Recent cholera outbreaks in many countries in the Middle East and North Africa (MENA) region have raised public health concerns and focused attention on the genus Vibrio. However, the epidemiology of Vibrio species in humans, water, and seafood is often anecdotal in this region. In this review, we screened the literature and provided a comprehensive assessment of the distribution and antibiotic resistance properties of Vibrio species in different clinical and environmental samples in the region. This review will contribute to understanding closely the real burden of Vibrio species and the spread of antibiotic-resistant strains in the MENA region. The overall objective is to engage epidemiologists, sanitarians and public health stakeholders to address this problem under the One-health ethos.
The Vibrio genus contains many bacterial species normally found in freshwater, estuaries and marine environments. Some of these species can be transmitted by water and food and can make people severely ill. For instance, some groups of the bacterium Vibrio cholerae (serogroups O1 and O139) can cause serious watery diarrhea called cholera. Other pathogenic Vibrio bacteria can cause other types of infections such as gastroenteritis and wound infections. Some of these bacteria are becoming increasingly resistant to antibiotics, which will threaten and complicate therapy. This review discusses the occurrence and antibiotic resistance of different important Vibrio species in the Middle East and North Africa (MENA) region.

OBJECTIVE: Dermaseptins are one of the main families of antimicrobial peptides (AMPs) derived from the skin secretions of Hylidae frogs. Among them, dermaseptin S4 (DS4) is characterized by its broad-spectrum of activity against bacteria, protozoa, and fungi. In this study, the physicochemical properties of the native peptide DS4 (1-28) and two derivatives [DS4 (1-28)a and DS4 (1-26)a] isolated from the skin of the frog Phyllomedusa sauvagii were investigated and their antimicrobial properties against two marine pathogenic bacteria (Vibrio harveyi and Vibrio anguillarum) were examined.
RESULTS: The results indicate that the peptide DS4 (1-26)a has high-antibacterial activity against the tested strains and low-hemolytic activity (<30% lysis at the highest tested concentration of 100 µg/mL) compared to the other two peptides tested. In addition, all three peptides affect the membrane and cell wall integrity of both pathogenic bacteria, causing leakage of cell contents, with DS4 (1-26)a having the most severe impact. These skills were corroborated by transmission electron microscopy and by the variation of cations in their binding sites due to the effects caused by the AMPs.
CONCLUSIONS: These results suggest that DS4 and its derivatives, in particular the truncated and amidated peptide DS4 (1-26)a could be effective in the treatment of infections caused by these marine pathogenic bacteria. Future studies are required to validate the use of DS4  in vivo for the prevention of bacterial diseases in fish.

The pathogen recognition system involves receptors and genes that play a crucial role in activating innate immune response in brown-marbled grouper (Epinephelus fuscoguttatus) as a control agent against various infections including vibriosis. Here, we report the molecular cloning of partial open reading frames, sequences characterization, and expression profiles of Pattern Recognition Receptors (PRRs) in brown-marbled grouper. The PRRs, namely pglyrp5, tlr5, ctlD, and ctlE in brown-marbled grouper, possess conserved domains and showed shared evolutionary relationships with other fishes, humans, mammals, birds, reptilians, amphibians, and insects. In infection experiments, up to 50% mortality was found in brown-marbled grouper fingerlings infected with Vibrio alginolyticus compared to 27% mortality infected Vibrio parahaemolyticus and 100% survival of control groups. It is also demonstrated that all four PRRs had higher expression in samples infected with V. alginolyticus compared to V. parahaemolyticus. This PRRs gene expression analysis revealed that all four PRRs expressed rapidly at 4-h post-inoculation even though the Vibrio count was only detected earliest at 12-h post-inoculation in samples. The highest expression recorded was from V. alginolyticus inoculated fish spleen with up to 73-fold change for pglyrp5 gene, followed by 14 to 38-fold expression for the same treatment in spleen, head kidney, and blood samples for other PRRs, namely tlr5, ctlD, and ctlE genes. Meanwhile less than a 10% increase in expression of all four genes was detected in spleen, head kidney, and blood samples inoculated with V. parahaemolyticus. These findings indicated that pglyrp5, tlr5, ctlD, and ctlE play important roles in the early immune response to vibriosis infected, brown-marbled grouper fingerlings.

