Genotypes associated with virulence in environmental isolates of Vibrio cholerae

Wastewater-based surveillance of Vibrio cholerae: Molecular insights on biofilm regulatory diguanylate cyclases, virulence factors and antibiotic resistance patterns

Vibrio cholerae is an inherent inhabitant of aquatic ecosystems. The Indian state of West Bengal, especially the Gangetic delta region is the highest cholera affected region and is considered as the hub of Asiatic cholera. V. cholerae were isolated from publicly accessible wastewater of Midnapore, West Bengal, India. Serotyping determined all isolates to be of non-O1/non-O139 serogroups. Moderate biofilm-forming abilities were noticed in most of the isolates (74.7 %) while, high biofilm formation was recorded for only 6.3 % isolates and 19 % of isolates exhibited low/non-biofilm-forming abilities. PCR-based screening of crucial diguanylate cyclases (DGCs) involved in cyclic-di-GMP-mediated biofilm signaling was performed. cdgH and cdgM were the most abundant DGCs among 93.7 % and 91.5 % of isolates, respectively. Other important DGCs, i.e., cdgK, cdgA, cdgL, and vpvC were present in 84 %, 75.5 %, 72 % and 68 % of isolates, respectively. Besides, the non-O1/non-O139 isolates were screened for the occurrence of virulence factor encoding genes. Moreover, among these non-O1/non-O139 isolates, two strains (3.17 %) harbored both ctxA and ctxB genes, which encode the cholera toxin associated with epidemic cholera. ompU was the most prevalent virulence factor, present in 24.8 % of isolates. Other virulence factors like, zot and st were found in 4.7 % and 9.5 % of isolates. Genes encoding tcp and ace were found to be PCR-negative for the isolates. Additionally, crucial virulence factor regulators, toxT, toxR and hapR were found to be PCR-positive in all the isolates. Antibiotic resistance patterns displayed further vulnerabilities with decreased sensitivity towards commonly used antibiotics with multiple antibiotic resistance index ranging between 0.37 and 0.62. The presence of cholera toxin-encoding multi-drug resistant (MDR) V. cholerae strains in environmental settings is alarming. High occurrence of DGCs are considered to encourage further investigations to use them as alternative therapeutic targets against MDR cholera pathogen due to their unique presence in bacterial systems.

One-year monitoring of potentially pathogenic microorganisms in the waters and sediments of the Lesina and Varano lagoons (South-East Italy)

In this study, two Mediterranean coastal lagoons (Lesina and Varano) of southern Italy, located in the north of the Apulia region, were investigated for the presence of Shiga toxin Escherichia coli (STEC) and potentially enteropathogenic Vibrio species in parallel with norovirus (NoV), hepatitis A virus (HAV), hepatitis E virus (HEV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aimed to evaluate the presence of potentially pathogenic bacteria and viruses in the water and sediments of these ecosystems. From March 2022 to February 2023, a total of 98 samples were collected: 49 water samples and 49 sediment samples. STEC strains were isolated in three samples (3.1%), of which one (2%) was water (stx1 and stx2 positive) and two (4.1%) were sediment (both stx2 positive) samples. Vibrio spp. were detected in twenty samples (20.4%), of which nine were water (18.4%) and eleven were sediment (22.4%) samples. The species detected included V. parahaemolyticus, V. cholerae, and V. vulnificus. NoV was detected in 25 (25.5%) samples, while none of the water or sediment samples were positive for HAV, HEV, and SARS-CoV-2. The results of this study provide an overview of the presence of potentially pathogenic microorganisms in areas influenced by anthropogenic pressure. Monitoring the circulation of these pathogens could be useful to evaluate the water flowing into the lagoons, in particular discharge waters (i.e., urban, agricultural, and livestock runoff), considering the presence of fish and shellfish farms in these sites.

Emergence of multidrug resistant, ctx negative seventh pandemic Vibrio cholerae O1 El Tor sequence type (ST) 69 in coastal water of Kerala, India

Seventh pandemic Vibrio choleare O1 El Tor strain is responsible for the on-going pandemic outbreak of cholera globally. This strain evolved from non-pathogenic V. cholerae by acquiring seventh pandemic gene (VC 2346), pandemic Islands (VSP1 and VSP2), pathogenicity islands (VP1 and VP2) and CTX prophage region. The cholera toxin production is mainly attributed to the presence of ctx gene in these strains. However, several variants of this strain emerged as hybrid strains or atypical strains. The present study aimed to assess the aquatic environment of Cochin, India, over a period of 5 years for the emergence of multidrug resistant V. cholerae and its similarity with seventh pandemic strain. The continuous surveillance and monitoring resulted in the isolation of ctx negative, O1 positive V. cholerae isolate (VC6) from coastal water, Cochin, Kerala. The isolate possessed the biotype specific O1 El Tor tcpA gene and lacked other biotype specific ctx, zot, ace and rst genes. Whole genome analysis revealed the isolate belongs to pandemic sequence type (ST) 69 with the possession of pandemic VC2346 gene, pathogenic island VPI1, VPI2, and pandemic island VSP1 and VSP2. The isolate possessed several insertion sequences and the SXT/R391 family related Integrative Conjugative Elements (ICEs). In addition to this, the isolate genome carried virulence genes such as VgrG, mshA, ompT, toxR, ompU, rtxA, als, VasX, makA, and hlyA and antimicrobial resistance genes such as gyrA, dfrA1, strB, parE, sul2, parC, strA, VC1786ICE9-floR, and catB9. Moreover, the phylogenetic analysis suggests that the isolate genome is more closely related to seventh pandemic V. cholerae O1 N16961 strain. This study reports the first incidence of environmental ctx negative seventh pandemic V. choleare O1 El Tor isolate, globally and its presence in the aquatic system likely to induce toxicity in terms of public health point of view. The presence of this isolate in the aquatic environment warns the strict implementation of the epidemiological surveillance on the occurrence of emerging strains and the execution of flagship program for the judicious use of antibiotics in the aquatic ecosystem.

Toxigenic Vibrio cholerae strains in South-East Queensland, Australian river waterways

Cholera is a major public health problem in developing and underdeveloped countries; however, it remains of concern to developed countries such as Australia as international travel-related or locally acquired cholera or diarrheal disease cases are still reported. Cholera is mainly caused by cholera toxin (CT) producing toxigenic O1 and O139 serogroup Vibrio cholerae strains. While most toxigenic V. cholerae cases in Australia are thought to be caused by international-acquired infections, Australia has its own indigenous toxigenic and non-toxigenic O1 and non-O1, non-O139 V. cholerae (NOVC) strains. In Australia, in the 1970s and again in 2012, it was reported that south-east Queensland riverways were a reservoir for toxigenic V. cholerae strains that were linked to local cases. Further surveillance on environmental reservoirs, such as riverways, has not been reported in the literature in the last 10 years. Here we present data from sites previously related to outbreaks and surveillance sampling to detect the presence of V. cholerae using PCR in conjunction with MALDI-TOF and whole-genome sequencing. In this study, we were able to detect NOVC at all 10 sites with all sites having toxigenic non-O1, non-O139 strains. Among 133 NOVC isolates, 22 were whole-genome sequenced and compared with previously sequenced Australian O1 and NOVC strains. None of the samples tested grew toxigenic or non-toxigenic O1 or O139, responsible for epidemic disease. Since NOVC can be pathogenic, continuous surveillance is required to assist in theclinical and envir rapid identification of sources of any outbreaks and to assist public health authorities in implementing control measures. IMPORTANCE Vibrio cholerae is a natural inhabitant of aquatic environments, both freshwater and seawater, in addition to its clinical significance as a causative agent of acute diarrhea and extraintestinal infections. Previously, both toxigenic and non-toxigenic, clinical, and environmental V. cholerae strains have been reported in Queensland, Australia. This study aimed to characterize recent surveillance of environmental NOVC strains isolated from Queensland River waterways to understand their virulence, antimicrobial resistance profile and to place genetic current V. cholerae strains from Australia in context with international strains. The findings from this study suggest the presence of unique toxigenic V. cholerae in Queensland river water systems that are of public health concern. Therefore, ongoing monitoring and genomic characterization of V. cholerae strains from the Queensland environment is important and would assist public health departments to track the source of cholera infection early and implement prevention strategies for future outbreaks. The genomics of environmental V. cholerae could assist us to understand the natural ecology and evolution of this bacterium in natural environments with respect to global warming and climate change.

