Molecular characterizations of Vibrio parahaemolyticus in seafood from the Black Sea, Turkey

Predictive Intelligence for Cholera in Ukraine?

Cholera, an ancient waterborne diarrheal disease, remains a threat to public health, especially when climate/weather processes, microbiological parameters, and sociological determinants intersect with population vulnerabilities of loss of access to safe drinking water and sanitation infrastructure. The ongoing war in Ukraine has either damaged or severely crippled civil infrastructure, following which the human population is at risk of health disasters. This editorial highlights a perspective on using predictive intelligence to combat potential (and perhaps impending) cholera outbreaks in various regions of Ukraine. Reliable and judicious use of existing earth observations inspired mathematical algorithms integrating heuristic understanding of microbiological, sociological, and weather parameters have the potential to save or reduce the disease burden.

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.

Longitudinal Study of Total and Pathogenic Vibrio parahaemolyticus (tdh+ and/or trh+) in Two Natural Extraction Areas of Mytilus chilensis in Southern Chile

Vibrio parahaemolyticus is the leading cause of seafood-associated bacterial gastroenteritis worldwide. Although different studies have focused on its pattern of variation over time, knowledge about the environmental factors driving the dynamics of this pathogen, within the Chilean territory, is still lacking. This study determined the prevalence of total and pathogenic V. parahaemolyticus strains (tdh and/or trh genes) in mussels (Mytilus chilensis) collected from two natural growing areas between 2017 and 2018, using selective agar and PCR analysis. V. parahaemolyticus was detected in 45.6% (93/204) of pooled samples from the Valdivia River Estuary. The pathogenic strains carrying the tdh and/or trh gene were detected in 11.8% (24/204): tdh in 9.8% (20/204), trh in 0.5% (1/204), and 1.5% (3/204) presented both genes. In Reloncaví Fjord, V. parahaemolyticus was detected in 14.4% (30/209) of the samples, pathogenic V. parahaemolyticus carrying the trh gene was detected in 0.5% (1/209) of the samples, while the tdh gene was not detected in the samples from this area. The total count of mauve-purple colonies typical of V. parahaemolyticus on CHROMagar was positively associated by multivariate analysis with area, water temperature, and salinity. Similarly, V. parahaemolyticus detection rates by PCR had a positive correlation with the area and water temperature. The chances of detecting total V. parahaemolyticus in the Valdivia River Estuary are significantly higher than in the Reloncaví Fjord, but inversely, during spring-summer months, the interaction factor between the area and temperature indicated that the chances of detecting V. parahaemolyticus are higher in the Reloncaví Fjord. Interestingly, this period coincides with the season when commercial and natural-growing shellfish are harvested. On the other hand, pathogenic V. parahaemolyticus tdh+ was significantly correlated with an increase of water temperature. These environmental parameters could be used to trigger a warning on potential hazard, which would influence human health and economic losses in aquaculture systems.

Virulence, resistance, and genetic diversity of Vibrio parahaemolyticus recovered from commonly consumed aquatic products in Shanghai, China

Vibrio parahaemolyticus can cause severe gastroenteritis, septicaemia and even death in humans. Continuous monitoring of V. parahaemolyticus contamination in aquatic products is imperative for ensuring food safety. In this study, we isolated and characterized 561 V. parahaemolyticus strains recovered from 23 species of commonly consumed shellfish, crustaceans, and fish collected in July and August of 2017 in Shanghai, China. The bacterium was not isolated from two fish species Carassius auratus and Parabramis pekinensis. The results revealed a very low occurrence of pathogenic V. parahaemolyticus carrying the toxin genes trh (0.2%) and tdh (0.0%). However, high percentages of resistance to the antimicrobial agents ampicillin (93.0%), rifampin (82.9%), streptomycin (75.4%) and kanamycin (50.1%) were found. A high incidence of tolerance to the heavy metals Hg²⁺ (74.7%) and Zn²⁺ (56.2%) was also observed in the isolates. ERIC-PCR-based fingerprinting of MDR isolates (77.5%) revealed 428 ERIC-genotypes, demonstrating remarkable genetic variation among the isolates. The results of this study support the urgent need for food safety risk assessment of aquatic products.

Characterisation of Vibrio Species from Surface and Drinking Water Sources and Assessment of Biocontrol Potentials of Their Bacteriophages

