Persistence of cholera in the United States: isolation of Vibrio cholerae O1 from a patient with diarrhea in Maryland

Closed Genome Sequence of Vibrio cholerae O1 El Tor Inaba Strain A1552

Vibrio cholerae is a Gram-negative waterborne human pathogen and the causative agent of cholera. Here, we present the complete genome sequence of the seventh pandemic O1 biovar El Tor Inaba strain A1552 isolated in 1992. This clinical strain has served as an important model strain for studying cholera pathogenicity traits.

A study on the existence of Vibrio cholerae non-O1 in the river

OBJECTIVE

The aim of the present study is Vibrio cholerae non-O1 existing in river. Bacteria are known to inhabit all kinds of environment. Vibrionaceae is widely distributed in environmental water. Vibrio spp. have been identified as a cause of toxicity in fish and shellfish. One condition affecting the survival of pathogenic microorganisms in environmental water is the salt concentration, and they have been reported to inhabit brackish water. However, V. cholerae non-O1 has also been detected in fresh water, and its properties suggest that it can survive in river water.

METHODS

Sampling was performed 4 times at 4 points during a 5-month period from July to November at about 1-month intervals from the Sagami River in 1985. River water bacteria were identified, and V. cholera non-O1 isolated. I investigated the relationship between the bacterial flora in river water and the detection of V. cholerae non-O1.

RESULTS

There were significant differences in the composition of bacterial flora with and without the isolation of V. cholerae non-O1 (Chi-square test) (χ(2) = 24.70 > 22.0 (p = 0.005), df = 8). A correlation between changes in the composition of the river water bacterial flora and detection of V. cholerae non-O1 was identified.

CONCLUSION

Therefore, V. cholerae non-O1 exists in the river.

Genomic and phenotypic characterization of Vibrio cholerae non-O1 isolates from a US Gulf Coast cholera outbreak

Between November 2010, and May 2011, eleven cases of cholera, unrelated to a concurrent outbreak on the island of Hispaniola, were recorded, and the causative agent, Vibrio cholerae serogroup O75, was traced to oysters harvested from Apalachicola Bay, Florida. From the 11 diagnosed cases, eight isolates of V. cholerae were isolated and their genomes were sequenced. Genomic analysis demonstrated the presence of a suite of mobile elements previously shown to be involved in the disease process of cholera (ctxAB, VPI-1 and -2, and a VSP-II like variant) and a phylogenomic analysis showed the isolates to be sister taxa to toxigenic V. cholerae V51 serogroup O141, a clinical strain isolated 23 years earlier. Toxigenic V. cholerae O75 has been repeatedly isolated from clinical cases in the southeastern United States and toxigenic V. cholerae O141 isolates have been isolated globally from clinical cases over several decades. Comparative genomics, phenotypic analyses, and a Caenorhabditis elegans model of infection for the isolates were conducted. This analysis coupled with isolation data of V. cholerae O75 and O141 suggests these strains may represent an underappreciated clade of cholera-causing strains responsible for significant disease burden globally.

O1 and non-O1 Vibrio cholerae bacteremia produced by hemolytic strains

Vibrio cholerae are Gram-negative bacteria capable of producing serious infections. They are differentiated into O1 and non-O1 serogroups, depending on their ability to agglutinate with specific antiserum. In contrast to non-O1 V. cholerae, which are more prone to invading the bloodstream, V. cholerae O1 is rarely the cause of bacteremia. We describe 2 cases of O and non-O1 V. cholerae bacteremia in patients with hepatitis C virus cirrhosis. We postulate that the hemolytic properties of the isolates contributed to their virulence in immunocompromised hosts.

The role of seafood in bacterial foodborne diseases

Pathogenic bacteria, when present in marine seafood and in fresh cultured products, are usually found at fairly low levels, and where these products are adequately cooked, food safety hazards are insignificant. A few bacteria associated with faecal contamination of seafood continue to pose a large-scale health threat through seafood.