Incidence and Virulence Factor Profiling of Vibrio Species: A Study on Hospital and Community Wastewater Effluents

This study aimed to determine the incidence and virulence factor profiling of Vibrio species from hospital wastewater (HWW) and community wastewater effluents. Wastewater samples from selected sites were collected, processed, and analysed presumptively by the culture dependent methods and molecular techniques. A total of 270 isolates were confirmed as Vibrio genus delineating into V. cholerae (27%), V. parahaemolyticus (9.1%), V. vulnificus (4.1%), and V. fluvialis (3%). The remainder (>50%) may account for other Vibrio species not identified in the study. The four Vibrio species were isolated from secondary hospital wastewater effluent (SHWE), while V. cholerae was the sole specie isolated from Limbede community wastewater effluent (LCWE) and none of the four Vibrio species was recovered from tertiary hospital wastewater effluent (THWE). However, several virulence genes were identified among V. cholerae isolates from SHWE: ToxR (88%), hylA (81%), tcpA (64%), VPI (58%), ctx (44%), and ompU (34%). Virulence genes factors among V. cholerae isolates from LCWE were: ToxR (78%), ctx (67%), tcpA (44%), and hylA (44%). Two different genes (vfh and hupO) were identified in all confirmed V. fluvialis isolates. Among V. vulnificus, vcgA (50%) and vcgB (67%) were detected. In V. parahaemolyticus, tdh (56%) and tlh (100%) were also identified. This finding reveals that the studied aquatic niches pose serious potential health risk with Vibrio species harbouring virulence signatures. The distribution of virulence genes is valuable for ecological site quality, as well as epidemiological marker in the control and management of diseases caused by Vibrio species. Regular monitoring of HWW and communal wastewater effluent would allow relevant establishments to forecast, detect, and mitigate any public health threats in advance.

Molecular characterization of Vibrio species isolated from dairy and water samples

Vibrio species can cause foodborne infections and lead to serious gastrointestinal illnesses. The purpose of this research was to detect the Vibrio cholerae and Vibrio parahaemolyticus in raw milk, dairy products, and water samples. Also, it investigated the virulence factors, antibiotic resistance and biofilm formation in isolated bacteria. Conventional and molecular approaches were used to identify the isolates in this study. Vibrio species were detected in 5% of the samples. Vibrio cholerae and Vibrio parahaemolyticus were isolated from 1.25 and 1.5%, respectively, of the total samples. Penicillin resistance was detected in all strains of Vibrio cholerae and Vibrio parahaemolyticus, with a MAR index ranging from 0.16 to 0.5. Four isolates were moderate biofilm producer and three of them were MDR. When Vibrio cholerae was screened for virulence genes, ctxAB, hlyA, and tcpA were found in 80, 60, and 80% of isolates, respectively. However, tdh + /trh + associated-virulence genes were found in 33.3% of Vibrio parahaemolyticus isolates.

Evidence of Antibiotic Resistance and Virulence Factors in Environmental Isolates of Vibrio Species

The outbreak of waterborne diseases such as cholera and non-cholera (vibriosis) is continuously increasing in the environment due to fecal and sewage discharge in water sources. Cholera and vibriosis are caused by different species of Vibrio genus which are responsible for acute diarrheal disease and soft tissue damage. Although incidences of cholera and vibriosis have been reported from the Vaishali district of Bihar, India, clinical or environmental strains have not been characterized in this region. Out of fifty environmental water samples, twelve different biochemical test results confirmed the presence of twenty Vibrio isolates. The isolates were found to belong to five different Vibrio species, namely V. proteolyticus, V. campbellii, V. nereis, V. cincinnatiensis, and V. harveyi. From the identified isolates, 65% and 45% isolates were found to be resistant to ampicillin and cephalexin, respectively. Additionally, two isolates were found to be resistant against six and four separately selected antibiotics. Furthermore, virulent hlyA and ompW genes were detected by PCR in two different isolates. Additionally, phage induction was also noticed in two different isolates which carry lysogenic phage in their genome. Overall, the results reported the identification of five different Vibrio species in environmental water samples. The isolates showed multiple antibacterial resistance, phage induction, and virulence gene profile in their genome.

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.

Systematic Survey of Vibrio spp. and Salmonella spp. in Bivalve Shellfish in Apulia Region (Italy): Prevalence and Antimicrobial Resistance

The emergence of antimicrobial resistance (AMR) is increasingly common across the globe and aquatic ecosystems could be considered a reservoir of antibiotic-resistant bacteria. This study aimed to determine prevalence and antibiotic susceptibility of the potential pathogenic bacteria Salmonella spp. and Vibrio spp. in bivalve molluscs intended for human consumption, collected over a period of 19 months along the northern coast of Apulia region. The AMR profile was also determined in non-pathogenic Vibrio species, common natural inhabitants of seawater and a useful indicator for the surveillance of AMR in the environment. The current study presents data on the AMR of 5 Salmonella and 126 Vibrio isolates by broth microdilution MIC. Multidrug resistance (MDR) was observed in one S. Typhimurium strain towards sulfamethoxazole, trimethoprim, tetracycline, gentamicin, and ampicillin and in 41.3% of the Vibrio strains, mostly towards sulphonamides, penicillin, and cephems. All Vibrio isolates were sensitive to azithromycin, chloramphenicol, tetracycline, amoxicillin/clavulanic acid, gentamicin, streptomycin, amikacin, and levofloxacin. The AMR phenomenon in the investigated area is not highly worrying but not entirely negligible; therefore, in-depth continuous monitoring is suggested. Results concerning the antibiotic agents without available specific clinical breakpoints could be useful to upgrade the MIC distribution for Vibrio spp. but, also, the establishment of interpretative criteria for environmental species is necessary to obtain a more complete view of this issue.

Improving environmental monitoring of Vibrionaceae in coastal ecosystems through 16S rRNA gene amplicon sequencing

The Vibrionaceae family groups genetically and metabolically diverse bacteria thriving in all marine environments. Despite often representing a minor fraction of bacterial assemblages, members of this family can exploit a wide variety of nutritional sources, which makes them important players in biogeochemical dynamics. Furthermore, several Vibrionaceae species are well-known pathogens, posing a threat to human and animal health. Here, we applied the phylogenetic placement coupled with a consensus-based approach using 16S rRNA gene amplicon sequencing, aiming to reach a reliable and fine-level Vibrionaceae characterization and identify the dynamics of blooming, ecologically important, and potentially pathogenic species in different sites of the northern Adriatic Sea. Water samples were collected monthly at a Long-Term Ecological Research network site from 2018 to 2021, and in spring and summer of 2019 and 2020 at two sites affected by depurated sewage discharge. The 41 identified Vibrionaceae species represented generally below 1% of the sampled communities; blooms (up to ~ 11%) mainly formed by Vibrio chagasii and Vibrio owensii occurred in summer, linked to increasing temperature and particulate matter concentration. Pathogenic species such as Vibrio anguilllarum, Vibrio tapetis, and Photobacterium damselae were found in low abundance. Depuration plant samples were characterized by a lower abundance and diversity of Vibrionaceae species compared to seawater, highlighting that Vibrionaceae dynamics at sea are unlikely to be related to wastewater inputs. Our work represents a further step to improve the molecular approach based on short reads, toward a shared, updated, and curated phylogeny of the Vibrionaceae family.

Identification and whole-genome sequencing analysis of Vibrio vulnificus strains causing pearl gentian grouper disease in China

Vibrio vulnificus is a pathogenic bacterium that causes disease in marine fish, affecting fish farming and human health worldwide. In May 2021, in the Bohai Bay region, a disease broke out in commercially farmed pearl gentian grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus), causing huge economic losses. The diseased fish had skin lesions, water accumulation in their abdomens, and showed tissue and organ damage. V. vulnificus biotype 2 has been reported in eels and other marine fish, but it is less reported in pearl gentian grouper. In this study, the pathogenic strain isolated from diseased fish was identified as V. vulnificus EPL 0201 biotype 2 on the basis of physiological and biochemical characteristics and the results of 16S rRNA gene and gyrB sequencing, virulence gene detection, and recursive infection experiments. To gain a comprehensive understanding of the pathogenicity and drug resistance of this strain, whole-genome sequencing was performed. Whole-genome analysis showed that the gene map of this strain was complete. The Virulence Factor Database annotation results showed that this strain had the key virulence factor genes vvhA and rtxA, which cause host disease. In addition, this strain had genes conferring resistance against cephalosporins, aminoglycosides, tetracyclines, and sulfonamides. Antimicrobial susceptibility testing confirmed the presence of these resistance genes identified in the genome. The results of this study show that V. vulnificus EPL 0201 biotype 2 is a multi-drug resistant strain with high pathogenicity.