The aim of this study was to characterise Vibrio species of water samples collected from taps, boreholes, and dams in the North West province, South Africa, and assess biocontrol potentials of their bacteriophages. Fifty-seven putative Vibrio isolates were obtained on thiosulfate-citrate-bile-salt-sucrose agar and identified using biochemical tests and species-specific PCRs. Isolates were further characterised based on the presence of virulence factors, susceptibility to eleven antibiotics, and biofilm formation potentials. Twenty-two (38.60%) isolates were confirmed as Vibrio species, comprising V. harveyi (45.5%, n = 10), V. parahaemolyticus (22.7%, n = 5), V. cholerae (13.6%, n = 3), V. mimicus (9.1%, n = 2), and V. vulnificus (9.1%, n = 2). Three of the six virulent genes screened were positively amplified; four V. parahaemolyticus possessed the tdh (18.18%) and trh (18.18%) genes, while the zot gene was harboured by 3 V. cholerae (13.64%) and one V. mimicus (4.55%) isolate. Isolates revealed high levels of resistance to cephalothin (95.45%), ampicillin (77.27%), and streptomycin (40.91%), while lower resistances (4.55%–27.27%) were recorded for other antimicrobials. Sixteen (72.7%) isolates displayed multiple antibiotic-resistant properties. Cluster analysis of antibiotic resistance revealed a closer relationship between Vibrio isolates from different sampling sites. The Vibrio species displayed biofilm formation potentials at 37°C (63.6, n = 14), 35°C (50%, n = 11), and 25°C (36.4%, n = 8). Two phages isolated in this study (vB_VpM_SA3V and vB_VcM_SA3V) were classified as belonging to the family Myoviridae based on electron microscopy. These were able to lyse multidrug-resistant V. parahaemolyticus and V. cholerae strains. These findings not only indicate the presence of antibiotic-resistant virulent Vibrio species from dam, borehole, and tap water samples that could pose a health risk to humans who either come in contact with or consume water but also present these lytic phages as alternative agents that can be exploited for biological control of these pathogenic strains.

Occurrence and Identification of Pathogenic Vibrio Contaminants in Common Seafood Available in a Chinese Traditional Market in Qingdao, Shandong Province

The investigation of the causative agents for foodborne diseases and subsequent development of preventive steps to control the outbreak and related economic loss is the basic goal and priority of a rational food safety program. The entero-pathogenic Vibrio spp., which are Gram negative bacteria inhabiting estuarine ecosystems, are the major cause of foodborne illness associated with the consumption of raw or undercooked contaminated seafood or shellfish. To survey the Vibrio contamination in sea snails (Neptunea cumingi Crosse and Busycon canaliculatu), a total of 20 samples were collected from traditional market, at Qingdao city in Shandong province, China and analyzed for Vibrio species contamination. Presumptive-positive colonies grown on a specific Vibrio agar-based medium were picked and identified by the VITEK^TM. Vibrio alginolyticus, V. parahaemolyticus, and V. vulgaris were isolated and identified in 11, 8, and 2 seafood samples, respectively. Among the 8 isolates of V. parahaemolyticus. The V. parahaemolyticus isolates were further tested for the tdh, trh, and tlh virulence factors. All the V. parahaemolyticus isolates were tlh-positive, however, all of them were tdh-negative. Interestingly 2 V. parahaemolyticus isolates were positive for trh virulence factor. These results indicated that there is a high incidence of V. alginolyticus and V. parahaemolyticus in sea snails. Therefore, food safety regulations for fishery auction markets should be established to control these species in addition to other Vibrio pathogenic contaminants. Our study provides the first evidence for the prevalence of Vibrio spp. in sea snail samples from traditional market in the Qingdao province of China.

Genetic and virulence characterisation of Vibrio parahaemolyticus isolated from Indian coast

BACKGROUND

V. parahaemolyticus is autochthonous to the marine environment and causes seafood-borne gastroenteritis in humans. Generally, V. parahaemolyticus recovered from the environment and/or seafood is thought to be non-pathogenic and the relationship between environmental isolates and acute diarrhoeal disease is poorly understood. In this study, we explored the virulence potential of environmental V. parahaemolyticus isolated from water, plankton and assorted seafood samples collected from the Indian coast.

RESULTS

Twenty-two V. parahaemolyticus isolates from seafood harboured virulence associated genes encoding the thermostable-direct haemolysin (TDH), TDH-related haemolysin (TRH), and Type 3 secretion systems (T3SS) and 95.5% of the toxigenic isolates had pandemic strain attributes (toxRS/new+). Nine serovars, with pandemic strain traits were newly identified and an O4:K36 tdh-trh+V. parahaemolyticus bearing pandemic marker gene was recognised for the first time. Results obtained by reverse transcription PCR showed trh, T3SS1 and T3SS2β to be functional in the seafood isolates. Moreover, the environmental strains were cytotoxic and could invade Caco-2 cells upon infection as well as induce changes to the tight junction protein, ZO-1 and the actin cytoskeleton.

CONCLUSION

Our study provides evidence that environmental isolates of V. parahaemolyticus are potentially invasive and capable of eliciting pathogenic characteristics typical of clinical strains and present a potential health risk. We also demonstrate that virulence of this pathogen is highly complex and hence draws attention for the need to investigate more reliable virulence markers in order to distinguish the environmental and clinical isolates, which will be crucial for the pathogenomics and control of this pathogen.