Cholera

Despite more than a century of study, cholera still presents challenges and surprises to us. Throughout most of the 20th century, cholera was caused by Vibrio cholerae of the O1 serogroup and the disease was largely confined to Asia and Africa. However, the last decade of the 20th century has witnessed two major developments in the history of this disease. In 1991, a massive outbreak of cholera started in South America, the one continent previously untouched by cholera in this century. In 1992, an apparently new pandemic caused by a previously unknown serogroup of V. cholerae (O139) began in India and Bangladesh. The O139 epidemic has been occurring in populations assumed to be largely immune to V. cholerae O1 and has rapidly spread to many countries including the United States. In this review, we discuss all aspects of cholera, including the clinical microbiology, epidemiology, pathogenesis, and clinical features of the disease. Special attention will be paid to the extraordinary advances that have been made in recent years in unravelling the molecular pathogenesis of this infection and in the development of new generations of vaccines to prevent it.

International dissemination of epidemic Vibrio cholerae by cargo ship ballast and other nonpotable waters

In 1991 and 1992, toxigenic Vibrio cholerae O1, serotype Inaba, biotype El Tor, was recovered from nonpotable (ballast, bilge, and sewage) water from five cargo ships docked in ports of the U.S. Gulf of Mexico. Four of these ships had taken on ballast water in cholera-infected countries; the fifth took on ballast in a noninfected country. Isolates examined by pulsed-field gel electrophoresis were indistinguishable from the Latin American epidemic strain, C6707; however, they differed significantly from the endemic Gulf Coast strain (VRL 1984), the sixth-pandemic strain (569-B), and a V. cholerae non-O1 strain isolated from a ship arriving from a foreign port. On the basis of our findings, the Food and Drug Administration recommended that the U.S. Coast Guard issue an advisory to shipping agents and captains requesting that ballast waters be exchanged on the high seas before entry of ships into U.S. ports.

Successful application of enzyme-labeled oligonucleotide probe for rapid and accurate cholera diagnosis in a clinical laboratory

Two cholera cases were diagnosed using an enzyme-labeled oligonucleotide probe (ELONP) hybridization test for detection of cholera toxin gene (ctx) in a clinical laboratory at Osaka Airport Quarantine Station. The ELONP test with suspicious colonies of Vibrio cholerae O1 grown on TCBS or Vibrio agar plates gave positive result for ctx within 3 hr. We also tried to apply the ELONP test for direct detection of ctx in their stool and their non-selective culture. Specimens from Case #1, which contained 5.9 x 10(5) CFU/g of V. cholerae O1 in the stool, cultured for 7-8 hr or longer in alkaline peptone water or Marine broth at 37C, became positive for ctx. On the other hand, specimens from Case #2, which contained 8.7 x 10(8) CFU/ml (of V. cholerae O1 in the stool), gave positive result in this stool itself without any further culture. These data suggest that the ELONP test provides successfully a more rapid and accurate means of identifying "toxigenic" V. cholerae O1 in a clinical laboratory.

Epidemiologic application of a standardized ribotype scheme for Vibrio cholerae O1

A standardized scheme of 27 different BglI ribotypes and subtypes of Vibrio cholerae O1 strains is proposed on the basis of data from 214 human and environmental strains isolated in 35 countries and 14 U.S. states over the past 60 years. The ribotype patterns obtained are reproducible and stable over time. Seven different but very similar ribotypes (1a to 1g) were observed among 16 strains of the classical biotype. Twenty ribotypes and subtypes were identified among 198 V. cholerae O1 strains of the El Tor biotype. Six different patterns were found among the strains causing the current seventh pandemic. Strains of ribotype 8 originated only in central African countries, while those of ribotype 3 originated mainly in Asia and the Pacific Islands. The most widely distributed strains were those of ribotype 6, which was subdivided into three very similar but still distinguishable subtypes. The present Latin American epidemic is caused by strains of ribotype 5. Strains of this ribotype were isolated from several other geographic locations but can be differentiated from the Latin American strains by other molecular methods. Strains associated with two documented environmental reservoirs exhibited three distinct ribotype patterns; those isolated from patients who ate food from the U.S. Gulf waters were all of ribotype 2, while the strains related to the northeast Australian rivers were of ribotypes 9 and 10. Nontoxigenic V. cholerae O1 strains originating in Latin America and the U.S. Gulf Coast did not form a specific cluster of ribotypes. Ribotyping in combination with other well-defined methods can assist in epidemiologic investigations, helping to trace the movement of strains and to identify their geographic origins.