Exploring the dynamics of toxigenic environmental Vibrio mimicus and its comparative analysis with Vibrio cholerae of the southern Gangetic delta

Vibrio mimicus and Vibrio cholerae are closely related species. Environmental V.mimicus were comparatively analyzed with V.cholerae, for the presence of virulence genes, antibiotic susceptibility, resistance genes, in-vitro hemolysis, and biofilm formation. Phylogenetic analysis was performed depending on toxin-gene disposition and isolation area. One V.mimicus isolate harbored ctxA, tcp El-Tor, toxT and toxS, whereas several strains contained incomplete copies of virulence cassettes and associated toxin genes. V.cholerae isolates harbored ctx, tcp and toxT genes, with a higher preponderance of hlyA, rtxA and toxR genes. V.mimicus were highly sensitive to amino/carboxy-penicillins, furazolidone & gentamycin, with quinolone & tetracycline resistance genes. V.cholerae isolates were sensitive to penicillins and cephalosporins, with 29% of the strains bearing the sxt gene. Phylogenetically, the apomorphic strains of both species were unique to the inland sites. V.cholerae has embodied an enormous public health burden globally but our findings emphasize the role of V.mimicus as an emerging etiological agent with similar epidemic potential.

Prevalence and molecular characterization of Vibrio cholerae from fruits and salad vegetables sold in Jakarta, Indonesia, using most probable number and PCR

OBJECTIVE

Cholera is an intestinal infection caused by Vibrio cholerae, it is usually occurs in developing countries that lack of sanitation. In developing country including Indonesia, awareness importance of sanitation is still low. Unfortunately, research related to the detection of V. cholerae from fruit and vegetables in Indonesia is still rare. In this study, MPN method was used to determine the prevalence of V. cholerae followed by single and multiplex PCR to detect virulence genes, including toxR, ctxA, tcpA, hlyA, ace, ompU, and zot.

RESULTS

We found 3 fruits and 2 vegetables positive for toxR gene. Fruit samples which were showed toxR positive found from East Jakarta while for vegetables, it was recovered from West Jakarta and Central Jakarta. Twenty-three isolates were recovered from toxR positive samples. The result of antibiotic resistance analysis showed that 4.35% of the isolates resistant to gentamicin, streptomycin (17.39%), trimethoprim (52.17%), ciprofloxacin (30.43%), ampicillin (13.04%), nalidixic acid (82.61%), and polymyxin B (91.30%). None of these isolates were resistant to kanamycin. Combination of MPN and Multiplex PCR method can be used to detect the prevalence and characterize the virulence properties of V. cholerae.

Detection of mcr-1 Gene in Undefined Vibrio Species Isolated from Clams

The increase of antimicrobial resistant strains is leading to an emerging threat to public health. Pathogenic Vibrio are responsible for human and animal illness. The Enterobacteriaceae family includes microorganisms that affect humans, causing several infections. One of the main causes of human infection is related to the ingestion of undercooked seafood. Due to their filter-feeding habit, marine invertebrates, such as clams, are known to be a natural reservoir of specific microbial communities. In the present study, Vibrionaceae and coliforms microorganisms were isolated from clams. A microbial susceptibility test was performed using the disk diffusion method. From 43 presumptive Vibrio spp. and 17 coliforms, three Vibrio spp. with MICs to colistin >512 mg L-1 were found. From the 23 antimicrobial resistance genes investigated, only the three isolates that showed phenotypic resistance to colistin contained the mcr-1 gene. Genotypic analysis for virulence genes in EB07V indicated chiA gene presence. The results from the plasmid cure and transformation showed that the resistance is chromosomally mediated. Biochemical analysis and MLSA, on the basis of four protein-coding gene sequences (recA, rpoB, groEL and dnaJ), grouped the isolates into the genus Vibrio but distinguished them as different from any known Vibrio spp.

Atypical and dual biotypes variant of virulent SA-NAG-Vibrio cholerae: an evidence of emerging/evolving patho-significant strain in municipal domestic water sources

Introduction and purpose

The recent cholera spread, new cases, and fatality continue to arouse concern in public health systems; however, interventions on control is at its peak yet statistics show continuous report. This study characterized atypical and patho-significant environmental Vibrio cholerae retrieved from ground/surface/domestic water in rural-urban-sub-urban locations of Amathole District municipality and Chris Hani District municipality, Eastern Cape Province, South Africa.

Methods

Domestic/surface water was sampled and 759 presumptive V. cholerae isolates were retrieved using standard microbiological methods. Virulence phenotypic test: toxin co-regulated pili (tcp), choleragen red, protease production, lecithinase production, and lipase test were conducted. Serotyping using polyvalent antisera (Bengal and Ogawa/Inaba/Hikojima) and molecular typing: 16SrRNA, OmpW, serogroup (Vc-O1/O139), biotype (tcpAClas/El Tor, HlyAClas/El Tor, rstRClas/El Tor, RS1, rtxA, rtxC), and virulence (ctxA, ctxB, zot, ace, cep, prt, toxR, hlyA) genes were targeted.

Result

Result of 16SrRNA typing confirmed 508 (66.9%) while OmpW detected/confirmed 61 (12.01%) V. cholerae strains. Phenotypic-biotyping scheme showed positive test to polymyxin B (68.9%), Voges proskauer (6.6%), and Bengal serology (11.5%). Whereas Vc-O1/O139 was negative, yet two of the isolates harbored the cholera toxin with a gene-type ctxB and hlyAClas: 2/61, revealing atypical/unusual/dual biotype phenotypic/genotypic features. Other potential atypical genotypes detected include rstR: 7/61, Cep: 15/61, ace: 20/61, hlyAElTor: 53/61, rtxA: 30/61, rtxC: 11/61, and prtV: 15/61 respectively.

Conclusion

Although additional patho-significant/virulent genotypes associated with epidemic/sporadic cholera cases were detected, an advanced, bioinformatics, and post-molecular evaluation is necessary. Such stride possesses potential to adequately minimize future cholera cases associated with dynamic/atypical environmental V. cholerae strains.

Epidemiologic potentials and correlational analysis of Vibrio species and virulence toxins from water sources in greater Bushenyi districts, Uganda

Adequate water supply is one of the public health issues among the population living in low-income settings. Vibriosis remain a significant health challenge drawing the attention of both healthcare planners and researchers in South West districts of Uganda. Intending to clamp down the disease cases in the safest water deprive locality, we investigated the virulent toxins as contaminants and epidemiologic potentials of Vibrio species recovered from surface waters in greater Bushenyi districts, Uganda. Surface water sources within 46 villages located in the study districts were obtained between June and October 2018. Standard microbiological and molecular methods were used to analyse samples. Our results showed that 981 presumptive isolates retrieved cell counts of 10-100 CFU/g, with, with (640) 65% confirmed as Vibrio genus using polymerase chain reaction, which is distributed as follows; V. vulnificus 46/640 (7.2%), V. fluvialis 30/594 (5.1), V. parahaemolyticus 21/564 (3.7), V. cholera 5/543 (0.9), V. alginolyticus 62/538 (11.5) and V. mimicus 20/476 (4.2). The virulence toxins observed were heat-stable enterotoxin (stn) 46 (82.10%), V. vulnificus virulence gene (vcgCPI) 40 (87.00%), extracellular haemolysin gene {vfh 21 (70.00)} and Heme utilization protein gene {hupO 5 (16.70)}. The cluster analysis depicts hupO (4.46% n = 112); vfh (18.75%, n = 112); vcgCPI and stn (35.71%, & 41.07%, n = 112). The principal component analysis revealed the toxins (hupO, vfh) were correlated with the isolate recovered from Bohole water (BW) source, while (vcgCPI, stn) toxins are correlated with natural raw water (NRW) and open springs (OS) water sources isolates. Such observation indicates that surface waters sources are highly contaminated with an odds ratio of 1.00, 95% CI (70.48-90.5), attributed risk of (aR = 64.29) and relative risk of (RR = 73.91). In addition, it also implies that the surface waters sources have > 1 risk of contamination with vfh and > six times of contamination with hupO (aR = 40, - 66). This is a call of utmost importance to the population, which depends on these water sources to undertake appropriate sanitation, personal hygienic practices and potential measures that ensure water quality.

