Seasonal Prevalence of Enteropathogenic Vibrio and Their Phages in the Riverine Estuarine Ecosystem of South Bengal

Vibrio cholerae in Water Environments: A Systematic Review and Meta-Analysis

Vibrio cholerae is a water-borne pathogen transmitted via the faecal-oral route, with water being a major vehicle for infection. The pathogen has caused seven pandemics in history, with contaminated water identified as the infection source. Seasonal outbreaks, claiming approximately 21,000-143,000 lives yearly, are facilitated by contaminated water environments. This systematic review, therefore, determined the prevalence of V. cholerae in water environments. A comprehensive literature search was conducted in PubMed, Web of Science, and SCOPUS. After the screening process, 87 articles were included in our study. RStudio version 4.3.3 was used in conducting our meta-analysis with the data subjected to the random-effects model. The included articles were from 38 countries, which spanned 6 continents. The prevalences of V. cholerae in water environments were as follows: drinking water (15.69%), untreated sewage (57.26%), treated sewage (95.18%), surface water (41.95%), groundwater (26.23%), and others (20.81%). Continental prevalence revealed the following: Australia (85.00%), North America (66.60%), Africa (42.07), South America (39.32%), Asia (29.28%), and Europe (24.48%). There is a high prevalence of V. cholerae in water environments. More effective water treatment methods are needed to drastically reduce its prevalence to insignificant levels, especially in treated drinking water.

Genomic Insight into Vibrio Isolates from Fresh Raw Mussels and Ready-to-Eat Stuffed Mussels

Consuming raw or undercooked mussels can lead to gastroenteritis and septicemia due to Vibrio contamination. This study analyzed the prevalence, density, species diversity, and molecular traits of Vibrio spp. in 48 fresh raw wild mussels (FRMs) and 48 ready-to-eat stuffed mussels (RTE-SMs) through genome analysis, assessing health risks. The results showed Vibrio prevalence rates of 12.5% in FRMs and 4.2% in RTE-SMs, with V. alginolyticus as the most common species (46.7%). It was determined that the seasonal distribution of Vibrio spp. prevalence in the samples was higher in the summer months. The genome sizes of the Vibrio spp. ranged from approximately 3.9 to 6.1 Mb, with the GC contents varying between 41.9% and 50.4%. A total of 22 virulence factor (VF) classes and up to six antimicrobial resistance (AMR) genes were detected in different Vibrio species. The presence of nine different biosynthetic gene clusters (BGCs), 27 prophage regions, and eight CRISPR/Cas systems in 15 Vibrio strains provides information about their potential pathogenicity, survival strategies, and adaptation to different habitats. Overall, this study provides a comprehensive understanding of the genomic diversity of Vibrio spp. isolated from FRM and RTE-SM samples, shedding light on the prevalence, pathogenicity, and toxicity mechanisms of Vibrio-induced gastroenteritis.

Existence of Thermotolerant and Salt-Loving Diarrheagenic Vibrio alginolyticus in Non-Saline Potable Water System: A Novel Finding from India

We present a novel report of abundance of halophilic Vibrio alginolyticus with thermotolerant and enterotoxigenic characteristics from community water system of an inland-focus of India causing diarrheal outbreak as an index pathogen. Though, Vibrio alginolyticus causing diarrhea after exposure to marine water and consumption of seafood was reported globally, its existence in non-saline drinking-water sources with pathogenic viability was unknown. A 'matched-pair-case-control' study identified the primary source of V. alginolyticus infection as 'tap-water' distributed by the municipality, used for drinking (MOR: 8.33; 95% CI 2.51-27.6) and household chores (MOR: 3.75; 95% CI 1.24-11.3). Cardinal toxin gene 'tdh' and other pathogenicity markers viz.tlh, vppC, toxR, VPI, T3SS1 and sxt were detected in V. alginolyticus isolates. Expression potential of the hemolytic genes are demonstrated by hemolysis assay and transcriptome analysis. Altogether 30.55% of isolates exhibited strong hemolytic potential in vitro. RT-PCR revealed uninterrupted virulence gene expression in outbreak strains under heat stress. Surprisingly, ~ 100% of V. alginolyticus from the outbreak focus were sensitive/partially sensitive to all group of antibiotics except β-lactums, carbapenem and quinolones. High drug-sensitivity suggested lack of previous human gut exposure and indicated a fresh dissemination from the environmental niche to the community domain. The maximum likelihood phylogeny depicted multiple clades in V. alginolyticus strains from Pan India sources. Isolated outbreak strains shared common ancestry with the strains from nearby riverine system, a source of 'drinking water' supplied to the affected community, confirming its environmental origin. V. alginolyticus, traditionally a fish-pathogen, is steadily gaining an emerging epidemiological relevance alongside other waterborne diarrheagenic bacteria and its 'thermotolerant' attribute poses additional threat under the canvas of climate change.

