Vibrio parahaemolyticus outbreaks in the United States

Development of a rapid PCR protocol to detect Vibrio parahaemolyticus in clams

Vibrio parahaemolyticus is part of the natural microflora of estuarine and coastal marine waters and can be also present in seafood, especially shellfish and bivalve molluscs. In this study we compared the reference cultural method ISO 6887-3 with two molecular methods, multiplex PCR and real-time PCR, for the detection of two distinct genetic markers (tlh species-specific gene and tdh virulence gene) of V. parahaemolyticus in bivalve mollusc. The analyses were performed on clams inoculated with V. parahaemolyticus ATCC 43996 at T0 and after a 3 and 6 h of pre-enrichment in alkaline saline peptone water. Counts on agar plates were largely inaccurate, probably due to other Vibrio species grown on the TCBS selective agar. Multiplex PCR assays, performed using primers pairs for tdh and tlh genes, showed a detection limit of 10⁴ CFU/g of shell stock within 6 h of pre-enrichment, respecting however the action level indicated by the National Seafood Sanitation Program guideline. Detection by tdh gene in real-time PCR reached the definitely highest sensitivity in shorter times, 10¹ CFU/g after 3 h of pre-enrichment, while the sensitivity for the tlh gene was not promising, detecting between 10⁵ and 10⁶ CFU/g after 6 h of pre-enrichment. Our findings provide a rapid routine method of detection of V. parahaemolyticus based on tdh gene by real-time PCR for commercial seafood analysis to identify the risk of gastrointestinal diseases.

Note. Growth of Vibrio parahaemolyticus in lobster homogenates at different temperatures / Nota. Crecimiento de Vibrio parahaemolyticus en langosta a diferentes temperaturas

Due to the illnesses associated with the presence of Vibrio parahaemolyticus in seafoods, its survival in lobster was studied. Lobster homogenates were prepared, sterilized, inoculated with the bacteria, and incubated at -25 °C, 6 °C and 28 °C, for 60 days. Different viable cell counting methods were employed. The results of the McFarland nephelometric standard method and the direct count of viable bacterial cells, (DVC) were not significantly different (p = 0.5). However, the DVC method was better for detecting viable cells at low numbers for longer times, especially for cultures incubated at -25 °C. Therefore, this method, and the plate count (PC) method for counting colony forming units, were selected for monitoring the survival of V. parahaemolyticus under each temperature of incuba tion. The greatest survival of the bacterium was at ambient (28 °C) temperature. At freezer tempera ture (-25 °C), no viable cells were detected towards the end of the experiments. However, the cultures kept at 6 °C were viable until the end of the incubation period, these results being different from previously published works conducted at refrigeration temperatures.

Association of pandemic Vibrio parahaemolyticus O3:K6 present in the coastal environment of Northwest Mexico with cases of recurrent diarrhea between 2004 and 2010

In 2004, more than 1,230 cases of gastroenteritis due to pandemic O3:K6 strains of Vibrio parahaemolyticus were reported in southern Sinaloa, a state in Northwestern Mexico. Recurrent sporadic cases arose from 2004 to 2010, spreading from the south to the north. In the present study, Vibrio parahaemolyticus was detected in both environmental samples and clinical cases along the Pacific coast of Sinaloa during 2004 to 2010. An evaluation was made of the serotypes, distribution of virulence genes, and presence of pandemic O3:K6 strains. A total of 144 strains were isolated from environmental samples (from sediment, seawater, and shrimp), and 154 clinical strains were isolated. A total of 10 O serogroups and 30 serovars were identified in the strains. Environmental strains (n = 144) belonged to 10 O serogroups and 28 serovars, while clinical strains (n = 154) belonged to 8 O serogroups and 14 serovars. Ten serovars were shared by both environmental and clinical strains. Among 144 environmental isolates, 4.1% (6/144) belonged to the pandemic clone, with 83.3% containing the orf8 gene and with O3:K6 accounting for 67%. On the other hand, pathogenic strains (tdh and/or trh) accounted for 52% (75/144) of the environmental isolates. Interestingly, among 154 clinical isolates, 80.5% (124/154) were pandemic strains, with O3:K6 (tdh, toxRS(new), and orf8) representing the predominant serovar (99.2%, 123/124). Overall, our results indicate that in spite of a high serodiversity and prevalence of pathogenic Vibrio parahaemolyticus in the environment, the pandemic strain O3:K6 caused >79% of reported cases between 2004 and 2010 in Sinaloa, Mexico.