Molecular characterization of Vibrio cholerae O1 El Tor strains in Malaysia revealed genetically diverse variant lineages

Vibrio cholerae O1 El Tor variants have been the major causative agents of cholera worldwide since their emergence in the 2000s. Cholera remains endemic in some regions in Malaysia. Therefore, we aimed to investigate the genetic characteristics of the V. cholerae O1 El Tor strains associated with outbreaks and sporadic cases to elucidate the molecular evolution among the strains circulating in this region. A total of 45 V. cholerae O1 El Tor strains isolated between 1991 and 2011 were examined. All strains were subjected to phenotypic characterization, and molecular characterization including detection of virulence genes and CTX prophage (CTXΦ) by Polymerase Chain Reaction (PCR) and genotyping by Pulsed-Field Gel Electrophoresis (PFGE). All strains were phenotypically confirmed as El Tor biotype and were mostly Ogawa serotype (96%). Antimicrobial susceptibility testing showed that the outbreak strains isolated in 1991 (Sabah) and 2009 (Terengganu) were all multidrug-resistant while the sporadic strains were resistant to erythromycin and furazolidone only. All strains (n = 45) were resistant to erythromycin. The virulence genes ctxA, ctxB, ompW, rfb, rtxC, tcpA, tcpI, rstR, zot and hlyA were present in all strains. The outbreak strains isolated in 1991 harboured El Tor cholera toxin gene (ctxB3) while sporadic strains from 2004 to 2011 harboured classical ctxB1. Four distinctive CTXΦ arrays were identified among the El Tor variants, one of which co-occurred with El Tor strains during the 2009 outbreak in Terengganu. PFGE analysis revealed that a genetically diverse El Tor variants population persisted in Sabah. The co-existence of multiple El Tor variants together with the prototypic El Tor strains suggested a multiclonal emergence of V. cholerae O1 El Tor variants in this region.

Characterization of V. cholerae O1 biotype El Tor serotype Ogawa possessing the ctxB gene of the classical biotype isolated from well water associated with the cholera outbreak in Kerala, South India

We investigated 22 water samples (17 well water and five pipe water - both chlorinated) and six soil samples from the surroundings of wells of the households of suspected patients from Palakkad district, Kerala (India), from where a cholera outbreak was reported during June-July 2016. A total of 25 Vibrio cholerae isolates were collected from three well water samples during a recent cholera outbreak. Biochemical and serological studies revealed that all of the isolates belonged to serogroup O1, biotype El Tor, serotype Ogawa. PCR assays confirmed the occurrence of ctxB, ctxA, hlyA, tcpA El Tor,VPI, ace, zot, ompW, rfbO1 and toxR genes in all isolates. The presence of the ctxB gene of the classical biotype in all of the El Tor isolates suggests that it is a new variant of El Tor biotype. Antibiogram profile of all V. cholerae O1 isolates revealed resistance towards five classes of antibiotics island and indicates that they were multidrug resistant. ERIC-PCR and PFGE finger prints showed the clonal relationship among the V. cholerae O1 isolates. The results of this study revealed the emergence of a new variant of El Tor biotype in the water samples from Palakkad district, from where a cholera outbreak was reported.

First Experimental Evidence for the Presence of Potentially Toxic Vibrio cholerae in Snails, and Virulence, Cross-Resistance and Genetic Diversity of the Bacterium in 36 Species of Aquatic Food Animals

Vibrio cholerae is the most common waterborne pathogen that can cause pandemic cholera in humans. Continuous monitoring of V. cholerae contamination in aquatic products is crucial for assuring food safety. In this study, we determined the virulence, cross-resistance between antibiotics and heavy metals, and genetic diversity of V. cholerae isolates from 36 species of aquatic food animals, nearly two-thirds of which have not been previously detected. None of the V. cholerae isolates (n = 203) harbored the cholera toxin genes ctxAB (0.0%). However, isolates carrying virulence genes tcpA (0.98%), ace (0.5%), and zot (0.5%) were discovered, which originated from the snail Cipangopaludina chinensis. High occurrences were observed for virulence-associated genes, including hapA (73.4%), rtxCABD (68.0–41.9%), tlh (54.2%), and hlyA (37.9%). Resistance to moxfloxacin (74.9%) was most predominant resistance among the isolates, followed by ampicillin (59.1%) and rifampicin (32.5%). Approximately 58.6% of the isolates displayed multidrug resistant phenotypes. Meanwhile, high percentages of the isolates tolerated the heavy metals Hg²⁺ (67.0%), Pb²⁺ (57.6%), and Zn²⁺ (57.6%). Distinct virulence and cross-resistance profiles were discovered among the V. cholerae isolates in 13 species of aquatic food animals. The ERIC-PCR-based genome fingerprinting of the 203 V. cholerae isolates revealed 170 ERIC-genotypes, which demonstrated considerable genomic variation among the isolates. Overall, the results of this study provide useful data to fill gaps for policy and research related to the risk assessment of V. cholerae contamination in aquatic products.

First case of non-O1/O139 Vibrio cholerae infection in the pink-tailed chalceus Chalceus macrolepidotus in China

A pathogen was isolated from diseased pink-tailed chalceus Chalceus macrolepidotus during a high-mortality outbreak in a freshwater culture farm in Liaoyang, China. The diseased fish were characterized by disoriented behaviors, exophthalmos, and redness and swelling of the top of the head. A Gram-negative, pure strain of bacteria (CM0428) was isolated from the brain, kidney, and liver. The isolate was identified as Vibrio cholerae based on ompW gene amplification and 16S rRNA and gyrB gene sequence analysis. Serogroup testing indicated that CM0428 was a non-O1/O139 strain of V. cholerae. The challenge test showed that CM0428 exhibited strong virulence to pink-tailed chalceus, and hlyA and toxR virulence-related genes were detected. The isolate was sensitive to multi-class antibiotics, but resistant to tetracycline. Histological examination revealed that V. cholerae CM0428 infection caused multiple organ and tissue lesions, and typical pathological features were cell degeneration and necrosis.

Probiotics inspired from natural ecosystem to inhibit the growth of Vibrio spp. causing white gut syndrome in Litopenaeus vannamei

Probiotics inspired by host-microbe interactions in the natural ecosystem are propitious in controlling bacterial infections in aquaculture and veterinary systems. Here we report the isolation and characterization of pathogenic Vibrio spp. and lactic acid bacteria from an intensive culture system of Litopenaeus vannamei and natural ecosystem, respectively. The pathogen isolated from the gut of L. vannamei showing the symptoms of white gut disease were identified as V. parahaemolyticus and V. campbelli. Both the pathogens expressed the virulence genes, rtxA, and tcpA and were showing multiple antibiotic resistance (MAR) index of more than 0.5. The lactic acid bacteria isolated from the sediment and gut of benthic organisms (shrimp and polychaetes) collected from a tropical estuary were classified as member of 9 OTUs such as Pediococcus stilessi, Lactobacillus fermentum, L. rhamnosus, Weissella cibaria, Enterococcus durans, E. fecalis, Streptococcus gallolyticus and L. garvieae. Majority of these isolates were facultative in nature and were able to tolerate gastric juice and bile salt. Out of 83 bacteria isolated from sediment and gut, 36 showed abilities to reduce the pH of culture medium to less than five. Many of these isolates (34 Nos.) showed production of hydrolytic enzymes and secondary metabolites with antagonistic activity against both the pathogens (1 No.) or separately toward V. parahaemolyticus (9 Nos.) and V. campbelli (11 Nos.). Overall, the current study proposes a natural ecosystem as a potential source of lactic acid bacteria with probiotic potentials to prevent the vibriosis disease outbreaks in shrimp aquaculture systems. Further studies are required to understand the abilities of lactic acid bacteria to colonize shrimp intestine, stimulate immune system and manipulate microbiome.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-020-02618-2.