Global prevalence patterns and distribution of Vibrio cholerae: A systematic review and meta-analysis of 176,740 samples

This global systematic review and meta-analysis of Vibrio cholerae prevalence, covering environmental, food, animal, and human samples, analysed 111 studies from five databases. The meta-analysis, adhering to standard reporting guidelines, revealed a pooled prevalence of 10.6 % (95 % CI; 8.2 - 13.5; I2 = 99.595 %, p < 0.001) from 176,740 samples, including 27,219 cholera cases. Despite significant publication bias (Egger's test, p = 0.00018), prevalence estimate remained stable in leave-one-out analysis. Subgroup analysis showed prevalence varied by region, with Indonesia highest (55.2 %) and Jordan lowest (0.2 %). Asia continent had the highest prevalence (13.9 %), followed by South America (12.1 %), and lowest in Europe (3.8 %). Environmental samples exhibited the highest prevalence (24.9 %), while human samples had the lowest (7.1 %). The pervasive presence of V. cholerae in environmental resources highlights the persistent risk of global cholera outbreaks, necessitating urgent proactive measures and ongoing surveillance for effective cholera control.

Temporal Dynamics and Contribution of Phage Community to the Prevalence of Antibiotic Resistance Genes in a Full-Scale Sludge Anaerobic Digestion Plant

Anaerobic digestion (AD) is an important biological resource recovery process, where microorganisms play key roles for material transformation. There has been some knowledge about the prokaryotic community and antibiotic resistance genes (ARGs) in AD, but there has been very limited knowledge of phages. In this study, samples from a full-scale AD plant were collected over 13 months, sequenced, and analyzed for viral and prokaryotic metagenomes. Totally, 3015 viral operational taxonomic units (vOTUs) were detected, mostly assigned to Caudoviricetes. The phage community had faster temporal variation than the prokaryotic community. Warm seasons harbored a higher abundance of both temperate phages and broad host-range phages. Seven ARGs of 6 subtypes were carried by 20 vOTUs, a representative ermT gene was synthesized and expressed, and the resistance activity in the host was examined, confirming the real activity of virus-carried ARGs in the AD process. Some of the ARGs were horizontally transferred between the phage and prokaryotic genomes. However, phage infection was not found to contribute to ARG transfer. This study provided an insight into the ecological patterns of the phage community, confirmed the antibiotic resistance activity of virus-carried ARGs, evaluated the contribution of phages on the ARG prevalence, and laid the foundation for the control strategies of the community and antibiotic resistance in the AD process.

Incidence of antibiotic resistance genotypes of Vibrio species recovered from selected freshwaters in Southwest Nigeria

