German coasts harbor non-O1/non-O139 Vibrio cholerae with clinical virulence gene profiles

Non-O1/non-O139 Vibrio cholerae (NOVC) are ubiquitous in aquatic ecosystems. In rare cases, they can cause intestinal and extra-intestinal infections in human. This ability is associated with various virulence factors. The presence of NOVC in German North Sea and Baltic Sea was observed in previous studies. However, data on virulence characteristics are still scarce. Therefore, this work aimed to investigating the virulence potential of NOVC isolated in these two regions. In total, 31 NOVC strains were collected and subjected to whole genome sequencing. In silico analysis of the pathogenic potential was performed based on the detection of genes involved in colonization and virulence. Phenotypic assays, including biofilm formation, mobility and human serum resistance assays were applied for validation. Associated toxin genes (hlyA, rtxA, chxA and stn), pathogenicity islands (Vibrio pathogenicity island 2 (VPI-II) and Vibrio seventh pathogenicity island 2 (VSP-II)) and secretion systems (Type II, III and VI secretion system) were observed. A maximum likelihood analysis from shared core genes revealed a close relationship between clinical NOVCs published in NCBI and environmental strains from this study. NOVC strains are more mobile at 37 °C than at 25 °C, and 68% of the NOVC strains could form strong biofilms at both temperatures. All tested strains were able to lyse erythrocytes from both human and sheep blood. Additionally, one strain could survive up to 60% and seven strains up to 40% human serum at 37 °C. Overall, the genetic virulence profile as well as the phenotypic virulence characteristics of the investigated NOVC from the German North Sea and Baltic Sea suggest potential human pathogenicity.

Interspecies interactions of non-O1/O139 Vibrio cholerae and Salmonella typhimurium: a rare coinfection case report

Infectious diseases are commonly demonstrated to be caused by polymicrobial infections, which correlate with increased infection severity and poorer clinical outcomes. In this study, we report a rare intestinal coinfection case of non-O1/O139 Vibrio cholerae and Salmonella typhimurium, along with V. cholerae septicemia. The data of quantitative real-time PCR and competition assay showed that V. cholerae may present enhanced virulence in the presence of S. typhimurium, and exerted an inhibitory growth effect over S. typhimurium in vitro.

Bacteremia by non-O1/non-O139 Vibrio cholerae: Case description and literature review

Bacteremia by non-O1/non-O139 Vibrio cholerae is a rare entity associated with high mortality rates. We report a case of non-O1/non-O139 V. cholerae bacteremia confirmed by polymerase chain reaction and agglutination tests. The clinicoepidemiological characteristics and therapeutic options for this infection are also described.

Bacteremia Caused by a Serotype Ob5 Vibrio cholerae Strain in a Cirrhotic Patient in China

The increasing incidence of non-O1/non-O139 Vibrio cholerae (NOVC) has been observed worldwide. However, septicemia caused by NOVC remains a rare condition that has received limited attention. Currently, there are no established treatment guidelines for bloodstream infections caused by NOVC, and the understanding of this condition mainly relies on individual case reports. Although NOVC bacteremia can be fatal in a small percentage of cases, knowledge about its microbiological features remains limited. Here, we present a case of V. cholerae septicemia caused by NOVC in a 46-year-old man with chronic viral hepatitis and liver cirrhosis. The isolated strain, named V. cholerae VCH20210731 and classified as a new sequence type (ST), ST1553, was found to be susceptible to most of the antimicrobial agents tested. O-antigen serotyping of V. cholerae VCH20210731 revealed that it belonged to serotype Ob5. Interestingly, the ctxAB genes, which are typically associated with V. cholerae, were absent in VCH20210731. However, the strain possessed 25 other potential virulence genes, such as hlyA, luxS, hap, and rtxA. The resistome of V. cholerae VCH20210731 included several genes, including qnrVC4, crp, almG, and parE. Nevertheless, susceptibility testing demonstrated that the isolate was susceptible to most of the antimicrobial agents tested. Phylogenetic analysis indicated that the closest strain to VCH20210731 was strain 120 from Russia, differing by 630 single-nucleotide polymorphisms (SNPs). Our findings contribute to the understanding of the genomic epidemiological characteristics and antibiotic resistance mechanisms of this invasive bacterial pathogen. IMPORTANCE This study highlights the discovery of a novel ST1553 V. cholerae strain in China, providing valuable insights into the genomic epidemiology and global transmission dynamics of V. cholerae. It is important to note that clinical presentations of NOVC bacteremia can vary significantly, and the isolates demonstrate genetic diversity. Consequently, health care professionals and public health experts should remain vigilant about the potential for infection with this pathogen, particularly considering the elevated prevalence of liver disease in China.

Clinical and Environmental Vibrio cholerae Non-O1, Non-O139 Strains from Australia Have Similar Virulence and Antimicrobial Resistance Gene Profiles