Virulence, Resistance, and Genomic Fingerprint Traits of Vibrio cholerae Isolated from 12 Species of Aquatic Products in Shanghai, China

Vibrio cholerae is a waterborne bacterium and can cause epidemic cholera disease worldwide. Continuous monitoring of V. cholerae contamination in aquatic products is imperative for assuring food safety. In this study, we determined virulence, antimicrobial susceptibility, heavy metal tolerance, and genomic fingerprints of 370 V. cholerae isolates recovered from 12 species of commonly consumed aquatic products collected from July to September of 2018 in Shanghai, China. Among the species, Leiocassis longirostris, Ictalurus punetaus, Ophiocephalus argus Cantor, and Pelteobagrus fulvidraco were for the first time detected for V. cholerae. Toxin genes ctxAB, tcpA, ace, and zot were absent from all the V. cholerae isolates. However, high occurrence of virulence-associated genes was detected, such as hapA (82.7%), hlyA (81.4%), rtxCABD (81.4%, 24.3%, 80.3%, and 80.8%, respectively), and tlh (80.5%). Approximately 62.2% of the 370 V. cholerae isolates exhibited resistance to streptomycin, followed by ampicillin (60.3%), rifampicin (53.8%), trimethoprim (38.4%), and sulfamethoxazole-trimethoprim (37.0%). Moreover, ∼57.6% of the isolates showed multidrug resistant phenotypes with 57 resistance profiles, which was significantly different among the 12 species (multiple antimicrobial resistance index, p < 0.001). Meanwhile, high incidence of tolerance to heavy metals Hg²⁺ (69.5%), Ni²⁺ (32.4%), and Cd²⁺ (30.8%) was observed among the isolates. The enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR)-based fingerprinting profiles classified the 370 V. cholerae isolates into 239 different ERIC-genotypes, which demonstrated diverse genomic variation among the isolates. Overall, the results in this study meet the increasing need of food safety risk assessment of aquatic products.

Interbacterial competition and anti-predatory behaviour of environmental Vibrio cholerae strains

Vibrio cholerae isolates responsible for cholera pandemics represent only a small portion of the diverse strains belonging to this species. Indeed, most V. cholerae are encountered in aquatic environments. To better understand the emergence of pandemic lineages, it is crucial to discern what differentiates pandemic strains from their environmental relatives. Here, we studied the interaction of environmental V. cholerae with eukaryotic predators or competing bacteria and tested the contributions of the haemolysin and the type VI secretion system (T6SS) to those interactions. Both of these molecular weapons are constitutively active in environmental isolates but subject to tight regulation in the pandemic clade. We showed that several environmental isolates resist amoebal grazing and that this anti‐grazing defense relies on the strains' T6SS and its actincross‐linking domain (ACD)‐containing tip protein. Strains lacking the ACD were unable to defend themselves against grazing amoebae but maintained high levels of T6SS‐dependent interbacterial killing. We explored the latter phenotype through whole‐genome sequencing of 14 isolates, which unveiled a wide array of novel T6SS effector and (orphan) immunity proteins. By combining these in silico predictions with experimental validations, we showed that highly similar but non‐identical immunity proteins were insufficient to provide cross‐immunity among those wild strains.

The Impact of Water Intrusion on Pathogenic Vibrio Species to Inland Brackish Waters of China

The estuary is the ecological niche of pathogenic Vibrio spp. as it provides abundant organic and inorganic nutrients from seawater and rivers. However, little is known about the ecology of these Vibrio species in the inland brackish water area. In this study, their co-occurrence and relationships to key environmental constraints (salinity and temperature) in the Hun-Tai River of China were examined using the most probable number polymerase chain reaction (MPN-PCR) approach. We hereby report 2-year continuous surveillance based on six water indices of the Hun-Tai River. The results showed that seawater intrusion maximally reached inland as far as 26.5 km for the Hun-Tai River. Pathogenic Vibrio spp. were detected in 21.9% of the water samples. In particular, V. cholerae, V. parahaemolyticus, and V. vulnificus were isolated in 10 (10.4%), 20 (20.8.5%), and 2 (2.08%) samples, respectively. All V. parahaemolyticus strains were tdh gene negative, 10% were positive for the trh gene. Multi-locus sequence typing (MLST) divided V. parahaemolyticus strains into 12 sequence types (STs) for the Hun-Tai River. Five STs were respectively present in various locations along the Hun-Tai River. The PCR assay for detecting six virulence genes and Vibrio seventh pandemic island I and II revealed three genotypes in 12 V. cholerae isolates. The results of our study showed that seawater intrusion and salinity have profound effects on the distribution of pathogenic Vibrio spp. in the inland river, suggesting a potential health risk associated with the waters of the Hun-Tai River used for irrigation and drinking.

Characterization of Vibrio cholerae isolates from freshwater sources in northwest Ohio

Vibrio cholerae is a natural inhabitant of aquatic ecosystems worldwide, typically residing in coastal or brackish water. While more than 200 serogroups have been identified, only serogroups O1 and O139 have been associated with epidemic cholera. However, infections other than cholera can be caused by nonepidemic, non-O1/non-O139 V. cholerae strains, including gastroenteritis and extraintestinal infections. While V. cholerae can also survive in freshwater, that is typically only observed in regions of the world where cholera is endemic. We recently isolated V. cholerae from several locations in lakes and rivers in northwest Ohio. These isolates were all found to be non-O1/non-O139 V. cholerae strains, that would not cause cholera. However, these isolates contained a variety of virulence genes, including ctxA, rtxA, rtxC, hlyA, and ompU. Therefore, it is possible that some of these isolates have the potential to cause gastroenteritis or other infections in humans. We also investigated the relative motility of the isolates and their ability to form biofilms as this is important for V. cholerae survival in the environment. We identified one isolate that forms very robust biofilms, up to 4x that of our laboratory strains. Finally, we investigated the susceptibility of these isolates to a panel of antibiotics. We found that many of the isolates showed decreased susceptibility to some of the antibiotics tested, which could be of concern. While we do not know if these isolates are pathogenic to humans, increased surveillance to better understand the public health risk to the local community should be considered.

Phenotypic and Genotypic Properties of Vibrio cholerae non-O1, non-O139 Isolates Recovered from Domestic Ducks in Germany

Vibrio cholerae non-O1, non-O139 bacteria are natural inhabitants of aquatic ecosystems and have been sporadically associated with human infections. They mostly lack the two major virulence factors of toxigenic V. cholerae serogroups O1 and O139 strains, which are the causative agent of cholera. Non-O1, non-O139 strains are found in water bodies, sediments, and in association with other aquatic organisms. Occurrence of these bacteria in fecal specimens of waterfowl were reported, and migratory birds likely contribute to the long-distance transfer of strains. We investigated four V. cholerae non-O1, non-O139 isolates for phenotypic traits and by whole genome sequencing (WGS). The isolates were recovered from organs of domestic ducks with serious disease symptoms. WGS data revealed only a distant genetic relationship between all isolates. The isolates harbored a number of virulence factors found in most V. cholerae strains. Specific virulence factors of non-O1, non-O139 strains, such as the type III secretion system (TTSS) or cholix toxin, were observed. An interesting observation is that all isolates possess multifunctional autoprocessing repeats-in-toxin toxins (MARTX) closely related to the MARTX of toxigenic El Tor O1 strains. Different primary sequences of the abundant OmpU proteins could indicate a significant role of this virulence factor. Phenotypic characteristics such as hemolysis and antimicrobial resistance (AMR) were studied. Three isolates showed susceptibility to a number of tested antimicrobials, and one strain possessed AMR genes located in an integron. Knowledge of the environmental occurrence of V. cholerae non-O1, non-O139 in Germany is limited. The source of the infection of the ducks is currently unknown. In the context of the ‘One Health’ concept, it is desirable to study the ecology of V. cholerae non-O1, non-O139, as it cannot be excluded that the isolates possess zoonotic potential and could cause infections in humans.