Vibrio parahaemolyticus associated with cholera-like diarrhea among patients in North Jakarta, Indonesia

A diarrhea study was conducted in North Jakarta, Indonesia from December 1996 through December 1997. Vibrio parahaemolyticus was isolated from 333 (6.1%) of 5442 rectal swab samples collected from patients with cholera-like diarrhea. Vibrio cholerae O1 was isolated from 545 (10.0%) and V. cholerae non-O1 from 183 samples (3.4%), respectively. Patients positive for V. parahaemolyticus were mostly adults between 20 and 40 years of age, with males constituting 62%. A majority (65%) of these patients demonstrated watery diarrhea with a frequency of fewer than 10 episodes per 24 hour. A large number of the patients had abdominal pain (83%) and vomiting (76%) and were non-febrile (90%). The highest isolation rate (9.6%) of V. parahaemolyticus was found during the dry season (June, July) and the lowest (4.5%) in the rainy season (December, January, February). All of the V. parahaemolyticus isolates were hemolytic on human blood agar (positive Kanagawa) but none was urease positive. Disk diffusion antibiotic susceptibility tests performed on the isolates demonstrated resistance to ampicillin (98%), cephalothin (24%), kanamycin (15%), colistin (97%), neomycin (2%) and ceftriaxone (0.3%). All isolates (100%) were sensitive to chloramphenicol, tetracycline, trimethoprim-sulfamethoxazole, gentamicin, and ciprofloxacin.

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.

Fatal Vibrio parahemolyticus septicemia in a patient with cirrhosis. A case report and review of the literature

Vibrio parahemolyticus has been well documented to cause outbreaks of infectious diarrhea, usually related to poor food handling; only rarely has it been reported to cause fetal septicemia. In contrast, Vibrio vulnificus is a well-known cause of septicemia, especially in patients with cirrhosis. A 31-year-old woman with cirrhosis who developed fatal V. parahemolyticus sepsis after ingesting raw seafood is described. We review the clinical syndromes associated with sepsis caused by these two organisms. Leg pain and bullous skin lesions may be a clue to the diagnosis. Febrile patients with cirrhosis should be questioned regarding recent seafood ingestion, and appropriate antibiotics chosen if this history is obtained. Physicians should inform patients at risk to avoid raw seafood in an attempt to prevent this potentially lethal syndrome.

Ocorrência de Vibrio parahaemolyticus em mexilhões (Perna perna, Linnaeus, 1758) de banco natural do litoral do município de Palhoça, Santa Catarina, Brasil

Foi estudada a ocorrência de Vibrio parahaemolyticus em quarenta amostras de mexilhões (Perna perna, Linnaeus, 1758) procedentes de banco natural da praia da Pinheira, município de Palhoça, Santa catarina, durante um período de três meses. Na metodologia de isolamento foi utilizada a técnica do Número Mais Provável (NMP) com enriquecimento em água alcalina peptonada e subseqüente plaqueamento em ágar TCBS (thiosulfate citrate bile salts sucrose). Em 52,5% das amostras de mexilhões foi constatada a presença de Vibrio parahaemolyticus, com níveis de contaminação entre <3 e 93 NMP/g. Na caracterização sorológica de 61 culturas, 36,1% não permitiram a identificação das estruturas antigênicas O e K; 54,1% somente da estrutura K e apenas 8,2% tiveram ambas as estruturas definidas. Nenhuma dessas culturas apresentou positividade para o teste de Kanagawa.

Víbrios não coléricos na rotina enterobacteriológica

De 3.250 fezes diarréicas, recebidas para diagnóstico microbiológico em laboratório clínico particular, no Recife, Brasil, isolaram-se 55 (1,7%) linhagens de Vibrio. O estudo foi realizado entre maio de 1989 e maio de 1991. Para o isolamento de Vibrio, os espécimes fecais foram enriquecidos em água peptonada alcalina suplementada com 2% de NaCl e subcultivados em ágar tiosulfato-citrato-sais biliares-sacarose (TCBS). Das espécies isoladas, V. parahaemolyticus foi a mais freqüente (24 cepas), seguida de V. furnissii (15 cepas), V. cholerae não 01 (6 cepas), V. alginolyticus (4 cepas), V. fluvialis (2 cepas) e Vibrio sp. (1 cepa). Do ponto de vista custo-benefício, a baixa taxa de isolamento de Vibrio levanta dúvidas acerca da utilidade do TCBS na rotina enterobacteriológica dos laboratórios clínicos