Cholera caused by pathogenic Vibrio cholerae is still considered one of the major health problems in developing countries including those in Asia and Africa. Australia is known to have unique V. cholerae strains in Queensland waterways, resulting in sporadic cholera-like disease being reported in Queensland each year. We conducted virulence and antimicrobial genetic characterization of O1 and non-O1, non-O139 V. cholerae (NOVC) strains (1983 to 2020) from Queensland with clinical significance and compared these to environmental strains that were collected as part of a V. cholerae monitoring project in 2012 of Queensland waterways. In this study, 87 V. cholerae strains were analyzed where O1 (n = 5) and NOVC (n = 54) strains from Queensland and international travel-associated NOVC (n = 2) (61 in total) strains were sequenced, characterized, and compared with seven previously sequenced O1 strains and 18 other publicly available NOVC strains from Australia and overseas to visualize the genetic context among them. Of the 61 strains, three clinical and environmental NOVC serogroup strains had cholera toxin-producing genes, namely, the CTX phage (identified in previous outbreaks) and the complete Vibrio pathogenicity island 1. Phylogenetic analysis based on core genome analysis showed more than 10 distinct clusters and interrelatedness between clinical and environmental V. cholerae strains from Australia. Moreover, 30 (55%) NOVC strains had the cholix toxin gene (chxA) while only 11 (20%) strains had the mshA gene. In addition, 18 (34%) NOVC strains from Australia had the type three secretion system and discrete expression of type six secretion system genes. Interestingly, four NOVC strains from Australia and one NOVC strain from Indonesia had intSXT, a mobile genetic element. Several strains were found to have beta-lactamase (blaCARB-9) and chloramphenicol acetyltransferase (catB9) genes. Our study suggests that Queensland waterways can harbor highly divergent V. cholerae strains and serve as a reservoir for various V. cholerae-associated virulence genes which could be shared among O1 and NOVC V. cholerae strains via mobile genetic elements or horizontal gene transfer. IMPORTANCE Australia has its own V. cholerae strains, both toxigenic and nontoxigenic, that are associated with cholera disease. This study aimed to characterize a collection of clinical and environmental NOVC strains from Australia to understand their virulence and antimicrobial resistance profile and to place strains from Australia in the genetic context of international strains. The findings from this study suggest the toxigenic V. cholerae strains in the Queensland River water system are of public health concern. Therefore, ongoing monitoring and genomic characterization of V. cholerae strains from the Queensland environment are important and would assist public health departments to track the source of cholera infection early and implement prevention strategies for future outbreaks. Understanding the genomics of V. cholerae could also inform the natural ecology and evolution of this bacterium in natural environments.

Population Structure and Multidrug Resistance of Non-O1/Non-O139 Vibrio cholerae in Freshwater Rivers in Zhejiang, China

To understand the environmental reservoirs of Vibrio cholerae and their public health significance, we surveyed freshwater samples from rivers in two cities (Jiaxing [JX] and Jiande [JD]) in Zhejiang, China. A total of 26 sampling locations were selected, and river water was sampled 456 times from 2015 to 2016 yielding 200 V. cholerae isolates, all of which were non-O1/non-O139. The average isolation rate was 47.3% and 39.1% in JX and JD, respectively. Antibiotic resistance profiles of the V. cholerae isolates were examined with nonsusceptibility to cefazolin (68.70%, 79/115) being most common, followed by ampicillin (47.83%, 55/115) and imipenem (27.83%, 32/115). Forty-two isolates (36.52%, 42/115) were defined as multidrug resistant (MDR). The presence of virulence genes was also determined, and the majority of the isolates were positive for toxR (198/200, 99%) and hlyA (196/200, 98%) with few other virulence genes observed. The population structure of the V. cholerae non-O1/non-O139 sampled was examined using multilocus sequence typing (MLST) with 200 isolates assigned to 128 STs and 6 subpopulations. The non-O1/non-O139 V. cholerae population in JX was more varied than in JD. By clonal complexes (CCs), 31 CCs that contained isolates from this study were shared with other parts of China and/or other countries, suggesting widespread presence of some non-O1/non-O139 clones. Drug resistance profiles differed between subpopulations. The findings suggest that non-O1/non-O139 V. cholerae in the freshwater environment is a potential source of human infections. Routine surveillance of non-O1/non-O139 V. cholerae in freshwater rivers will be of importance to public health.

Virulence-associated factors in Vibrio cholerae non-O1/non-O139 and V. mimicus strains isolated in ornamental fish species

During recent decades, ornamental fish have proven to be one of the fastest growing categories of pets in Europe. In this framework, we evaluated both the potential pathogenic and zoonotic risks caused by 53 Vibrio cholerae non-O1/non-O139 and a Vibrio mimicus strain isolated from ornamental fish species mostly originating from South-East Asia countries between 2000 and 2015 in Italy. All the strains were firstly identified at species level by biochemical, phylogenetic and mass spectrometry (matrix-assisted laser desorption ionization time of flight) methods, and then studied to reveal the presence of the main virulence and colonization-associated factors, as ctxA, ace, zot, stn/sto, toxR, rtxA, hlyA and tcpA by multiplex and single endpoint PCR assays. Findings showed that 21 of 54 strains harboured at least one virulence factor with a predominance for the toxR⁺ , rtxA⁺ and hlyAET⁺ genotype. Interestingly, the V. mimicus strain harboured the colonization factor and the CTX prophage receptor, tcpA, indicating the ability to capture and integrate it in its genome increasing its pathogenicity. Although these enterotoxins can sporadically cause gastroenteritis, the results highlight their probable involvement in causing severe implications for public health, suggesting the need for an European microbiological monitoring.

Environmental Vibrio cholerae non O1/ non O139 from the Gangetic delta: a diarrhoeal disease purview

Diarrhoea still remains an unsolved enigma in developing countries, a major concern for the health planners. We targeted the abundance and toxicity of Vibrio cholerae non-O1/non-O139 (NOVC) in Gangetic riverine-estuarine ecosystem. A total of 74 V. cholerae were isolated from 120 water samples (68 NOVC, 6 V. cholerae O1) from two sampling sites off river Ganges. V. cholerae showed distinct seasonality, with steady increase from summer to monsoon, steep ascent in post-monsoon and an abrupt decline in winter. Highest number of NOVC was isolated form Howrah, attributed to low salinity and high anthropogenic influence. Environmental NOVC harboured hlyA (94.0 %), rtxA (81.0 %) and toxR (28.0 %) genes. About 23.4 % of the hlyA harbouring NOVC showed haemolytic activity. Accessory toxin genes (tlcR, toxT, RJ and LJ and aldA), among 3-5 % of the NOVC carry significant health implications. Haemolytic activity and biofilm formation in NOVC, during unfavourable conditions, facilitates gene transfer and emphasises the role of environmental NOVC in diarrhoeal incidence in South Bengal, India.