Vibrio species are classified as potent hazards because of their tendency to effect serious diseases like cholera and other gastrointestinal ailments in humans, as well as vibriosis in fish. A total of 144 freshwater samples were aseptically collected monthly across four rivers (Asejire, Ona, Dandaru and Erinle rivers) over a 12-month period from which Vibrio spp. were isolated using culture procedures, confirmed by means of biochemical test as well as Polymerase Chain Reaction (PCR) assay and further characterized for their phenotypic antibiotic susceptibilities and relevant antimicrobial resistant determinants by PCR. Three hundred and fifteen (58%) isolates confirmed across the sampled sites (Asejire = 75, Dandaru = 87, Eleyele = 72, Erinle = 81) showed high resistance against erythromycin-95%, Sulphamethoxazole-94%, rifampicin-92%, doxycycline-82%, tetracycline-75%, amoxicillin-45%, cephalothin-43% and varied susceptibilities to other antibiotics. The multiple antibiotic resistance indices of 97% of the Vibrio isolates were above the 0.2 threshold limit with MAR phenotype pattern E-SUL-RF-TET-DOX (0.38) found to be the most prevalent pattern among the isolates. The distributions of resistance determinant of the tested antibiotics were revealed as follows: sulII 33%, sulI 19% (sulfonamides); bla_OXA 27%, ampC 39%, bla_pse 11% (beta-lactams); tetA 28%, tetE 20%, tet39 8%, (tetracyclines) and strA 39%. aacC2 24%, aphA1 14% (aminoglycosides). Strong positive associations were observed among tetA, sulI, tetE and sulII. This study raises concerns as these selected rivers may contribute to the environmental spread of waterborne diseases and antibiotic resistance genes. Therefore, we recommend environmental context-tailored strategies for monitoring and surveillance of resistance genes so as to safeguard the environment from becoming reservoirs of virulent and infectious Vibrio species.

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.

Molecular Detection and Distribution of Six Medically Important Vibrio spp. in Selected Freshwater and Brackish Water Resources in Eastern Cape Province, South Africa

Water resources contaminated with pathogenic Vibrio species are usually a source of devastating infection outbreaks that have been a public health concern in both developed and developing countries over the decades. The present study assessed the prevalence of six medically significant Vibrio species in some water resources in Eastern Cape Province, South Africa for 12 months. We detected vibrios in all the 194 water samples analyzed using polymerase chain reaction (PCR). The prevalence of Vibrio cholerae, Vibrio mimicus, Vibrio fluvialis, Vibrio vulnificus, Vibrio alginolyticus, and Vibrio parahaemolyticus in freshwater samples was 34, 19, 9, 2, 3, and 2%, and that in brackish water samples was 44, 28, 10, 7, 46, and 51%, respectively. The population of the presumptive Vibrio spp. isolated from freshwater (628) and brackish water (342) samples that were confirmed by PCR was 79% (497/628) and 85% (291/342), respectively. Twenty-two percent of the PCR-confirmed Vibrio isolates from freshwater (n = 497) samples and 41% of the PCR-confirmed Vibrio isolates from brackish water samples (n = 291) fall among the Vibrio species of interest. The incidences of V. cholerae, V. mimicus, V. fluvialis, V. vulnificus, V. alginolyticus, and V. parahaemolyticus amidst these Vibrio spp. of interest that were recovered from freshwater samples were 75, 14, 4, 6, 1, and 1%, whereas those from brackish water samples were 24, 7, 3, 3, 47, and 18%, respectively. Our observation during the study suggests pollution as the reason for the unusual isolation of medically important vibrios in winter. Correlation analysis revealed that temperature drives the frequency of isolation, whereas salinity drives the composition of the targeted Vibrio species at our sampling sites. The finding of the study is of public health importance going by the usefulness of the water resources investigated. Although controlling and preventing most of the factors that contribute to the prevalence of medically important bacteria, such as Vibrio species, at the sampling points might be difficult, regular monitoring for creating health risk awareness will go a long way to prevent possible Vibrio-related infection outbreaks at the sampling sites and their immediate environment.