Development of an enzyme-labeled oligonucleotide probe for the cholera toxin gene

An alkaline phosphatase-conjugated 30-mer oligonucleotide probe was developed to detect the cholera toxin gene (ctx) in Vibrio cholerae O1. For rapid identification, V. cholerae O1 was grown on selective agar (thiosulfate-citrate-bile salts agar) or in alkaline peptone water and organisms were transferred directly to nylon membranes. Lysis of cells, denaturation of DNA, neutralization, and hybridization were carried out on the membrane. These procedures required only 3 h for completion. The results of the hybridization test with 88 clinical and 20 environmental isolates agreed almost exactly with the results of the immunological tests (anti-cholera toxin antibody-sensitized latex agglutination tests). The specificity of the probe was also tested with strains of enterotoxigenic Escherichia coli, V. cholerae non-O1, and Vibrio mimicus.

Subtyping of Legionella pneumophila serogroup 1 isolates by small-fragment restriction endonuclease analysis

Whole cell DNA of Legionella pneumophila isolates was examined by small-fragment restriction endonuclease analysis (SF-REA). Fourteen serogroup 1 isolates from tap water in one hospital collected before and after eradication measures had been taken were compared with control strains of serogroup 1 and other serogroups that were not epidemiologically linked. DNA was digested with EcoRI and electrophoresed on polyacrylamide gels. The gel patterns were made visible by silver staining and analysed by direct visual comparison. All 15 epidemiologically unrelated strains of Legionella pneumophila serogroup 1 and of other serogroups exhibited different restriction fragment patterns. The isolates from the hospital could be clearly subdivided into two groups by SF-REA, suggesting that the hot water supply of the hospital was contaminated with two different strains. SF-REA performed on Legionella pneumophila serogroup 1 DNA enabled further subtyping of these organisms and thus appears to be a useful technique for investigating their epidemiology.

Genetic diversity among toxigenic and nontoxigenic Vibrio cholerae O1 isolated from the Western Hemisphere

Multilocus enzyme electrophoresis was used to examine genetic relationships among and between toxigenic and non-toxigenic isolates of Vibrio cholerae O1 obtained from patients and the environment in the US Gulf Coast and surrounding areas. A total of 23 toxigenic and 23 non-toxigenic strains were examined. All the toxigenic and 7 of the non-toxigenic strains had the same alleles at 16 enzyme loci, whereas the balance of the nontoxigenic strains had 9 distinct combinations of alleles. This study suggests that all of the toxigenic strains belong to a single clone, and that while some of the non-toxigenic isolates were related, most were of diverse origin.

Cholera enterotoxin production in Vibrio cholerae O1 strains isolated from the environment and from humans in Japan

Vibrio cholerae O1 strains isolated from various sources in Japan over the years 1977 through 1987 were examined to confirm the presence or absence of the cholera enterotoxin (CT) gene and production of CT and to determine the kappa-phage type. The CT gene was detected in none of 225 isolates from natural waters but was present in all of the 10 isolates from environmental waters implicated in domestic cholera cases, in 64 strains (26.6%) of the 241 isolates from imported seafoods, in 43 strains (95.6%) of the 45 isolates from domestic cholera cases, and in 119 strains (93.7%) of the 127 isolates from imported cholera cases. The results suggest that the CT gene-positive strains of V. cholerae O1 have been imported into Japan through seafoods and/or by travelers. Sporadic cholera cases have resulted in contamination of the surrounding environment, but the CT gene-positive strains may not have persisted in natural waters to serve as a reservoir for epidemic cholera. The commercially available VET-RPLA kit (a latex agglutination kit for immunological detection of CT) detected production of CT in all of the CT gene-positive strains, indicating that there was no silent CT gene in the test strains. There was a strong correlation between the kappa-phage type and the presence or absence of the CT gene, suggesting a significant clonal difference between CT gene-positive and -negative strains. Five CT gene-negative strains isolated from imported cholera cases (travelers with mild diarrhea) induced a considerable amount of fluid accumulation in rabbit and/or suckling mouse intestines, indicating production of an enterotoxic factor(s) other than CT.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular epidemiology of Vibrio cholerae in Hong Kong

We studied restriction fragment length polymorphism of the enterotoxin genes of isolates of Vibrio cholerae El Tor, indistinguishable by bacteriophage typing, which were collected in Hong Kong since 1978. Using this approach, we could distinguish indigenous and exogenous strains obtained from different sources and epidemiological settings.