[N-ACETYL-β-D-GLUCOSAMINIDASE OF VIBRIO CHOLERAE]

AIM

Study N-acetyl-β-D-glucosaminidase (chitobiase) (EC 3.2.1.30) in strains of Vibrio cholerae of O1/non-O1 serogroups of various origin, that is a component of chitinolytic complex taking into account object of isolation and epidemiologic significance of strains.

MATERIALS AND METHODS

Cultures of V. cholerae O1/non-O1 serogroup strains were obtained from the museum of live culture of Rostov RIPC. Enzymatic activity analysis was carried out in Hitachi F-2500 fluorescent spectrophotometer using FL Solutions licensed software. NCBI databases were used during enzyme characteristics.

RESULTS

N-acetyl-β-D-glucosaminidase in Vcholerae O1/non-O1 serogroup strains was detected, purified by column chromatography, studied and characterized by a number of physical-chemical and biological properties. Comparative computer analysis of amino acid sequence of N-acetyl-β-D-glucosaminidases of V. cholerae (VC2217 gene), Serratia marcescens etc. has allowed. to attribute the enzyme from V. cholerae to glycosyl-hydrolases (chitobiases) of family 20 and classify it according to enzyme nomenclature as EC 3.2.1.30.

CONCLUSION

N-acetyl-β-D-glucosaminidase in V. cholerae of O1/non-O1 serogroups of various origin and epidemiologic significance, participating in chitin utilization was studied and characterized for the first time, and its possible role in biology of cholera causative agent was shown.

[TYPING OF VIBRIO CHOLERAE NON O1/NON O139 STRAINS, ISOLATED IN ROSTOV REGION IN 2014]

AIM

Comparative study of antibiotics resistance and VNTR-typing of Vibrio cholerae non O1/ non O139 strains, isolated on the territory of Rostov region in 2014.

MATERIALS AND METHODS

Antibioticogramms of strains were determined by serial dilution method in dense nutrient medium according to MG 4.2.2495-09 (2009). Pheno-, sero- and VNTR-typing was carried out by conventional-methods.

RESULTS

The studied strains belonged to V. cholerae species, did not agglutinate with O1 and O139 sera, were atoxigenic hemolysis-positive, did not contain genes of cholera toxin and toxin-coregulating pili of adhesion, contained genes of hemagglutinin/protease, protease PrtV, collagenase, cytotonic factor Cef, outer membrane protein-OmpW, tol- and -vps-clusters, regulatory genes toxR and hapR. Antibioticogramms of the strains have shown the presence of cultures, resistant to ampicillin, ceftazidime-furazolidone, trimethoprim/sulfamethoxazole with intermediate resistance to streptomycin, kanamycin, gentamycin, amikacin, netilmicin, Approximately 20% of isolates had multiple drug resistance. Data of VNTR- and genotyping confirmed a possibility of water transmission route of the infection.

CONCLUSION

Execution of monitoring of cultures from environmental samples is necessary for timely detection of genetic characteristics, antibiotics resistance.

GENOTYPE AND DRUG RESISTANCE OF CLINICAL AND ENVIRONMENTAL VIBRIO CHOLERAE NON-O1/NON-O139 IN NORTHEASTERN THAILAND

A total of 124 V cholerae non-O1/non-O139 isolates were collected in Khon Kaen, Thailand from diarrheal patients, asymptomatic carriers and environmental water. The presence of virulence-associated and regulatory genes including ctxA, tcpA, zot, ace, ompU, stn, hlyA and toxR) were examined using multiplex PCR. The genomic diversity of the various V. cholerae isolates were differentiated using the random amplified polymorphic DNA (RAPD) method. Antimicrobial susceptibility was tested using disk diffusion. All of V. cholerae non-O/non-O139 isolates carried hlyA and toxR and none carried ctxA and tcpA. The zot, ace and both genes together were found in 1.6%, 4.7% and 4.7% of 64 clinical V. cholerae non-O1 isolates, respectively, while the environmental ones did not. The stn gene was found in 3.1% (2/64) of the clinical and 3.3% (2/60) of the environmental isolates. The RAPD patterns were differentiated into 45 types (A to 2S). RAPD type A (32.3%) was the most frequently found in both clinical and environmental V cholerae non-O1 strains (34.4% and 30.0%, respectively); indicating that there was a clonal relationship between some clinical and environmental isolates whereas almost all of the environmental isolates belonged to different clones. All strains were sensitive to ciprofloxacin and norfloxacin. The environmental isolates (30%) were more resistant than the clinical ones (21.9%). Resistance to sulfamethoxazole/trimethoprim and tetracycline among the clinical isolates occurred in 9.4% (6/64) in 2007, during which period the prevalence of V cholerae O1 increased. We conclude that V. cholerae non-O1/non-O139 from the aquatic environment are potentially pathogenic and this same aquatic environment may be a source of antimicrobial resistance in V. cholerae.

ROLE OF HLYA-POSITIVE VIBRIO CHOLERAE NON-O1/NON-O139 ON APOPTOSIS AND CYTOTOXICITY IN A CHINESE HAMSTER OVARY CELL LINE

Vibrio cholerae non-O1/non-O139 is capable of producing sporadic outbreaks of cholera-like diarrhea; however, the pathogenic mechanisms of this bacterium remain unclear. The objectives of this study were to: 1) compare the apoptosis induction and cytotoxicity between hlyA-positive and hlyA-negative strains of V. cholerae non-O1/non-O139; 2) clarify the molecular mechanisms by which these strains induce apoptosis; and 3) compare clinical and environmental V. cholerae non-O1/non-O139 isolates with respect to cytotoxicity and ability to induce apoptosis. Using cytotoxicity and apoptosis assays, it was shown that hlyA-positive strains of V. cholerae non-O1/non-O139 had significantly higher cytotoxic activity (70.6%) and levels of apoptosis induction (59.6%) than hlyA- negative strains (37.0% and 37.5%, respectively). Western blot analyses revealed that hlyA-positive strains had significantly increased expression of Bax; active caspase-3 and -9; and significantly decreased expression of NF-κB and Bcl-2 relative to hlyA-negative strains. Expression of BID did not differ significantly between hlyA-positive and negative strains. The truncated BID was not found, indicating that V. cholerae non-O1/non-O139 induces apoptosis through a mitochondria- dependent apoptosis pathway and not an extrinsic pathway. V. cholerae non-O1/ non-O139 isolated from clinical sources exhibited significantly higher cytotoxic activity (79%) and levels of apoptosis induction (65.2%) than bacteria isolated from environmental sources (63% and 54.6%, respectively), suggesting that the clini- cal isolates may have other virulence-associated genes besides hlyA. Our results indicate that hlyA products play a role in cytotoxicity and apoptosis induction and that a mitochondria-dependent apoptosis pathway is involved.