Development of an advanced DNA biosensor for pathogenic Vibrio cholerae detection in real sample

Due to the epidemics of emerging microbial diseases worldwide, the accurate and rapid quantification of pathogenic bacteria is extremely critical. In this work, a highly sensitive DNA-based electrochemical biosensor has been developed to detect Vibrio cholerae using gold nanocube and 3-aminopropyltriethoxysilane (APTES) modified glassy carbon electrode (GCE) with DNA carrier matrix. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) experiments were performed to interrogate the proposed sensor at each stage of preparation. The biosensor has demonstrated high sensitivity with a wide linear response range to target DNA from 10^-8 to 10^-14 (R²= 0.992) and 10^-14 to 10^-27 molL^-1 (R²= 0.993) with a limit of detection (LOD) value of 7.41 × 10^-30 molL^-1 (S/N = 5). The biosensor also exhibits a selective detection behavior in bacterial cultures that belong to the same and distant genera. Moreover, the proposed sensor can be used for six consecutive DNA assays with a repeatability relative standard deviations (RSD) value of 5% (n = 5). Besides, the DNA biosensor shows excellent recovery for detecting V. cholerae in poultry feces, indicating that the designed biosensor could become a powerful tool for pathogenic microorganisms screening in clinical diagnostics, food safety, and environmental monitoring.

Enteric viruses, somatic coliphages and Vibrio species in marine bathing and non-bathing waters in Italy

Microbial safety of recreational waters is a significant public health issue. In this study we assessed the occurrence and quantity of enteric viruses in bathing and non-bathing waters in Italy, in parallel with microbial faecal indicators, somatic coliphages and Vibrio spp. Enteric viruses (aichivirus, norovirus and enterovirus) were detected in 55% of bathing water samples, including samples with bacterial indicator concentrations compliant with the European bathing water Directive. Aichivirus was the most frequent and abundant virus. Adenovirus was detected only in non-bathing waters. Somatic coliphages were identified in 50% bathing water samples, 80% of which showed simultaneous presence of viruses. Vibrio species were ubiquitous, with 9 species identified, including potential pathogens (V. cholerae, V. parahaemoylticus and V. vulnificus). This is the first study showing the occurrence and high concentration of Aichivirus in bathing waters and provides original information, useful in view of a future revision of the European Directive.

Fatal case of necrotising fasciitis due to Vibrio vulnificus in a patient with alcoholic liver disease and diabetes mellitus

Vibrio vulnificus is a halophilic Vibrio found globally. They are thought to be normal microbiome in the estuaries along the coasts associated with seawater and seashells. Infection usually results from consumption of raw oysters or shellfish or exposure of broken skin or open wounds to contaminated salt or brackish water. Clinical manifestations range from gastroenteritis to skin and subcutaneous infection and primary sepsis. Pathogen has the ability to cause infections with significant mortality in high-risk populations, including patients with chronic liver disease, immunodeficiency, diabetes mellitus and iron storage disorders. There is often a lack of clinical suspicion in cases due to Vibrio vulnificus leading to delay in treatment and subsequent mortality. Herein we report a case of necrotising fasciitis in a diabetic patient with alcoholic liver disease caused by Vibrio vulnificus which ended fatally.

High-Resolution Temporal and Spatial Patterns of Virome in Wastewater Treatment Systems

Wastewater treatment plants (WWTPs) are considered reservoirs of viruses, but the diversity and dynamic changes of viruses are not well understood. In this study, we recovered 8478 metagenomic viral contigs (mVCs; >5 kb) from two WWTPs (Shatin, 2806; Shek Wu Hui, 5672) in Hong Kong. Approximately 60% of the mVCs were poorly covered (<35% of genes in identified mVCs) by the current NCBI and IMG/VR viral databases. The temporal profile of the newly identified mVCs among 98 Shatin AS samples collected monthly (for approximately 9 years) revealed the presence of periodic dynamics at an interval of approximately one year (341 days). The spatial distribution pattern of the virome in the wastewater treatment systems showed that shared viral clusters (viral populations categorized based on shared gene content and network analysis) can be globally found among similar samples of wastewater treatment systems, indicating the presence of core viral communities among geographically isolated wastewater treatment systems. These results not only supplemented the current virome database of engineered systems but also, to some extent, expanded the understanding of long-term cyclical development and spatial distributions of viral communities in wastewater treatment systems.