The human pathogenic vibrios--a public health update with environmental perspectives

Pathogenic Vibrio species are naturally-occurring bacteria in freshwater and saline aquatic environments. Counts of free-living bacteria in water are generally less than required to induce disease. Increases in number of organisms towards an infective dose can occur as water temperatures rise seasonally followed by growth and concentration of bacteria on higher animals, such as chitinous plankton, or accumulation by shellfish and seafood. Pathogenic Vibrio species must elaborate a series of virulence factors to elicit disease in humans. Activities which predispose diarrhoeal and extraintestinal infections include ingestion of seafood and shellfish and occupational or recreational exposure to natural aquatic environments, especially those above 20 degrees C. Travel to areas endemic for diseases due to pathogenic Vibrio species may be associated with infections. Host risk factors strongly associated with infections are lack of gastric acid and liver disorders. Involvement of pathogenic Vibrio species in cases of diarrhoea should be suspected especially if infection is associated with ingestion of seafood or shellfish, raw or undercooked, in the previous 72 h. Vibrio species should be suspected in any acute infection associated with wounds sustained or exposed in the marine or estuarine environment. Laboratories serving coastal areas where infection due to pathogenic Vibrio species are most likely to occur should consider routine use of TCBS agar and other detection regimens for culture of Vibrio species from faeces, blood and samples from wound and ear infections.

Isolation of Vibrio cholerae from aquatic birds in Colorado and Utah

Vibrio cholerae was isolated from cloacal swabs and freshly voided feces collected from 20 species of aquatic birds in Colorado and Utah during 1986 and 1987. About 17% (198 of 1,131) fecal specimens collected from July 1986 through August 1987 contained the organism. Both O1 and non-O1 V. cholerae strains were isolated from the fecal specimens. Isolates from eight birds (representing five species) agglutinated in O group 1 antiserum. Supernatants of broth cultures from three isolates which typed as V. cholerae O1 serotype Ogawa gave reactions typical of cholera toxin when tested on Y-1 mouse adrenal cell cultures. Several serovars of non-O1 V. cholerae were isolated from the fecal specimens; serovar 22 was the most prevalent type. All non-O1 isolates were cytotoxic to Y-1 mouse adrenal cells. Only non-O1 V. cholerae was detected in water samples collected from the habitat of the birds. The results of this study suggest that aquatic birds serve as carriers and disseminate V. cholerae over a wide area.

A comparison of DNA and immunoblot fingerprinting of the SII biotype of coagulase negative staphylococci

Thirty-eight isolates of the SII biotype of coagulase negative staphylococci were examined by phase typing, antibiograms, DNA and immunoblot fingerprinting. Multiple isolates were available from 5 patients with clinically proven infections and from 12 further patients who were epidemiologically distinct. Only 3 of the isolates were phage typable and antibiograms produced only 9 types. All isolates were typable by both DNA and immunoblot fingerprinting and reproducibility was excellent provided the conditions were standardized. Discrimination was better with immunoblot fingerprinting (17 types) than DNA fingerprinting (11 types). Both techniques were successful in assessing the significance of multiple isolates from a single patient.

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.

Diagnostic deoxyribonucleic acid probes for infectious diseases

Virtually all microorganisms contain some unique nucleotide sequences which can be the target of deoxyribonucleic acid probes. Probes have been used successfully to identify a wide variety of pathogens from the simple ribonucleic acid-containing polioviruses to the complex filarial worms Brugia malayi. Probe technology offers the clinical laboratory the potential both to extend the types of pathogens that can be readily identified and to reduce significantly the time associated with the identification of fastidious microorganisms. Over a dozen commercially prepared deoxyribonucleic acid probe tests are now available. This article explores the development of deoxyribonucleic acid probe tests and reviews the sensitivity, specificity, and predictive values of many of the diagnostic probes developed during the last several years. Prospects for newer, more sensitive detection systems for the products of hybridization reactions are also reviewed.