Therapy for acute infectious diarrhea in children

This article reviews current recommendations of therapy with antidiarrheal compounds and antimicrobial agents for acute infectious diarrhea in children. In most infants and children with acute infectious diarrhea, treatment with antidiarrheal compounds is not indicated. Many of these compounds interfere with identification of enteropathogens in stool specimens, and the antimotility class has an overdose potential. Antimicrobial therapy is given to reduce symptoms and to prevent the spread of infection by decreasing fecal shedding of organisms. Although effective therapy is not available for patients with enteric viruses, Cryptosporidium, and Microsporidium, therapy is useful for children with amebiasis, antimicrobial-associated colitis, cholera, giardiasis, various forms of Escherichia coli diarrhea and Salmonella disease, isosporiasis, shigellosis, and strongyloidiasis. For several other conditions, antimicrobial therapy is of questionable benefit (infection with Campylobacter jejuni or Yersinia enterocolitica, intestinal salmonellosis and enterohemorrhagic E. coli infection). Compounds such as the fluoroquinolones, which are effective in the treatment of acute infectious diarrhea in adults, are not approved for use in children because of potential side effects. Many bacterial, viral, and parasitic organisms cause acute infectious diarrhea; appropriate antimicrobial therapy requires the accurate, rapid identification of the offending enteropathogen. In children with an underlying illness such as acquired immunodeficiency syndrome, manifestations may be prolonged, severe, and recurrent despite appropriate therapy.

[Human gastroenteritis associated with Vibrio parahaemolyticus in Recife, Brazil]

A study was carried out on the occurrence of Vibrio parahaemolyticus in 1,100 diarrheal feces, routinely sent to a private clinical laboratory for microbiologic diagnosis, in Recife. V. parahaemolyticus was isolated from 14 (1.3%) fecal samples. However, if we considered only the specimens from adult patients, the isolation rate of V. parahaemolyticus rose to 7.1%. In most cases (92.86%), V. parahaemolyticus was the only enteropathogen recognized. Among the isolates, seven K antigen serovars were demonstrated, and three were untypable. Only two human isolates, both ureolytic, did not produce the thermostable direct hemolysin. We concluded that V. parahaemolyticus is an important cause of sea food linked diarrhea among adults in Recife.

Vibrio vulnificus infection in Hawaii

A life-threatening Vibrio vulnificus infection occurred in a 52-year-old Korean woman with hepatic cirrhosis. Four days after ingesting raw crab, the patient presented to the hospital with nausea, vomiting, fever, hypotension, and hemorrhagic blistering of the left foot. Vibrio vulnificus was recovered from both her blood and a foot wound.

Postoperative wound infection associated with Vibrio parahaemolyticus in a patient without exposure to seawater

This report describes a case of wound infection associated with Vibrio parahaemolyticus. The patient had ingested steamed crabs 7 days before admission for surgical treatment of intestinal obstruction due to colon carcinoma. The Vibrio sp. was isolated from postoperative wound drainage as well as from stool. Recovery was uneventful.

Occurrence of Vibrionaceae in natural and cultivated oyster populations in the Pacific Northwest

Studies were done to assess the role of oysters from the Pacific Northwest as a potential source of Vibrionaceae. Oysters collected from natural and cultivated populations on the British Columbia Coast were opened using sterile instruments. The gills and oyster meat were each removed, and the meat was cut in half. The gills and the cut surface of the oyster meat were each cultured by inoculating them directly to the surface of agar plating media for the isolation of Vibrionaceae. Overall, 120 oysters were cultured, and 60 yielded Vibrionaceae. Vibrio parahaemolyticus, Vibrio fluvialis, and Vibrio vulnificus were the most commonly isolated organisms. Vibrionaceae were most often recovered from oysters collected under warm-water conditions from natural stocks (83% positive), followed by oysters from the same sites collected under cold-water conditions (35% positive). Only 29% of oysters collected from cultivated commercial stocks under warm water conditions yielded Vibrionaceae, and no Vibrionaceae were isolated from oysters collected from these sites during periods when water temperatures were low. The results suggest that oysters are a significant source of potentially pathogenic Vibrionaceae in the Pacific Northwest. However, the risk of exposure to these bacteria can be reduced by consumption of cultivated oysters harvested under cold-water conditions.