Waterborne outbreaks in diarrhoea endemic foci of India: a longitudinal exploration and its implications

Diarrhoea remains a global public health enigma raising deep concerns for the health planners since contaminated potable water often spoils the community health structure. We hereby report a 6-year odd continuing outbreak surveillance report based on potable water indices, during which 264 water samples were screened from different districts of West Bengal, India. Samples were analysed for the presence of different enteropathogenic bacterial species by conventional molecular tools and their sensitivity to antibiotics. 78.03% samples were positive for enteropathogenic bacterial organisms and 75% samples harbored Coliform. 45.45, 12.12, and 4.16% samples were positive for E.coli, V. cholerae, and V. mimicus, respectively. Diarrhoeagenic E.coli 7 EPEC, 10 ETEC, and 2 EIEC were isolated along with 2 V. cholerae O1 Ogawa (ctxA and tcpA ElTor positive), one each from tube well and pond. Interestingly, 4 V.cholerae non-O1/non-O139 also harbored hlyA gene. The detection of toxin genes among this bacterial pool of sampled water indicates the fallout of the potable water sources, thus enabling us to establish that it is none other than the contaminated potable water system which often wreaks havoc in the south Bengal diarrhoeal menace. The consequences are further complicated by the presence of drug-resistant pathogenic bacterial pool to fluoroquinolone, beta-lactams, and cephalosporins, in the accessible potable water, with threats of outbreaks exploding into an epidemic, given suitable environment, poor sanitation, and unhygienic practices. Therefore, we strongly recommend re-modelling of 'point-of-use water disinfection' measures and adequate personal hygiene for healthier community life.

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.

Application of a paper based device containing a new culture medium to detect Vibrio cholerae in water samples collected in Haiti

Cholera is now considered to be endemic in Haiti, often with increased incidence during rainy seasons. The challenge of cholera surveillance is exacerbated by the cost of sample collection and laboratory analysis. A diagnostic tool is needed that is low cost, easy-to-use, and able to detect and quantify Vibrio cholerae accurately in water samples within 18-24h, and perform reliably in remote settings lacking laboratory infrastructure and skilled staff. The two main objectives of this study were to develop and evaluate a new culture medium embedded in a new diagnostic tool (PAD for paper based analytical device) for detecting Vibrio cholerae from water samples collected in Haiti. The intent is to provide guidance for corrective action, such as chlorination, for water positive for V. cholerae epidemic strains. For detecting Vibrio cholerae, a new chromogenic medium was designed and evaluated as an alternative to thiosulfate citrate bile salts sucrose (TCBS) agar for testing raw water samples. Sensitivity and specificity of the medium were assessed using both raw and spiked water samples. The Vibrio cholerae chromogenic medium was proved to be highly selective against most of the cultivable bacteria in the water samples, without loss of sensitivity in detection of V. cholerae. Thus, reliability of this new culture medium for detection of V. cholerae in the presence of other Vibrio species in water samples offers a significant advantage. A new paper based device containing the new chromogenic medium previously evaluated was compared with reference methods for detecting V. cholerae from spiked water sample. The microbiological PAD specifications were evaluated in Haiti. More precisely, a total of 185 water samples were collected at five sites in Haiti, June 2014 and again in June 2015. With this new tool, three V. cholerae O1 and 17 V. cholerae non-O1/O139 strains were isolated. The presence of virulence-associated and regulatory genes, including ctxA, zot, ace, and toxR, was confirmed using multiplex PCR. The three V. cholerae O1 isolates were positive for three of the four virulence-associated and regulatory genes. Twelve of the V. cholerae non-O1/O139 isolates were found to carry toxR, but none were ctxA+, zot+, or ace+. However, six of the V. cholerae non-O1/O139 isolates were resistant to penicillin, ampicillin, trimethoprim/sulfamethoxazole, nalidixic acid, and ciprofloxacin. The paper based analytical device (PAD) provides advantages in that standard culture methods employing agar plates are not required. Also, intermediary isolation steps were not required, including transfer to selective growth media, hence these steps being omitted reduced time to results. Furthermore, experienced technical skills also were not required. Thus, PAD is well suited for resource-limited settings.