibrios investigated reacted similarly with their homologous H antisera. 2. The rapid diagnostic techniques of fluorescent antibody labeling or immobilization were unsuccessful, V. cholerae flagella being refractive to H sera in these tests. V. cholerae was, however, sensitive in a type-specific manner to O antisera. These and related observations suggest that O antigen has a functional role in Vibrio motility. 3. Interspecies H cross-reactions between V. cholerae and fish and animal vibrios which correlated with bacteriologic similarity, were demonstrated. O antigens of these vibrios were strain specific. Cross-absorption analysis indicated that the H antigens of vibrios were characteristic and homogenous within the species, and therefore a potentially important taxonomic criterion of Vibrio species.

Antigenic relationships among strains of Vibrio parahaemolyticus

The antigenic relationships of 79 strains of Vibrio parahaemolyticus representing 46 assigned K-types were studied by tube agglutination. Homologous titers of 46 anti-K sera ranged from 80 to 2,560. All but three sera exhibited from one to six heterologous reactions, the majority of which gave titers of </=20, but 19 sera showed cross-reactions whose titers exceeded 40. Nine reciprocal and 16 unilateral relationships were described. Some of the cross-reactions involved heat-extractable K-antigens, as determined by absorption with nonheated and heated heterologous antigens, whereas others did not involve K-antigens since absorption with the heterologous antigens had no effect on the homologous systems. On the basis of the reactions of selected antisera to the O-antigens of some of the K-strains, the cross-reactions could not be explained solely on the basis of O-specificities.

Procedure for isolation and enumeration of Vibrio parahaemolyticus

An evaluation of criteria used in the identification of Vibrio parahaemolyticus showed that cultural responses varied with respect to growth in broth with 10% NaCl, type of hemolysis, reactions in triple sugar-iron-agar, and serological reactions. With few or no exceptions, cultures were positive for cytochrome oxidase, utilized glucose fermentatively, were sensitive to pteridine (0/129) and novobiocin, and failed to grow in Trypticase soy broth (TSB) without NaCl. A procedure employing a direct plating technique, with or without prior enrichment, was designed for the isolation and enumeration of V. parahaemolyticus. The plating medium consisted of 2.0% peptone, 0.2% yeast extract, 1.0% corn starch, 7% NaCl, and 1.5% agar, with the pH adjusted to 8.0. The enrichment broth was TSB with 7% NaCl. Dilutions of food homogenates were either spread directly on the plates or inoculated into enrichment broth. TSB enrichments were incubated at 42 C for 18 hr. A loopful of the TSB tubes then was streaked onto the direct plating medium. Incubation of plates was at 42 C for 24 to 48 hr. Smooth, white to creamy, circular, amylase-positive colonies were then picked as suspect V. parahaemolyticus. Confirmation of gram-negative, fermentative, oxidase-positive, pleomorphic rods sensitive to pteridine 0/129 was made by a fluorescent-antibody technique. With this procedure, a satisfactory quantitative recovery of known V. parahaemolyticus from inoculated seafoods was made possible. V. parahaemolyticus was nto isolated from other salted foods.

Polyphasic taxonomy of the genus vibrio: numerical taxonomy of Vibrio cholerae, Vibrio parahaemolyticus, and related Vibrio species

A set of 86 bacterial cultures, including 30 strains of Vibrio cholerae, 35 strains of V. parahaemolyticus, and 21 representative strains of Pseudomonas, Spirillum, Achromobacter, Arthrobacter, and marine Vibrio species were tested for a total of 200 characteristics. Morphological, physiological, and biochemical characteristics were included in the analysis. Overall deoxyribonucleic acid (DNA) base compositions and ultrastructure, under the electron microscope, were also examined. The taxonomic data were analyzed by computer by using numerical taxonomy programs designed to sort and cluster strains related phenetically. The V. cholerae strains formed an homogeneous cluster, sharing overall S values of >/=75%. Two strains, V. cholerae NCTC 30 and NCTC 8042, did not fall into the V. cholerae species group when tested by the hypothetical median organism calculation. No separation of "classic" V. cholerae, El Tor vibrios, and nonagglutinable vibrios was observed. These all fell into a single, relatively homogeneous, V. cholerae species cluster. V. parahaemolyticus strains, excepting 5144, 5146, and 5162, designated members of the species V. alginolyticus, clustered at S >/=80%. Characteristics uniformly present in all the Vibrio species examined are given, as are also characteristics and frequency of occurrence for V. cholerae and V. parahaemolyticus. The clusters formed in the numerical taxonomy analyses revealed similar overall DNA base compositions, with the range for the Vibrio species of 40 to 48% guanine plus cytosine. Generic level of relationship of V. cholerae and V. parahaemolyticus is considered dubious. Intra- and intergroup relationships obtained from the numerical taxonomy studies showed highly significant correlation with DNA/DNA reassociation data.

Isolation of Vibrio parahaemolyticus from the processed meat of Chesapeake Bay blue crabs

A method for the recovery of Vibrio parahaemolyticus from seafoods is described. By this procedure, a total of 56 biochemically positive cultures of V. parahaemolyticus were recovered from market samples of Chesapeake Bay processed blue crab (cooked, picked, packed, and refrigerated meat). All of the isolates were tested serologically, and 22 strains were serotyped according to the schema of Sakazaki as follows: K3, K5, K28, K31, K36, K37, K39, K43, and K44. These results indicate the broad distribution of these specific serotypes in a seafood harvested from the Chesapeake Bay.

Comparative Hemolytic Activity of Vibrio parahaemolyticus and Related Vibrios

The hemolytic activities of 91 strains of Vibrio parahaemolyticus isolated from human diarrheal stools, sea fish, and sea water; 21 suspected V. parahaemolyticus cultures isolated from wound infections; 14 nonpathogenic marine vibrios; and 21 V. parahaemolyticus isolated from moribund blue crabs Callinectes sapidus were compared. Potentially pathogenic V. parahaemolyticus strains could be differentiated from the related nonpathogenic marine vibrios, because the former hemolyzed hamster, sheep, and human blood, whereas the latter were nonhemolytic. In addition, V. parahaemolyticus isolated from tissue infections could be differentiated from those of the first group isolated from sea fish or human stools, because the former exhibited primarily an α-hemolytic reaction on chicken blood; the latter exhibited mostly β. It is suggested that V. parahaemolyticus isolated from blue crabs may be differentiated from the first group on the basis of their hemolysis of human blood. A useful schema of the differential hemolytic reactions, exhibited by V. parahaemolyticus , tissue infection vibrios, and nonpathogens on hamster, sheep, chicken, goose, and human blood is given. The patterns of hemolytic activity of these groups on special human blood-agar plates (Kanagawa hemolysis) resembled that seen on ordinary human blood-agar.