[Development of both multiple PCR and real-time SYBR green PCR for the detection of Vibrio cholerae non-O1/O139 serogroups]

OBJECTIVE

To develop methodology of both multiple PCR and real-time SYBR green PCR for the detection of Vibrio cholerae (V. cholerae) serogroups non-O1 and non-O139.

METHODS

The outer membrane protein gene (ompW) specific for V. cholerae, as well as O antigen rfb genes specific for both O1 and O139, were used for the design of the PCR primers. Both multiple PCR and real-time SYBR green PCR systems were used to detect both O1 and O139. Specific rfb genes and ompW were developed to evaluate their specificity, limit of detection, reproducibility and consistency.

RESULTS

We established multiple PCR and real-time SYBR green PCR methods. According to the specific electrophoretic bands (multiple PCR) and the specific melt curve temperature (real-time SYBR green PCR), both methods could specifically detect the non-O1, non-O139 V. cholerae, and to differentiate them from O1,O139 V. cholerae, other five Vibrios and 3 intestinal bacteria. The detection limits were 7 × 10(4) cfu/ml (multiple PCR) and 7 × 10² cfu/ml(real-time SYBR green PCR), with statistically significant difference seen (P < 0.05). For the reproducibility of real-time SYBR green PCR, the external coefficient variation ranging from 0.22% to 0.92% while the internal coefficient variation ranging from 0.27% to 1.41%. 370 strains of non-O1, non-O139 V. cholerae, were detected, with both consistency rates as 100% .

CONCLUSION

Both multiple PCR and real-time SYBR green PCR could detect non-O1, non-O139 V. cholerae, rapidly, specifically, and reproducibly, that could all be used for the detection and identification of non-O1, non-O139 under different conditions.

[Antibiotic Susceptibility of Vibrio cholerae non O1/non O139 Serogroups Isolated from Environment in the Rostov Region]

Analysis of the antibioticograms of 22 strains of Vibrio cholerae non O1/non O139 serogroups (ctxA- tepA-) isolated from the environment in the Rostov Region in 2011 showed that all the cultures were susceptible to ciprofloxacin, aminoglycosides, ceftriaxone, trimetoprime/sulfamethoxazole and resistant to levomycetin and furazolidone. 32%, 18% and 9% of the isolates were resistant to tetracycline, rifampicin and nalidixic acid respectively. No strains of V. cholerae susceptible to all the tested antimicrobials were detected. 37% of the V. cholerae isolates was resistant to two antibacterials and the others showed multiple resistance and contained 3-6 r-determinants of antibiotic resistance. Since the antibiotic resistance genes in Vibrio cholerae non O1/non O139 serogroups are often located on mobile genetic elements (plasmids, interferons, SXT elements), many strains of such organisms, the same as the natural environment, could serve as reservoirs of antibiotic resistance. The presence of antibiotic resistance r-determinants in the investigated strains in various combinations, the antibiotic resistance variability in the isolates collected on the same territory within a relatively short period of time require monitoring of antibiotic susceptibility in them and the use of the antibiotic for the etiotropic therapy only in strict accordance with the antibioticogram of the culture isolated from the concrete patient.

[Genetic characterization of toxigenic Vibrio cholerae non-O1/non-O139 strains, isolated in the Middle Asia]

Here, we report the characterization of 22 clinical toxigenic V. cholerae non-O1/non-O139 strains isolated in the Middle Asia (Uzbekistan) in 1971-1990. PCR analysis has revealed that these strains contain the main virulence genes such as ctxA, zot, ace (CTXφ); rstC (RS1φ); tcpA, toxT, aldA (pathogenicity island VPI), but they lack both pandemic islands VSP-I and VSP-II specific to epidemic strains of O1 serogroup of El Tor biotype and O139 serogroup. Only two of the twenty two toxigenic strains have tcpA gene of El Tor type, one strain has tcpA gene of classical type, while nineteen other strains carry a new variant of this gene, designated as tcpA(uzb).. Nucleotide sequences analysis of virulence genes in toxigenic V. cholerae non-O1/non-O139 strains from Uzbekistan showed that they differ significantly from the sequences of these genes in epidemic O1 and O139 strain indicating that they belong to a separate line of evolution of virulent V. cholerae strains. For the first time it is shown that V. cholerae non-O1/non-O139 toxigenic strains of different serogroups may belong to the same clone.

[Acute gastroenteritis caused by a Vibrio cholerae non-O1, non-O139 strain harboring a genetic region homologous to the VpaI-7 pathogenicity island]

Pathogenic Vibrio cholerae isolates, the etiologic agents of cholera, generally express one of two O antigens (O1 or O139). Most environmental isolates are nonpathogenic and are referred to as "non-O1, non-O139". However some V. cholerae non-O1, non-O139 strains are clearly pathogenic and have caused outbreaks or sporadic cases of gastroenteritis and extraintestinal infections in humans. We report a case of acute gastroenteritis by a V. cholerae non-O1, non-O139 harboring a genetic region homologous to a segment of the VpaI-7 V. parahaemolyticus pathogenicity island.