Low Viability of Cholera Toxin-Producing Vibrio cholerae O1 in the Artificial Low Ionic Strength Aquatic Solution

It has been well known that Vibrio cholerae inhabit in environmental water. As many patients infected with cholera toxin-producing V. cholerae O1 (toxigenic V. cholerae O1) emerge in Kolkata, India, it has been thought that toxigenic V. cholerae O1 is easily detected in environmental water in Kolkata. However, we could not isolate toxigenic V. cholerae O1 from environmental water in Kolkata, though NAG Vibrio (generic name of V. cholerae non-O1/non-O139) is constantly detected. To clear the reason for the non-isolation of toxigenic V. cholerae O1, we examined the viability of V. cholera O1 and NAG Vibrios in the artificial low ionic strength aquatic solution. We found that the viability of toxigenic V. cholerae O1 in the solution is low, but that of NAG Vibrios is high. Subsequently, we examined the viability of NAG Vibrios possessing cholera toxin gene (ctx) in the same condition and found that the viability of these NAG Vibrios is low. These results indicate that the existence of ctx in V. cholerae affects the viability of V. cholerae in the aquatic solution used in this experiment. We thought that there was closely relation between the low viability of toxigenic V. cholerae O1 in the artificial low ionic strength aquatic solution and the low frequency of isolation of the strain from environmental water.

Global emergence of environmental non-O1/O139 Vibrio cholerae infections linked with climate change: a neglected research field?

The bacterium Vibrio cholerae is a natural inhabitant of aquatic ecosystems across the planet. V. cholerae serogroups O1 and O139 are responsible for cholera outbreaks in developing countries accounting for 3-5 million infections worldwide and 28.800-130.000 deaths per year according to the World Health Organization. In contrast, V. cholerae serogroups other than O1 and O139, also designated as V. cholerae non-O1/O139 (NOVC), are not associated with epidemic cholera but can cause other illnesses that may range in severity from mild (e.g. gastroenteritis, otitis, etc.) to life-threatening (e.g. necrotizing fasciitis). Although generally neglected, NOVC-related infections are on the rise and represent one of the most striking examples of emerging human diseases linked to climate change. NOVC strains are also believed to potentially contribute to the emergence of new pathogenic strains including strains with epidemic potential as a direct consequence of genetic exchange mechanisms such as horizontal gene transfer and genetic recombination. Besides general features concerning the biology and ecology of NOVC strains and their associated diseases, this review aims to highlight the most relevant aspects related to the emergence and potential threat posed by NOVC strains under a rapidly changing environmental and climatic scenario.

Difference of Phenotype and Genotype Between Human and Environmental: Isolated Vibrio cholerae in Surabaya, Indonesia

Cholera due to Vibrio cholerae has been spreading worldwide, although the reports focusing on Indonesian V. cholerae are few. In this study, in order to investigate how V. cholerae transmitted to human from environment. We extended an epidemiological report that had investigated the genotype of V. cholerae isolated from human pediatric samples and environmental samples. We examined 44 strains of V. cholerae isolated from pediatric diarrhea patients and the environment such as shrimps or oysters collected in three adjacent towns in Surabaya, Indonesia. Susceptibilities were examined for 11 antibiotics. Serotype O1 or O139 genes and pathogenic genes including cholera toxin were detected. Multi-locus sequence typing (MLST) and enterobacterial repetitive intergenic consensus (ERIC)-PCR were also performed to determine genetic diversity of those isolates. Serotype O1 was seen in 17 strains (38.6%) with all pathogenic genes among 44 isolates. Other isolates were non-O1/non-O139 V. cholerae. Regarding antibiotic susceptibilities, those isolates from environmental samples showed resistance to ampicillin (11.4%), streptomycin (9.1%) and nalidixic acid (2.3%) but those isolates from pediatric stools showed no resistance to those 3 kinds of antibiotics. MLST revealed sequence type (ST) 69 in 17 strains (38.6%), ST198 in 3 strains (6.8%) and non-types in 24 strains (54.5%). All the ST69 strains were classified to O1 type with more than 95% similarity by ERIC-PCR, including all 6 (13.6%) isolates from environmental samples with resistance to streptomycin. In conclusion, V. cholerae O1 ST69 strains has been clonally spreading in Surabaya, exhibiting pathogenic factors and antibiotic resistance to streptomycin, especially in the isolates from environment.

Potentially human pathogenic Vibrio spp. in a coastal transect: Occurrence and multiple virulence factors

An increase in human Vibrio spp. infections has been linked to climate change related events, in particular to seawater warming and heatwaves. However, there is a distinct lack of research of pathogenic Vibrio spp. occurrences in the temperate North Sea, one of the fastest warming seas globally. Particularly in the German Bight, Vibrio investigations are still scarce. This study focuses on the spatio-temporal quantification and pathogenic characterization of V. parahaemolyticus, V. vulnificus and V. cholerae over the course of 14 months. Species-specific MPN-PCR (Most probable number - polymerase chain reaction) conducted on selectively enriched surface water samples revealed seasonal patterns of all three species with increased abundances during summer months. The extended period of warm seawater coincided with prolonged Vibrio spp. occurrences in the German Bight. Temperature and nitrite were the factors explaining variations in Vibrio spp. abundances after generalized additive mixed models. The specific detection of pathogenic markers via PCR revealed trh-positive V. parahaemolyticus, pathogenic V. vulnificus (nanA, manIIA, PRXII) and V. cholerae serotype O139 presence. Additionally, spatio-temporally varying virulence profiles of V. cholerae with multiple accessory virulence-associated genes, such as the El Tor variant hemolysin (hlyAET), acyltransferase of the repeats-in-toxin cluster (rtxC), Vibrio 7th pandemic island II (VSP-II), Type III Secretion System (TTSS) and the Cholix Toxin (chxA) were detected. Overall, this study highlights that environmental human pathogenic Vibrio spp. comprise a reservoir of virulence-associated genes in the German Bight, especially in estuarine regions. Due to their known vast genetic plasticity, we point to the possible emergence of highly pathogenic V. cholerae strains. Particularly, the presence of V. cholerae serotype O139 is unusual and needs urgent continuous surveillance. Given the predictions of further warming and more frequent heatwave events, human pathogenic Vibrio spp. should be seriously considered as a developing risk to human health in the German Bight.

Acesso ao Saneamento básico e Incidência de Cólera: uma análise quantitativa entre 2010 e 2015

RESUMO As condições de saneamento básico são um dos principais determinantes nos índices de agravos à saúde humana, principalmente no tocante a doenças infectocontagiosas por veiculação hídrica. Dentre todas, destacamos neste trabalho a cólera: doença entérica causada pelas cepas toxigênicas do Vibrio cholerae (sorogrupos O1 e O139), que é caracterizada por um quadro de acentuada diarreia. O objetivo deste trabalho, por meio de levantamento de dados mundiais de Incidência de Cólera (IC) e percentual populacional de Acesso ao Saneamento (AS), é quantificar, evidenciar e discutir a relação entre esses dois indicadores no período de 2010 a 2015, assim como apontar outros possíveis fatores magnificantes de vulnerabilidade socioambiental para a patologia. No período analisado, foram registrados 1.575.168 casos da doença, com as maiores incidências na região do subcontinente áfrico-asiático e em países isolados nos demais continentes, como, por exemplo, Haiti (América) e Papua Nova Guiné (Oceania), que também apresentaram sérios problemas de acessibilidade a serviços de saneamento. Desta forma, apesar de sugerirmos a análise de outros fatores socioambientais, as condições de saneamento revelaram-se como um determinante expressivo para a incidência da cólera em todas as regiões do mundo.

Potential pathogenicity and antibiotic resistance of aquatic Vibrio isolates from freshwater in Slovakia

This study aimed to evaluate the potential pathogenicity and antibiotic resistance of 31 environmental Vibrio isolates obtained from surface water in southern and eastern Slovakia. Isolates were identified as Vibrio cholerae non-O1/non-O139 and Vibrio metschnikovii by biochemical tests, MALDI biotyping, and 16S RNA gene sequencing. Analysis of the susceptibility to 13 antibacterial agents showed susceptibility of all isolates to ciprofloxacin, trimethoprim/sulfamethoxazole, chloramphenicol, gentamicin, imipenem, tetracyclin, and doxycycline. We recorded high rates of resistance to β-lactams and streptomycin. Investigation of antibiotic resistance showed five different antibiotic profiles with resistance to antibacterials from three classes, but no multidrug resistance was observed. The investigation of the pathogenic potential of V. cholerae isolates showed that neither the cholera toxin coding gene ctxA nor the genes zot (zonula occludens toxin), ace (accessory cholera toxin), and tcpA (toxin-coregulated pilus) were present in any of 31 isolated samples. Gene ompU (outer membrane protein) was confirmed in 80% and central regulatory protein-coding gene toxR in 71% of V. cholerae isolates, respectively. A high prevalence of the hemolysin coding gene hlyA in all V. cholerae was observed. The data point toward the importance of systematic monitoring and comparative studies of potentially pathogenic vibrios in European countries.