Vibrio parahaemolyticus (Kanagawa-negative) wound infection in a hospital dietary employee

Vibrio parahaemolyticus is an estuarine bacterium that is a major cause of gastroenteritis worldwide. Occasionally, this organism has also been shown to be the causative agent of wound infections. In almost all cases of gastrointestinal disease only strains that produce hemolysin ("Kanagawa-positive") are implicated. We have isolated a Kanagawa-negative strain of V. parahaemolyticus from serous wound drainage of the infected foot of a hospital dietary employee. To our knowledge, this is only the third documented case of wound infection caused by such an organism. In this instance, the potential threat of nosocomial transmission was of special concern in that the wound infection was present in a hospital food handler.

Bacteriology of the marine environment: implications for clinical therapy

Ocean water and tissue samples were obtained from a variety of sources with phylogenetic and geographic diversity. Purified bacterial colonies were isolated and identification procedures were performed. A total of 67 isolates were recovered. Thirty-eight isolates belonged to the genus Vibrio and included six species. Twenty-four non-fermentative bacteria and four Gram-positive isolates were recovered. Antibiotic susceptibility testing showed that while the non-fermentative marine bacteria generally were susceptible to the antibiotics tested, marine Vibrio species were relatively resistant to a wide variety of antimicrobials. Antibiotics effective against all species included imipenem, trimethoprim/sulfamethoxazole, and chloramphenicol. Further recommendations for treatment are based on sensitivity in culture. Some isolates failed to grow in the medium used for susceptibility testing. Because commercial test kits may not yield accurate identifications of bacteria, the acquisition of antimicrobial susceptibility data gains added importance.

Widespread outbreaks of clam- and oyster-associated gastroenteritis. Role of Norwalk virus

Consumption of raw shellfish has long been known to be associated with individual cases and sporadic outbreaks of enteric illness. However, during 1982, outbreaks of gastroenteritis associated with eating raw shellfish reached epidemic proportions in New York State. Between May 1 and December 31, there were 103 well-documented outbreaks in which 1017 persons became ill: 813 cases were related to eating clams, and 204 to eating oysters. The most common symptoms were diarrhea, nausea, abdominal cramps, and vomiting. Incubation periods were generally 24 to 48 hours long, and the duration of illness was 24 to 48 hours. Bacteriologic analyses of stool and shellfish specimens did not reveal a causative agent. Norwalk virus was implicated as the predominant etiologic agent by clinical features of the illness and by seroconversion and the formation of IgM antibody to Norwalk virus in paired serum samples from persons in five (71 percent) of seven outbreaks in which testing was done. In addition, Norwalk virus was identified by radioimmunoassay in clam and oyster specimens from two of the outbreaks. Determining the source of the shellfish was not always possible, but northeastern coastal waters were implicated. The magnitude, persistence, and widespread nature of these outbreaks raise further questions about the safety of consuming raw shellfish.

Gastroenteritis in patients with stool isolates of Vibrio vulnificus

Vibrio vulnificus, a marine Vibrio associated with severe extraintestinal infections, has not been previously implicated as a cause of infectious diarrhea. Three patients were identified with diarrheal illness from whom this organism was the sole pathogen recovered from cultured stool specimens. All three had eaten raw oysters within one week of becoming ill. These patients were all taking medication that reduces gastric acidity, two were heavy drinkers of alcohol, and one had unrecognized colon cancer; these factors may have predisposed to the development of disease. Clinicians should consider that V. vulnificus may be a cause of gastroenteritis in patients who have consumed raw oysters.

Vibrio parahaemolyticus gastroenteritis. An outbreak associated with raw oysters in the Pacific northwest

During a 3-month period in the late summer and fall of 1981, six cases of gastroenteritis and one wound infection due to Vibrio parahaemolyticus were reported to public health agencies in Washington and Oregon. An investigation revealed that all of the gastroenteric illnesses were associated with eating raw oysters; that oysters eaten by five of the six patients were harvested at four divergent sites at Willapa Bay, Washington, a large commercial growing area; and that the V. parahaemolyticus isolates from those five patients were all Kanagawa positive, belonged to serotype 04:K12, and exhibited an atypical biochemical reaction, urea hydrolysis. No further cases linked to Willapa Bay oysters have been reported, and the infecting strain could not be found in sediment samples from the bay in February 1982. Thus, even though the origin of this self-limiting outbreak is obscure, the investigation demonstrated that the geographic distribution of V. parahaemolyticus infection in the United States includes the Pacific seacoast . Furthermore, oysters must be considered, along with crabs, shrimp, and lobster, as a vehicle of transmission of this infection in the United States.