[Characteristics of Vibrio cholerae nonO1/nonO139 serogroup strains that caused diseases in population of Rostov region]

AIM

Genotype characteristic and determination of serological properties of Vibrio cholerae nonO1/nonO139 strains that caused diseases in population of Rostov region from 2000 to 2009.

MATERIALS AND METHODS

15 clinical strains of V. cholerae nonO1/nonO139 were studied. Serotyping was performed by using a kit of monospecific typing sera against serogroup 02-084 cholera vibrios obtained from Rostov Research Institute for Plague Control, PCR and VNTR-genotyping--by using specific primers described in scientific publications and constructed by us.

RESULTS

Serologic features of strains are very diverse and strains contain various combination of pathogenicity factor genes that seem to be interchangeable. Similar pattern was observed for VNTR-genotyping. Distribution of the examined strains by VNTR-genotyping did not correlate with either PCR-genotyping data or serotyping, or place and time of isolation.

CONCLUSION

The data obtained indicates a lack of general source of human infection even in the same location and time period. On the other hand, serological and genotypic features of V. cholerae nonO1/nonO139 may undergo changes in the process of staying in the macro organism or environment due to high plasticity of their genome.

[Serotyping and genotypic characteristic of Vibrio cholerae non-O1/non-O139 serogroups isolated from water of surface basins and sewages of Rostov-on-Don city in 2003 - 2008]

AIM

Determination of serogroup and PCR-genotyping of Vibrio cholerae non-O1/non-O139 strains isolated from surface basins and sewages of Rostov-on-Don city in 2003 - 2008.

MATERIALS AND METHODS

Seven hundred strains of V. cholerae non-O1/non-O139 serogroups were studied in reaction of slide-agglutination with array of 80 diagnostic sera for non-O1/non-O139 serogroups. Selective screening of strains representing dominating serogroups was performed for extended number of genetic determinants of pathogenicity factors.

RESULTS

It was established that V. cholerae belonging to serogroups O53, O67, O75, and O76 are dominating in water ecosystems of Rostov-on-Don city at this time. All studied strains were characterized by lack of cholera toxin genes and toxin-coregulated pili but had different combinations of genes of additional virulence factors. There was no correlation between genotypic characteristics and serogroup.

CONCLUSION

The study showed that change of serologic landscape of V. cholerae non-O1/non-O139 occurred in water objects in studied area during last decades. Necessity of dynamic surveillance for circulation of V. cholerae non-O1/non-O139 in aquatic environment with widening of studied spectrum of their biological features was demonstrated.

Non-O1, non-O139 Vibrio cholerae bacteraemia in splenectomised thalassaemic patient from Malaysia

Vibrio cholerae infection is mainly caused acute diarrhoea disease. Bacteraemia due to non-O1 V. cholerae is rare and mainly reported in liver cirrhotic patients. We report one case of non-O1 V. cholerae bacteraemia in splenectomised thalassaemic patient who presented with septic shock secondary to abdominal sepsis. She had undergone emergency laporatomy and was managed in the intensive care unit for nine days. She was treated with meropenem and doxycyline and discharged well after fourteen days of admission. The V. cholerae was identified by API 20NE, serotype and polymerase chain reaction showed as non-O1, non-O139 strain. Besides known cholera-like toxin and El Tor hemolysin, with increasing reported cases of V. cholerae bacteraemia, there is possibility of other virulence factors that allow this organism to invade the bloodstream.

[Non-toxigenic hemolytic Vibrio cholerae non-O1 non-O139 fatal septicemia. Report of one case]

We report a 70-year-old woman, who had recently consumed shellfish, that was admitted to the intensive care unit with septic shock and died 19 hours later due to a multi-organic failure. Microbiological, serological and molecular assays confirmed a hemolytic tdh+ Vibrio cholerae non-01, non 0139 as the etiologic agent.

[Characterization of Vibrio cholerae non-O1 and non-O139 isolates associated with diarrhea]

Vibrio cholerae, etiologic agent of cholera, is transmitted to humans by ingestion of contaminated food or water. Even though serogroups O1 and O139 are the ones usually associated to epidemic cholera, isolates from other serogroups also cause gastroenteritis and extraintestinal infections. During the period 2003-2005, presence of V. cholerae in stools was investigated in children with diarrhea that seaked assistance at the Niño Jesús Hospital in Tucumán. Thirty four isolates of V. cholerae non-O1, non-O139 were recovered. We characterized the isolates studying its virulence factors by PCR, antimicrobial susceptibility patterns and genetic diversity by pulsed-field gel electrophoresis. Eight virulence patterns were obtained although no isolate was positive for the cholera toxin or the thermostable toxin. Four isolates were positive for the type three secretion system. The 17.6% of the isolates were resistant or intermediate to ampicillin and 5.9% were resistant to trimethoprim-sulfamethoxazole. By Sfil-PFGE, all isolates were genetically very diverse, as 27 different patterns were identified in 29 typeable isolates by pulsed-field gel electrophoresis. Although it has a low incidence, V. cholerae continues to be a causative agent of diarrhea in children, who are affected by a variety of circulating strains of V. cholerae non-O1, non-O139.

Association of ompU gene in Vibrio cholerae from patients and environment with bile resistance

The objective of this study was to determine whether Vibrio cholerae, possessing ompU isolated from patients and the environment, conferred bile resistance and whether other virulence genes were also related to bile resistance. Fifty-two V cholerae O1 and non-O1 isolates were examined by PCR for the presence of the virulence-associated and regulatory genes, ctxA, tcpA, zot, ace, ompU, toxR, hlyA and stn/sto. V. cholerae possessing ompU resistant to equal or greater than 10% sodium deoxycholate were found in 93% of isolates but only in 9% of V. cholerae isolates not possessing ompU. The effects of other virulence genes on bile resistance could not be ascertained in this study. Thus V cholerae non-O1 with ompU and possibly other virulence genes isolated from the environment have the potential of affecting public health.