Occurrence, Seasonal Distribution, and Molecular Characterization of Vibrio vulnificus, Vibrio cholerae, and Vibrio parahaemolyticus in Shellfish (Mytilus galloprovincialis and Ruditapes decussatus) Collected in Sardinia (Italy)

In this study, we investigated the occurrence, seasonal distribution, and molecular characterization of pathogenic vibrios in Mediterranean mussels (Mytilus galloprovincialis) and grooved carpet shells (Ruditapes decussatus) from two harvesting areas of Sardinia (Italy). Samples collected before and after depuration were submitted for qualitative and quantitative determination of Vibrio spp. Vibrio spp. isolates were presumptively identified by means of biochemical methods. Identification and virulence profile of Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus were performed by molecular methods. The prevalence of Vibrio spp. in M. galloprovincialis and R. decussatus was, respectively, 96 and 77%. The averaged enumeration (mean ± standard deviation) of Vibrio spp. in samples of M. galloprovincialis and R. decussatus collected at the harvesting time was 2.04 ± 0.45 and 2.51 ± 0.65 log CFU/g, respectively. The average contamination levels in samples collected after purification were 2.28 ± 0.58 log CFU/g (M. galloprovincialis) and 2.12 ± 0.67 log CFU/g (R. decussatus). Four potentially pathogenic V. parahaemolyticus isolates (tdh⁺ or trh⁺) were recovered from grooved carpet shells samples. No isolate was tdh⁺/trh⁺. The presence of potentially pathogenic vibrios in Sardinian waters strengthens the need for rational purification practices under controlled conditions to guarantee the protection of consumers.

Virulence, antimicrobial and heavy metal tolerance, and genetic diversity of Vibrio cholerae recovered from commonly consumed freshwater fish

Vibrio cholerae is a leading waterborne pathogen worldwide. Continuous monitoring of V. cholerae contamination in aquatic products and identification of risk factors are crucial for assuring food safety. In this study, we determined the virulence, antimicrobial susceptibility, heavy metal tolerance, and genetic diversity of 400 V. cholerae isolates recovered from commonly consumed freshwater fish (Aristichthys nobilis, Carassius auratus, Ctenopharyngodon idellus, and Parabramis pekinensis) collected in July and August of 2017 in Shanghai, China. V. cholerae has not been previously detected in the half of these fish species. The results revealed an extremely low occurrence of pathogenic V. cholerae carrying the major virulence genes ctxAB (0.0%), tcpA (0.0%), ace (0.0%), and zot (0.0%). However, high incidence of virulence-associated genes was observed, including the RTX toxin gene cluster (rtxA-D) (83.0-97.0%), hlyA (87.8%), hapA (95.0%), and tlh (76.0%). Meanwhile, high percentages of resistance to antimicrobial agents streptomycin (65.3%), ampicillin (44.5%), and rifampicin (24.0%) were observed. Approximately 30.5% of the isolates displayed multidrug resistant (MDR) phenotypes with 42 resistance profiles, which were significantly different among the four fish species (MARI, P = 0.001). Additionally, tolerance of isolates to heavy metals Hg²⁺ (49.3%), Zn²⁺ (30.3%), and Pb²⁺ (12.0%) was observed. The enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR)-based fingerprinting of the 400 V. cholerae isolates revealed 328 ERIC-genotypes, which demonstrated a large degree of genomic variation among the isolates. Overall, the results of this study support the need for food safety risk assessment of aquatic products.

Characterization of Vibrio cholerae O1 isolates responsible for cholera outbreaks in Kenya between 1975 and 2017

Kenya is endemic for cholera with different waves of outbreaks having been documented since 1971. In recent years, new variants of Vibrio cholerae O1 have emerged and have replaced most of the traditional El Tor biotype globally. These strains also appear to have increased virulence, and it is important to describe and document their phenotypic and genotypic traits. This study characterized 146 V. cholerae O1 isolates from cholera outbreaks that occurred in Kenya between 1975 and 2017. Our study reports that the 1975-1984 strains had typical classical or El Tor biotype characters. New variants of V. cholerae O1 having traits of both classical and El Tor biotypes were observed from 2007 with all strains isolated between 2015 and 2017 being sensitive to polymyxin B and carrying both classical and El Tor type ctxB. All strains were resistant to Phage IV and harbored rstR, rtxC, hlyA, rtxA and tcpA genes specific for El Tor biotype indicating that the strains had an El Tor backbone. Pulsed field gel electrophoresis (PFGE) genotyping differentiated the isolates into 14 pulsotypes. The clustering also corresponded with the year of isolation signifying that the cholera outbreaks occurred as separate waves of different genetic fingerprints exhibiting different genotypic and phenotypic characteristics. The emergence and prevalence of V. cholerae O1 strains carrying El Tor type and classical type ctxB in Kenya are reported. These strains have replaced the typical El Tor biotype in Kenya and are potentially more virulent and easily transmitted within the population.

Development of a loop-mediated isothermal amplification assay for Vibrio cholerae O1 and O139

A loop-mediated isothermal amplification assay was developed. It was designed for recognizing Vibrio cholerae O1/O139, where atpA, rfbN, and wfbR genes were adopted. The assay specifically detected the target with sensitivities of 5-67 copies per reaction in 1 h. The assay will aid rapid detection of the cholera bacterium.

Plant virus-based materials for biomedical applications: Trends and prospects

Nanomaterials composed of plant viral components are finding their way into medical technology and health care, as they offer singular properties. Precisely shaped, tailored virus nanoparticles (VNPs) with multivalent protein surfaces are efficiently loaded with functional compounds such as contrast agents and drugs, and serve as carrier templates and targeting vehicles displaying e.g. peptides and synthetic molecules. Multiple modifications enable uses including vaccination, biosensing, tissue engineering, intravital delivery and theranostics. Novel concepts exploit self-organization capacities of viral building blocks into hierarchical 2D and 3D structures, and their conversion into biocompatible, biodegradable units. High yields of VNPs and proteins can be harvested from plants after a few days so that various products have reached or are close to commercialization. The article delineates potentials and limitations of biomedical plant VNP uses, integrating perspectives of chemistry, biomaterials sciences, molecular plant virology and process engineering.

Environmental and Clinical Strains of Vibrio cholerae Non-O1, Non-O139 From Germany Possess Similar Virulence Gene Profiles

Vibrio cholerae is a natural inhabitant of aquatic ecosystems globally. Strains of the serogroups O1 and O139 cause the epidemic diarrheal disease cholera. In Northern European waters, V. cholerae bacteria belonging to other serogroups (designated non-O1, non-O139) are present, of which some strains have been associated with gastrointestinal infections or extraintestinal infections, like wound infections or otitis. For this study, environmental strains from the German coastal waters of the North Sea and the Baltic Sea were selected (100 strains) and compared to clinical strains (10 isolates) that were from patients who contracted the infections in the same geographical region. The strains were characterized by MLST and examined by PCR for the presence of virulence genes encoding the cholera toxin, the toxin-coregulated pilus (TCP), and other virulence-associated accessory factors. The latter group comprised hemolysins, RTX toxins, cholix toxin, pandemic islands, and type III secretion system (TTSS). Phenotypic assays for hemolytic activity against human and sheep erythrocytes were also performed. The results of the MLST analysis revealed a considerable heterogeneity of sequence types (in total 74 STs). The presence of virulence genes was also variable and 30 profiles were obtained by PCR. One profile was found in 38 environmental strains and six clinical strains. Whole genome sequencing (WGS) was performed on 15 environmental and 7 clinical strains that were ST locus variants in one, two, or three alleles. Comparison of WGS results revealed that a set of virulence genes found in some clinical strains is also present in most environmental strains irrespective of the ST. In few strains, more virulence factors are acquired through horizontal gene transfer (i.e., TTSS, genomic islands). A distinction between clinical and environmental strains based on virulence gene profiles is not possible for our strains. Probably, many virulence traits of V. cholerae evolved in response to biotic and abiotic pressure and serve adaptation purposes in the natural aquatic environment, but provide a prerequisite for infection of susceptible human hosts. These findings indicate the need for surveillance of Vibrio spp. in Germany, as due to global warming abundance of Vibrio will rise and infections are predicted to increase.