Vibrio parahaemolyticus flagellin induces cytokines expression via toll-like receptor 5 pathway in orange-spotted grouper, Epinephelus coioides

Vibrio parahaemolyticus is the major pathogen of vibriosis in aquatic animals and causes inflammation that may be related to tissue damage. Here, we have established a V. parahaemolyticus flagellin stimulation model using grouper spleen (GS) cell line. Purified V. parahaemolyticus flagellin was used to stimulate GS cells. Our results showed that the mRNA levels of orange-spotted grouper (Epinephelus coioides) toll-like receptor 5M (EcTLR5M), EcTLR5S and downstream cytokines, such as interferon-γ2 (IFN-γ2), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), were all significantly increased after stimulation with V. parahaemolyticus flagellin in GS cells. Gene silencing of the EcTLR5M and EcTLR5S in GS cells by using small interfering RNA resulted in suppression of the V. parahaemolyticus flagellin-induced cytokines expression. We further demonstrated that activation of both mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) were required for cytokines expression. We observed that the phosphorylation of NF-κB inhibitor-α (IκBα), extracellular signal-regulated kinase (ERK) and p38 were induced following treatment with flagellin. Additionally, most of p65, a NF-κB subunit, was found to translocate to the nucleus after 60 min stimulation. Overall, our results suggest that V. parahaemolyticus flagellin influences cytokines expression, such as IFN-γ2, IL-6 and TNF-α, via EcTLR5s recognition and MAPKs/NF-κB signaling pathway activation in GS cells.

A simple, portable, electrochemical biosensor to screen shellfish for Vibrio parahaemolyticus

An earlier electrochemical mechanism of DNA detection was adapted and specified for the detection of Vibrio parahaemolyticus in real samples. The reader, based on a screen printed carbon electrode, was modified with polylactide-stabilized gold nanoparticles and methylene blue was employed as the redox indicator. Detection was assessed using a microprocessor to measure current response under controlled potential. The fabricated sensor was able to specifically distinguish complementary, non-complementary and mismatched oligonucleotides. DNA was measured in the range of 2.0 × 10⁻⁸–2.0 × 10⁻¹³ M with a detection limit of 2.16 pM. The relative standard deviation for 6 replications of differential pulse voltammetry (DPV) measurement of 0.2 µM complementary DNA was 4.33%. Additionally, cross-reactivity studies against various other food-borne pathogens showed a reliably sensitive detection of the target pathogen. Successful identification of Vibrio parahaemolyticus (spiked and unspiked) in fresh cockles, combined with its simplicity and portability demonstrate the potential of the device as a practical screening tool.

Occurrence of Virulence Genes Associated with Human Pathogenic Vibrios Isolated from Two Commercial Dusky Kob (Argyrosmus japonicus) Farms and Kareiga Estuary in the Eastern Cape Province, South Africa

Background: Seafood-borne Vibrio infections, often linked to contaminated seafood and water, are of increasing global public health concern. The aim of this study was to evaluate the prevalence of human pathogenic vibrios and their associated virulence genes isolated from fish and water samples from 2 commercial dusky kob farms and Kareiga estuary, South Africa. Methods: A total of 200 samples including dusky kob fish (n = 120) and seawater (n = 80) were subjected to Vibrio screening on thiosulfate-citrate-bile salts-sucrose agar (TCBS). Presumptive isolates were confirmed and delineated to V. cholerae, V. parahaemolyticus, V. vulnificus, and V. fluvialis by PCR. Various pathogenic gene markers were screened: V. parahaemolyticus (trh and tdh), V. vulnificus (vcgE and vcgC) and V. fluvialis (stn, vfh,hupO, vfpA). Restriction Fragment Length Polymorphism (RFLP) of the vvhA gene of V. vulnificus strains was performed to determine the associated biotypes. Results: Total Vibrio prevalence was 59.4% (606/1020) of which V. fluvialis was the most predominant 193 (31.85%), followed by Vibrio vulnificus 74 (12.21%) and V. parahaemolyticus 33 (5.45%). No V. cholerae strain was detected. One of the V. parahaemolyticus strains possessed the trh gene 7 (9.46%) while most (91.9%; 68/74) V. vulnificus isolates were of the E-type genotype. V. fluvialis virulence genes detected were stn (13.5%), hupO (10.4%) and vfpA (1.0%). 12.16% (9/74) of V. vulnificus strains exhibited a biotype 3 RFLP pattern. Conclusions: This is the first report of potentially pathogenic vibrios from healthy marine fish in the study area, and therefore a public health concern.

Vibrio Parahaemolyticus: A Review on Distribution, Pathogenesis, Virulence Determinants and Epidemiology

Vibrio parahaemolyticus is a Gram-negative, halophilic bacterium isolated from marine environments globally. After the consumption of contaminated seafood, V. parahaemolyticus causes acute gastroenteritis. To initiate infection, a wide range of virulence factors are required. A complex group of genes is known to participate in the pathogenicity of V. parahaemolyticus; however, to understand the full mechanism of infection, extensive research is yet required. V. parahaemolyticus has become the leading cause of seafood-related gastroenteritis in Japan, the United States and several other parts of the world. In addition, outbreaks caused by the pandemic clone of this organism are escalating and spreading universally. To minimize the risk of V. parahaemolyticus infection and warrant the safety of seafood, collaboration between governments and scientists is required. We herein provide an updated review of the pathogenicity determinants and distribution of V. parahaemolyticus to deliver a better understanding of the significance of V. parahaemolyticus and its host-pathogen interactions.