Vibrio vulnificus infection. Case report and update since 1970

Vibrio vulnificus infections is being reported with increasing frequency in coastal regions of the United States. Raw seafood consumption, particularly raw oysters, and wounds acquired in a marine environment predispose to infection. Patients with advanced liver disease are at increased risk of developing septicemia. V. vulnificus is a virulent pathogen producing significant morbidity and mortality; its virulence relates in part to the production of exotoxin. Skin lesions occur early in the clinical course of infection and provide means of specific diagnosis. The patient and the consulting physician are well served by the dermatologist capable of recognizing this infectious disease.

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.

Vibrio metschnikovii bacteremia in a patient with cholecystitis

Vibrio metschnikovii was isolated from the blood of an 82-year-old patient with peritonitis and an inflamed gallbladder. This is probably the first clinically significant isolate of this new vibrio.

A Halophilic vibrio isolated from a case of chronic cholecystitis

We found a halophilic vibrio in B bile from a 75-year-old female patient with chronic cholecystitis, and examined its biochemical characteristics. The organisms are gram-negative short rods or comma shaped, with some ring forms. They have a single polar flagellum, but not capsule. The strains can grow in peptone water with 1.0 to 4.0% NaC1, but not with no NaC1 or 6.0% NaC1. The characteristics of the organisms are positive dextrose fermentation, catalase, oxidase, and ornithine decarboxylase, and negative lysine decarboxylase, arginine dihydrolase, and absence of gas from glucose. They are sensitive to 2,4-diamine-6,7-diisopropyl pteridine (0/129). These characteristics indicate that the isolated strain should be a halophilic vibrio. however, no growth on Salmonella-Shigella (SS), SS with added sucrose and bromcresol purple (SS-SB), MacConkey's or thiosulfate citrate bile salts (TCBS) agar plates was demonstrated. Nitrate reduction, Simmons' citrate agar, indole, omicron-nitrophenol-beta-d-galactopyranoside (ONPG), motility and esculin hydrolysis were positive. Urease, gelatinase, Voges-Proskauer, phenylalanine deaminase and malonate reactions were negative. Acid was produced from amygdalin, arabinose, cellobiose, fructose, galactose, glucose, lactose, maltose, mannitol, salicin, starch, sucrose, trehalose, and xylose, but not from adonitol, dulcitol, inositol, mannose, melibiose, raffinose, rhamnose and sorbitol. From these characteristics the isolate is considered to be not identical with V. parahaemolyticus, V. Cholerae, V. Vulnificus or other vibrios. It can be presumed that this isolate represents another species of halophilic vibrio.

Lactose-positive Vibrio in seawater: a cause of pneumonia and septicemia in a drowning victim

Lactose-positive Vibrio is a recently recognized marine organism that has pathogenic potential for humans. An organism was isolated from the sputum and blood of a man who was resuscitated after drowning in the sea. The isolates from both sources had the characteristics of lactose-positive Vibrio, which include positive oxidase, citrate, indole, and o-nitrophenyl-beta-D-galactopyranoside reactions and negative Voges-Proskauer, urease, and sucrose reactions. Seawater samples from 21 sites around Galveston Island were cultured for lactose-positive Vibrio over a period of 4 weeks, and 36% of the samples yielded the organism. The environmental isolates were very similar to the clinical isolates in biochemical reactions and susceptibility to antimicrobial agents. The results indicate that lactose-positive Vibrio is a common organism in the marine environment and that it should be considered in the diagnosis of infections, including pneumonia, associated with exposure to the sea.

Fulminating lactose-positive Vibrio septicemia

Recently cases of tissue invasion by as yet unnamed marine vibrios which were morphologically and biochemically similar to both Vibrio parahemolyticus and V. alginolyticus, but not identical with either of them, have been described. We have seen a patient who had serious widespread tissue infection with a halophilic, Gram-negative bacterium which was isolated from blood and leg lesions. The organism had the characteristics of the genus Vibrio, and lactose fermentation and ONPG reactions were positive. It also had a lower tolerance for sodium chloride in the nutrient broth compared with the above two vibrios. The isolate seems identical to the lactose positive (L+) Vibrio described by HOLLIS et al. (1976). Tissue infection resulting in severe necrotizing cellulitis and vasculitis was demonstrated at autopsy.

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.