Seasonal cholera from multiple small outbreaks, rural Bangladesh

Clinical and environmental Vibrio cholerae organisms collected from February 2004 through April 2005 were systematically isolated from 2 rural Bangladeshi locales. Their genetic relatedness was evaluated at 5 loci that contained a variable number of tandem repeats (VNTR). The observed minimal overlap in VNTR patterns between the 2 communities was consistent with sequential, small outbreaks from local sources.

Clinical characteristics of non-O1/non-O139 Vibrio cholerae isolates and polymerase chain reaction analysis of their virulence factors

BACKGROUND AND PURPOSE

Non-O1/non-O139 Vibrio cholerae can cause invasive extraintestinal disease as well as enteritis. The pathogenesis of invasive non-O1/non-O139 V. cholerae infections remains to be determined. This study compared the clinical manifestations and predisposing factors between bacteremic and non-bacteremic non-O1/non-O139 V. cholerae infections and examined virulence-associated genes in the pathogenic strains causing invasive disease.

METHODS

We retrospectively investigated clinical characteristics of 18 bacteremic patients and 18 non-bacteremic patients, including demographic, laboratory and clinical data. Fourteen clinical isolates (ten isolated from blood and four from stool specimens) were obtained for polymerase chain reaction tests of the presence of virulence-associated genes ctxA, ctxB and tcpA.

RESULTS

There was no difference in age, gender and gastrointestinal symptoms including abdominal pain and diarrhea, laboratory findings including leukocytosis and anemia, or underlying immunocompromised condition, except cirrhosis, between the bacteremic and non-bacteremic groups. Compared to patients with non-bacteremic infections, patients with non-O1/non-O139 V. cholerae bacteremia were significantly more likely to have cirrhosis and thrombocytopenia (0.0% vs 77.8% and 5.9% vs 72.2%, respectively; p<0.001). The cholera toxin genes (ctxA and ctxB) were found in only one strain (isolated from the stool specimen of a patient with enteritis) among fourteen clinical strains (7%). The tcpA gene, encoding the toxin-coregulated pilus, was present in thirteen of fourteen isolates (93%) [including ten isolates from blood, and three isolates from stool specimens].

CONCLUSIONS

Cirrhotic patients with thrombocytopenia were vulnerable to non-O1/non-O139 V. cholerae bloodstream invasion. The low prevalence of ctxA and ctxB genes in stool specimens indicates other toxins could have contributed to diarrhea. The fact that the tcpA gene was highly prevalent in clinical isolates in this study could imply an important role of tcpA in the pathogenesis of invasive disease caused by non-O1/non-O139 V. cholerae.

[Molecular-epidemiological characteristic and possible origin of Vibrio cholerae non O1/non O139 with complete and limited set of virulence genes]

Study of molecular-epidemiological characteristics of Vibrio cholerae non O1/non O139 serogroup with complete and limited set of virulence genes was performed. Differences of their genes composition as compared to these of O1 serogroup (classic and El Tor biovars) were revealed, which points to their origin from avirulent environmental cholera vibrios.

Single multiplex polymerase chain reaction for environmental surveillance of toxigenic-pathogenic O1 and non-O1 Vibrio cholerae

A multiplex PCR assay was developed for the detection of toxigenic and pathogenic V. cholerae from direct water sources using specific primers targeting diverse genes, viz. outer membrane protein (ompW), cholera toxin (ctxB), ORF specific for O1 (rfbG), zonula occludens (zot) and toxin co-regulated pilus (tcpB); among these genes, ompW acts as internal control for V. cholerae, the ctx gene as a marker for toxigenicity and tcp for pathogenicity. The sensitivity of multiplex PCR was 5 x 10(4) V. cholerae cells per reaction. The procedure was simplified as direct bacterial cells were used as template and there was no need for DNA extraction. The assay was specific as no amplification occurred with the other bacteria used. Toxigenic V. cholerae were artificially spiked in different water samples, filtered through a 0.45 microm membrane, and the filters containing bacteria were enriched in APW for 6 h. PCR following filtration and enrichment could detect as little as 8 V. cholerae cells per mL in different spiked water samples. Various environmental potable water samples were screened for the presence of V. cholerae using this assay procedure. The proposed method is rapid, sensitive and specific for environmental surveillance for the presence of toxigenic-pathogenic and nonpathogenic V. cholerae.

The genome of non-O1 Vibrio cholerae NRT36S demonstrates the presence of pathogenic mechanisms that are distinct from those of O1 Vibrio cholerae

Vibrio cholerae NRT36S is a non-cholera toxin-producing, non-O1 strain that causes diarrhea in volunteers. The genome of NRT36S was sequenced to create a draft containing 174 contigs plus the superintegron region. Our analysis of the draft genome revealed several putative toxin genes and colonization factors. Besides confirming the existence of nonagglutinable heat-stable toxin, we also identified the genes for a type three secretion system, a putative exotoxin, two different RTX toxins, and four pilus systems.

Vibrio cholerae strain typing and phylogeny study based on simple sequence repeats

Vibrio cholerae is the etiological agent of cholera. Its natural reservoir is the aquatic environment. To date, practical typing of V. cholerae is mainly serological and requires about 200 antisera. Simple sequence repeats (SSR), also termed VNTR (for variable number of tandem repeats), provide a source of high genomic polymorphism used in bacterial typing. Here we describe an SSR-based typing method that combines the variation in highly mutable SSR loci, with that of shorter, relatively more stable mononucleotide repeat (MNR) loci, for accurate and rapid typing of V. cholerae. In silico screening of the V. cholerae genome revealed thousands of perfect SSR tracts with an average frequency of one SSR every 152 bp. A panel of 32 V. cholerae strains, representing both clinical and environmental isolates, was tested for polymorphism in SSR loci. Two strategies were applied to identify SSR variation: polymorphism of SSR tracts longer than 12 bp (L-SSR) assessed by capillary fragment-size analysis and MNR polymorphism assessed by sequencing. The nine L-SSR loci tested were all polymorphic, displaying 2 to 13 alleles per locus. Sequence analysis of eight MNR-containing loci (MNR-multilocus sequence typing [MLST]) provided information on both variations in the MNR tract itself, and single nucleotide polymorphism (SNP) in their flanking sequences. Phylogenetic analysis of the combined SSR data showed a clear discrimination between the clinical strains belonging to O1 and O139 serogroups, and the environmental isolates. Furthermore, discrimination between 27 strains of the 32 strains was achieved. SSR-based typing methods combining L-SSR and MNR-MLST were found to be efficient for V. cholerae typing.