Investigating the virulence genes and antibiotic susceptibility patterns of Vibrio cholerae O1 in environmental and clinical isolates in Accra, Ghana

Background

Cholera has been endemic in Ghana since its detection in 1970. It has been shown that long-term survival of the bacteria may be attained in aquatic environments. Consequently, cholera outbreaks may be triggered predominantly in densely populated urban areas. We investigated clinical and environmental isolates of Vibrio cholerae O1 in Accra to determine their virulence genes, antibiotic susceptibility patterns and environmental factors maintaining their persistence in the environment.

Methods

Water samples from various sources were analyzed for the presence of V. cholerae O1 using culture methods. Forty clinical isolates from a previous cholera outbreak were included in the study for comparison. Antibiotic susceptibility patterns of the bacteria were determined by disc diffusion. Virulence genes were identified by analyzing genes for ctx, tcpA (tcpA_{El Tor} tcpA_Cl), zot, ompW, rbfO1 and attRS using PCR. Physicochemical characteristics of water were investigated using standard methods. One-way ANOVA and student t - test were employed to analyze the relationship between physicochemical factors and the occurrence of V. cholerae O1.

Results

Eleven V. cholerae O1 strains were successfully isolated from streams, storage tanks and wells during the study period. All isolates were resistant to one or more of the eight antibiotics used. Multidrug resistance was observed in over 97% of the isolates. All isolates had genes for at least one virulence factor. Vibrio cholerae toxin gene was detected in 82.4% of the isolates. Approximately 81.8% of the isolates were positive for tcpA_{El Tor} gene, but also harbored the tcpA_cl gene. Isolates were grouped into thirteen genotypes based on the genes analyzed. High temperature, salinity, total dissolved solids and conductivity was found to significantly correlate positively with isolation of V. cholerae O1. V. cholerae serotype Ogawa biotype El tor is the main biotype circulating in Ghana with the emergence of a hybrid strain.

Conclusions

Multidrug resistant V. cholerae O1 with different genotypes and pathogenicity are present in water sources and co-exist with non O1/O139 in the study area.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3714-z) contains supplementary material, which is available to authorized users.

Ballast water treatment and bacteria: Analysis of bacterial activity and diversity after treatment of simulated ballast water by electrochlorination and UV exposure

Effects of ballast water (BW) treatment by ultra-violet (UV) light and electrochlorination (EC) on survival, activity and diversity of marine bacterioplankton and release of organic matter from cell damage were examined at discharge in a large-scale BW test facility (250 m³ tanks) at Hundested harbour, Denmark. The tests were performed in accordance with the requirements for type approval testing by International Maritime Organization (IMO) and US Coast Guard. After treatment, the water was held in the tanks for one day (EC) before discharge, or 6 days (UV, including also a final UV re-treatment) before discharge. In the discharged and treated water, numbers of viable bacteria and bacterial growth rate had decreased significantly relative to the untreated water, but the total number of bacteria only was reduced in the EC-treated water. After additional storage for up to 10 days in small-scale laboratory incubations, significant regrowth of bacteria was observed after either treatment. Sequencing of 16S rRNA gene amplicons demonstrated that α-Proteobacteria initially were dominant, but γ-Proteobacteria dominated after regrowth. Bacteria used to document BW treatment efficiency (E. coli, Vibrio spp., enterococci) survived both treatments; neither treatment reduced the risk of pathogen dispersal. Concentrations of amino acids in the water were used as indicators of treatment-induced cell damage and demonstrated higher concentrations at discharge, but only after the EC treatments. Our results indicate that activity of bacteria, rather than their abundances, should be used when examining effects by ballast water treatment on microorganisms and that none of the examined treatment technologies could eliminate pathogenic bacteria.

Virulence gene profiles, biofilm formation, and antimicrobial resistance of Vibrio cholerae non-O1/non-O139 bacteria isolated from West Bengal, India

Vibrio cholerae is the causative agent of acute dehydrating diarrhoeal disease cholera. Among 71 V. cholerae non-O1/non-O139 isolates, all yielded negative results for ctxA, ctxB and tcpA genes in PCR assay. Few strains were positive for stn (28.38%), and ompU (31.08%) genes. While all isolates were negative for ace gene, only two were positive for zot gene. All strains expressed toxR and toxT genes. It was also found that all isolates were slime-producer and these were capable of forming moderate to high biofilm. Biofilm formation was controlled positively by the transcriptional regulators VpsR and VpsT and was regulated negatively by HapR, as well as CRP regulatory complex. These isolates were resistant to ampicillin, furazolidone, doxycycline, vancomycin, erythromycin, while these were susceptible to ciprofloxacin, gentamycin, kanamycin, polymixin B, norfloxacin, chloramphenicol, sulphamethoxazole-trimethoprim, tetracycline, nalidixic acid, and streptomycin. Indeed, 69.01% isolates were resistant to multiple antibiotics (MAR: resistance to 3 or more antibiotics). Treatment protocols for cholera patients should be based on local antibiogram data.

Comparison of virulence gene profiles and genomic fingerprints of Vibrio cholerae O1 and non-O1/non-O139 isolates from diarrheal patients in southern Thailand

BACKGROUND

Vibrio cholerae is associated with severe watery diarrheal disease among people in many parts of the world, including the coastal provinces of Southern Thailand. There are relatively few studies focusing on the genetic characterization among V. cholerae isolates in this region. Therefore, this study aimed at exploring the presence of virulence genes and DNA fingerprints among V. cholerae O1 and non-O1/non-O139 isolates obtained from clinical samples in four southern coastal provinces during the period of 2001-2009 (n = 21).

RESULTS

All V. cholerae O1 isolates possessed ctxA, tcpA, zot, ace, hlyA, and vasH genes. However, only hlyA, vcsV2, and vasH genes were detected in the majority of the non-O1/non-O139 isolates. All O1 isolates showed indistinguishable PCR fingerprints by arbitrarily primed (AP)-PCR and enterobacterial repetitive intergenic consensus (ERIC)-PCR regardless of the geographical area and period of isolation. However, the multi-locus variable-number of tandem-repeat analysis (MLVA) could differentiate these O1 isolates (n = 11) into eight profiles. Isolates exhibiting an undistinguished MLVA profile also showed identical pulsed-field gel electrophoresis (PFGE). In addition, the O1 isolates were grouped into the same cluster by all methods used in this study.

CONCLUSIONS

This study demonstrated the presence of virulence genes and genetic diversity among different serogroups of V. cholerae isolates from clinical samples in southern Thailand. V. cholerae O1 isolated over a period of multiple years were genetically related, suggesting that they had a clonal origin, whereas non-O1/non-O139 isolates could have evolved independently.

Vibrio cholerae Transmits Through Water Among the Household Contacts of Cholera Patients in Cholera Endemic Coastal Villages of Bangladesh, 2015-2016 (CHoBI7 Trial)

Recurrent cholera causes significant morbidity and mortality in cholera endemic estuarine areas of Bangladesh. There have been limited studies to investigate the transmission patterns of V. cholerae associated with cholera in Bangladesh. In this study, we characterized V. cholerae serogroup O1 isolated from 30 cholera patients, 76 household contacts, 119 stored drinking water samples, and 119 water source samples in Bakerganj and Mathbaria, two cholera endemic coastal regions in Bangladesh. Results of phenotypic and molecular characterization of V. cholerae isolates (n = 56) confirmed them to be toxigenic belonging to serogroup O1 biotype El Tor (ET), and possessing cholera toxin of the classical biotype (altered ET). Molecular fingerprinting of the V. cholerae O1 of clinical and water origins determined by PFGE of Not-I- digested genomic DNA showed them to be closely related, as the PFGE banding patterns were highly homogenous. Phylogenetic analysis using dendrogram of cholera patients, household contacts, and household groundwater sources showed isolates within households to be clonally linked, suggesting water as an important vehicle of transmission of cholera in the coastal villages of Bangladesh. Transmission of toxigenic V. cholerae O1 through drinking water in cholera endemic rural settings underscores the urgent need for evidence based water, sanitation, and hygiene interventions promoting safe drinking water to prevent morbidity and mortality related to cholera and other enteric infections in Bangladesh.