Salt-starch xylose lysine deoxycholate agar. A single medium for the isolation of sodium and non-sodium dependent enteric gram-negative bacilli

Salt dependent gram-negative bacilli responsible for gastroenteritis and tissue infections are often not recovered because proper media for isolation are not used. A salt-starch XLD agar with 1.5% NaC1 and 0.5% starch medium has been found to permit the isolation of pathogenic Enterobacteriaceae, non-Enterobacteriaceae gram-negative bacilli, and salt-dependent gram-negative bacilli, among which is Vibrio parahemolyticus. As far as the Enterobacteriaceae are concerned, the selectivity and sensitivity of the medium are the same as with standard media with the added advantage of isolating salt-dependent organisms, thereby saving time and money. It can be used for routine blood cultures, investigation of sea water, seafood and tissue infections related to marine activities.

Vibrio alginolyticus infections in Hawaii

Clinical and bacteriological features of eight cases of Vibrio alginolyticus infections in Hawaii are presented. These isolates occurred in superficial sites, primarily related to infections caused by swimming.

Toxin isolation from a Kanagawa-phenomenon negative strain of Vibrio parahaemolyticus

Production of a toxin by Vibrio parahaemolyticus Kanagawa-phenomenon negative strains was examined. Ammonium sulfate fractions of broth culture filtrates were dialyzed, concentrated by lyophilization, and tested for toxic effects by mouse intraperitoneal injection. One fraction, which we think is a toxin, was isolated from a broth culture filtrate of V. parahaemolyticus FC 1011 (a Kanagawa-phenomenon negative strain) and consitently produced lethal effects in mice at high concentrations and diarrhea in lower concentrations. The toxin was assayed for mouse LD50 and ability to produce diarrhea via forced feeding in mice. V. parahaemolyticus FC 1011 toxin was found to be protein, to be inactivated by heat or trypsin hydrolysis, and to produce positive skin permeability reactions in rabbits. However, it failed to induce fluid accumulation in ligated ileal loops in rabbits.

Vibrio parahaemolyticus gastroenteritis associated with international travel

Food-borne gastroenteritis due to Vibrio parahaemolyticus is becoming of increasing world importance. This paper describes the clinical presentations and laboratory investigations of four cases of gastroenteritis due to V. parahaemolyticus among passengers returning to Australia on international aircraft from South-East Asia.

Isolation of Vibrio parahaemolyticus from fecal specimens on mannitol salt agar

Unless laboratories use an inhibitory medium, Vibrio parahaemolyticus will be unrecognizable in fecal specimens. The use of a medium exclusively for vibrio isolation, such as thiosulfate-citrate-bile salts-sucrose agar (TCBS), however, may not be considered economically justified in the United States. The isolation and recognition of V. parahaemolyticus is reported on mannitol salt agar (MS), a medium which is used for fecal specimens here. Eight Kanagawa-positive and two of three Kanagawa-negative strains of V. parahaemolyticus grew as well on MS as on TCBS and better than on a representative enteric medium, Hektoen enteric agar (HE). Twenty-two fecal specimens from 16 noninfected individuals were inoculated with known quantities of V. parahaemolyticus, and recovery of these vibrios was assessed on TCBS, MS, and HE. Recovery of vibrios from MS and TCBS was similar when inoculum size was 10(3) colony-forming units/ml or greater. Recovery of vibrios from mixed culture was distinctly lower on HE. The colonial morphology of V. parahaemolyticus and several other bacteria on MS is illustrated.

Isolation and characterization of Vibrio parahaemolyticus from Cape Cod soft-shell clams (Mya arenaria)

Vibrio parahaemolyticus was isolated from soft-shell clams (Mya arenaria) taken from 10 different clamming areas on Cape Cod, Mass., during July and August 1972. Direct plating on thiosulfate-citrate-bile salts-sucrose agar was found to be superior to either direct plating on Vanderzant modified salt starch agar or enrichment with Trypticase soy broth containing 7% salt for isolation from clam samples. Morphological and biochemical characteristics of 33 isolates from 30 samples generally conform to those described for this organism in the literature, except for the production of acid from sucrose, lactose, and sorbitol. Six of the isolates were hemolytic on human blood agar plates, whereas all showed a negative Kanagawa phenomenon. Twenty of the 33 isolates reacted with pooled antisera to the K antigen; 15 of these reacted with 9 different specific K antisera, leaving 5 untypable. Ten of these 15 reacted with 4 different O antisera.