Two unrelated cases of septicaemia due to Vibrio cholerae non-O1, non-O139 in Poland, July and August 2006

Two cases of septicaemia caused by Vibrio cholerae non-O1, non-O139 were reported in different regions of Poland during one

Prevalence of virulence genes (ctxA, stn, OmpW and tcpA) among non-O1 Vibrio cholerae isolated from fresh water environment

The virulence of a pathogen is reliant on the presence of a discrete set of genetic determinants and their expression in the host. The virulence of Vibrio spp. is regulated by the ctxAB and tcpA genes. These genes are alleged to be exclusively associated with clinical strains of O1 and O139 serogroups. In the present study, we examined the presence of virulence genes viz. stn, OmpW, ctxA and tcpA of classical and ElTor variants, in environmental strains of non-O1 Vibrio cholerae cultured seasonally from four sampling stations of the river Narmada at Jabalpur (MP), India. Unexpectedly, the PCR analysis of the strains revealed the presence of these genes among environmental V. cholerae. The strains harboring the tcpA gene also carried the ctxA gene. Sequencing of the tcpA gene and ctxA gene carried by an environmental strain showed approximately 97% homology with the previously sequenced genes submitted in the GenBank. We report here the prevalence of cholera toxin gene and the gene for toxin co-regulated pilus among non-O1 V. cholerae strains isolated from fresh water environment. This study supports the idea that cholera toxin has an environmental derivation and that the intricate aquatic environment can give rise to pathogenic Vibrio organisms.

Gene cloning and characterization of four MATE family multidrug efflux pumps from Vibrio cholerae non-O1

There are six putative genes for multidrug and toxic compound extrusion (MATE) family multidrug efflux pumps in the chromosome of Vibrio cholerae. We have so far analyzed two MATE family pumps in V. cholerae non-O1 NCTC4716. Here we cloned four remaining genes for putative MATE family efflux pumps by the PCR method from this microorganism and designated them as vcmB, vcmD, vcmH and vcmN. Each one of the four genes was introduced and expressed in the drug hypersusceptible host Escherichia coli KAM32 cells. We observed elevated MICs of multiple antimicrobial agents, such as fluoroquinolones, aminoglycosides, ethidium bromide and Hoechst 33342 in the transformants. Energydependent efflux of substrate was observed with the transformed cells. We found that efflux activities of VcmB, VcmD and VcmH were Na+-dependent, but that of VcmN was Na+-independent. Thus, all six of the MATE family multidrug efflux pumps of V. cholerae non-O1 have been characterized. We also found that all six genes were expressed in cells of V. cholerae non-O1.

Distribution of virulence markers in clinical and environmental Vibrio cholerae non-O1/non-O139 strains isolated in Brazil from 1991 to 2000

One hundred seventy nine Vibrio cholerae non-O1/non-O139 strains from clinical and different environmental sources isolated in Brazil from 1991 to 2000 were serogrouped and screened for the presence of four different virulence factors. The Random Amplification of Polymorphic DNA (RAPD) technique was used to evaluate the genetic relatedness among strains. Fifty-four different serogroups were identified and V. cholerae O26 was the most common (7.8%). PCR analysis for three genes (ctxA, zot, ace) located of the CTX genetic element and one gene (tcpA) located on the VPI pathogenicity island showed that 27 strains harbored one or more of these genes. Eight (4.5%) strains possessed the complete set of CTX element genes and all but one of these belonged to the O26 serogroup suggesting that V. cholerae O26 has the potential to be an epidemic strain. The RAPD profiles revealed a wide variability among strains and no genetic correlation was observed.

Toxin(s), other than cholera toxin, produced by environmental non O1 non O139 Vibrio cholerae

A total of 39 Vibrio cholerae non O1 non O139 strains were isolated from surface waters of different parts of Dhaka City, Bangladesh. All these strains showed lack of ctx or zot gene, as demonstrated by the PCR analysis. Eighteen representative strains were tested for enterotoxin production using a rabbit ileal loop model, of which live cells of 8 strains and culture filtrates of 6 strains produced fluid accumulation in ileal loops. However, none of them produced heat stable toxin (ST), as detected by suckling mouse assay. On the other hand, 15% of isolates produced cytotoxin as detected by the Chinese Hamster Ovary (CHO) cell assay. Fifty times concentrated culture filtrates of the representative strains did not give any precipitin band against the anti-cholera toxin, suggesting the strains produced an enterotoxin, which is antigenically different from known cholera toxin (CT). Eighty percent of the total isolates were found to be positive for heat labile haemolysin detected by tube method, whereas, 39% were found positive by the Christie-Atkins-Munch-Petersen (CAMP) method. However, 87% of the isolates were positive for haemagglutinin/protease and all of the strains were positive for mannose-sensitive-haemagglutinin assay.

Genetic characterization of Vibrio cholerae isolates from Argentina by V. cholerae repeated sequences-polymerase chain reaction

We have developed a novel typing method based on Vibrio cholerae repeat sequences (VCR) using primers directed out of the VCR sequences. To evaluate the VCR-polymerase chain reaction (PCR) as a typing system, 2 categories, efficacy and efficiency, were analyzed in 69 strains of human and environmental V. cholerae O1 toxigenic and nontoxigenic, and non-O1 strains isolated since 1992-2000 from Argentina. The discriminatory power (0.91), stability (0.95), reproducibility (1), typeability (1), rapidity, accessibility, as well ease of use, indicated that the VCR-PCR method provides an alternative useful tool for molecular epidemiology of V. cholerae. The VCR-PCR of V. cholerae isolates showed 29 patterns, of which pattern 1 represented 68% of the V. cholerae O1 isolates, supporting the hypothesis that a clone with epidemic behavior was responsible for the epidemic in Latin America. These results showed a good correlation and a better epidemiologic analysis when the results were compared in parallel with repetitive extragenic palindromic sequences-PCR. In conclusion, VCR-PCR showed excellent performance as a typing method for cholera surveillance programs.

[Characterization of enteropathogenic Vibrio cholerae non O1/O139 isolated in Uzbekistan]

The results of the serotyping of 244 V. cholerae non O1/O139 cultures isolated from patients in Uzbekistan in 2000 and 2001 are presented. All isolates were studied by the method of molecular probing and in the polymerase chain reaction for the presence of virulence genes and for sensitivity to phages ctx+, ctx- and hemolytic activity. The use of monoreceptor O-sera O2-O83 made it possible to determine vibrios of 32 serogroups with the dominating role in the etiology of acute enteric diseases belonging to serogroups O18, O62, O82, O37. Genes ctx AB were detected in none of the isolates, 5 of them contained gene tcp A. A group of cultures, sensitive to phage ctx+ and belonging mainly to enteropathogenic serogroups, was detected.

Virulence factors of non-O1 non-O139 Vibrio cholerae isolated in Córdoba, Argentina

V. cholerae non-O1 non-O139 serogroups isolated from clinical and environmental sources in Córdoba, Argentina, were analyzed for the presence and expression of virulence genes. Most of the strains studied contained the genes toxR and hlyA, but lacked ctxA, zot, ace, tcpA and stn. The culture supernatants were tested for hemolytic and cytotoxic activity. The enterotoxic potential of the strains was studied in a rabbit ileal loop assay and their genetic profiles were compared by PFGE. The environmental strains varied in their virulence phenotype and showed no clonal relationships. The clinical strains were highly enterotoxic, hemolytic, proteolytic and showed indistinguishable PFGE profiles, although they differed in their cytotoxic activity. This is the first description, using cell culture and "in vivo" studies, of the virulence properties of non-O1 non-O139 V. cholerae from Argentina.

[Study on biology and epidemiological characteristics of vibrio cholerae non-O1 strains isolated from environmental waters in Foshan city]

OBJECTIVE

To study the distribution of serotype and the positive rate of toxins among vibrio cholerae non-O(1) isolated from environmental waters in Foshan city.

METHODS

Water specimens were collected from river and cultured for vibrio cholerae non-O(1). The PCR method was used to detect cholerae enterotoxin (CT) gene; the ELISA method was used to detect heat-stable toxin (ST) and heat-labile toxin (LT).

RESULTS

478 vibrio cholerae non-O(1) strains were isolated from 1 644 water specimens, with a positive rate of 29.07%. Serological assay showed that the main serotype of vibrio cholerae non-O(1) in Foshan city is VBO(7). Positive rate of CT, ST and LT were 1.91%, 13.14% and 12.17%, respectively.

CONCLUSIONS

A few non-O(1) strains were found to have several virulent factors simultaneously, and the results suggest that vibrio cholerae non-O(1) in environmental waters is potentially pathogenic and may affect people's health. It is necessary to pay attention to the prevention of diarrhoea caused by vibrio cholerae.

[The genome polymorphism of Vibrio cholerae ctxAB(-) strains, containing the proximal part of the CTX element]

The comparative analysis of the hybridization patterns of DNA restricts for 20 V. cholerae, groups 01 and non-01 (non-0139), containing the incomplete CTX element (ctxAB-) was carried out with the use of probes, complementary to the genes of the proximal part of the virulence cassettle and flanking its RS1 sequences. This group was found to be heterogeneous both in the number of copies of "truncated" CTX prophage and their localizations in the genome, as well as in the position of the sites of restriction endonucleases HindlII and BglII. Among 17 clinically noncholerigenic isolates, 5 etiologically dangerous clones were found, each of them characterized by the definite time and place of isolation. At least one of them proved to be the causative agent of the local outbreak of diarrheal diseases in Uzbekistan.

Comparative study of different methods for detection of toxic and other enzymatic factors in Vibrio cholerae strains

The purpose of this work was to characterize the toxin profile and the presence of other virulence factors involved in the pathogenesis and biology of 13 V. cholerae O1 (11 clinical cases and 2 waters) and 6 V. cholerae non O1 strains (4 clinical cases and 2 waters) using genetic (PCR), immunological (RPLA), biochemical (NAD degradation, haemolysis, Kanagawa phenomenon, caseinase, lecithinase, mucinase, amylase, esculine hydrolysis) and cell culture (Vero E6, HEp-2) assays. The results indicated a concordance between PCR-RPLA (84%), PCR-NAD (73%) and RPLA-NAD (84%) methods. The sensitivity of RPLA and NAD degradation methods were comparable to PCR in detecting CT in Vibrio cholerae O1 strains. Although NAD degradation method was not exclusively specific for the CT detection, it proved its usefulness in screening certain virulent, CT-negative clones of V. cholerae. The cytotoxic effect on Vero E6 cells, enzyme production (Kanagawa haemolysins, lecithinase, caseinase, esculine hydrolysis) as well as adherence ability on inert substrate proved to be much more constant in V. cholerae non O1 (CT- negative) than in V. cholerae O1 (CT-positive). All V. cholerae non O1 strains isolated in diarrheal cases were Kanagawa positive. This complex of virulence factors detected in V. cholerae non O1 strains could probably contribute during interepidemic periods to human-to-human transmission and to greater resistance as compared to O1 strains in the environment.