Acute hepatopancreatic necrosis (AHPND) is a severe bacterial disease affecting farmed shrimp. Although various pathogenic bacteria associated with AHPND-affected shrimp have been described, little is known about the bacterial signatures in the stomachs and intestines when the disease occurs naturally. In this study, we characterized the microbiome of P. vannamei by high-throughput sequencing (HTS). Shrimp samples were collected from a commercial farm and divided into two groups: healthy and affected by AHPND, confirmed by PCR. Stomach and intestine samples were subjected to microbiome analysis targeting the V3-V4 region of the 16S rRNA gene. PERMANOVA analysis revealed a significant disparity in the bacterial diversity between the stomach and intestine microbiomes of these two health conditions. Our results suggest that the significant abundance of Vibrio brasiliensis and V. sinaloensis in the intestines of affected shrimp plays a role in AHPND infection. This imbalance could be mitigated by the presence of Pseudoalteromonas, Gilvimarinus, and other members of the phylum Pseudomonadota such as Cellvibrionaceae, Psychromonadaceae, and Halieaceae, which showed significant abundance in healthy intestines. This study highlights the significance of the microbial community in the differentiation of specific microbial signatures in different organs of P. vannamei. These findings offer a deeper understanding of the intricate dynamics within the shrimp microbiome under these conditions, enriching our view of AHPND progression and paving the way toward future identification of probiotics tailored for more efficient management of this disease.

Nowadays, European seabass (Dicentrarchus labrax) aquaculture is undergoing a significant expansion. Nevertheless, the aquaculture industry is plagued by vibriosis. The spatial and temporal dynamics of Vibrio harveyi were studied on a European seabass farm in northern France during seven months of 2022. Concrete specimens were suspended and water was pumped from different depths (0.3 m, 2.15 m and 4 m deep), providing insights into the biofilm and planktonic V. harveyi dynamics. The abundances of V. harveyi, in the biofilm and free-living forms, were positively correlated. The water parameters revealed seasonal fluctuations in temperature, pH, and salinity, with no significant differences observed across the water column. Quantification of V. harveyi revealed no significant differences between depths, but seasonality, with peak abundances observed in August, correlated with temperature increases. Principal component analysis identified temperature as a primary driver, but also additional parameters, such as salinity and pH. Vibriosis occurred during the sampling period, providing valuable insights into the conditions before, during, and after the outbreaks. This study underscores the importance of understanding V. harveyi behaviour in aquaculture, particularly in the context of global warming, for effective disease management and sustainable practices.

The incidence of Vibrio vulnificus infections, with high mortality rates in humans and aquatic animals, has escalated, highlighting a significant public health challenge. Currently, reliable markers to identify strains with high virulence potential are lacking, and the understanding of evolutionary drivers behind the emergence of pathogenic strains is limited. In this study, we analyzed the distribution of virulent genotypes and phenotypes to discern the infectious potential of V. vulnificus strains isolated from three distinct sources. Most isolates, traditionally classified as biotype 1, possessed the virulence-correlated gene-C type. Environmental isolates predominantly exhibited YJ-like alleles, while clinical and diseased fish isolates were significantly associated with the nanA gene and pathogenicity region XII. Hemolytic activity was primarily observed in the culture supernatants of clinical and diseased fish isolates. Genetic relationships, as determined by multiple-locus variable-number tandem repeat analysis, suggested that strains originating from the same source tended to cluster together. However, multilocus sequence typing revealed considerable genetic diversity across clusters and sources. A phylogenetic analysis using single nucleotide polymorphisms of diseased fish strains alongside publicly available genomes demonstrated a high degree of evolutionary relatedness within and across different isolation sources. Notably, our findings reveal no direct correlation between phylogenetic patterns, isolation sources, and virulence capabilities. This underscores the necessity for proactive risk management strategies to address pathogenic V. vulnificus strains emerging from environmental reservoirs.IMPORTANCEAs the global incidence of Vibrio vulnificus infections rises, impacting human health and marine aquacultures, understanding the pathogenicity of environmental strains remains critical yet underexplored. This study addresses this gap by evaluating the virulence potential and genetic relatedness of V. vulnificus strains, focusing on environmental origins. We conduct an extensive genotypic analysis and phenotypic assessment, including virulence testing in a wax moth model. Our findings aim to uncover genetic and evolutionary factors that drive pathogenic strain emergence in the environment. This research advances our ability to identify reliable virulence markers and understand the distribution of pathogenic strains, offering significant insights for public health and environmental risk management.

Antibiotics are often used to treat severe Vibrio infections, with third-generation cephalosporins and tetracyclines combined or fluoroquinolones alone being recommended by the US Centers for Disease Control and Prevention. Increases in antibiotic resistance of both environmental and clinical vibrios are of concern; however, limited longitudinal data have been generated among environmental isolates to inform how resistance patterns may be changing over time. Hence, we evaluated long-term trends in antibiotic resistance of vibrios isolated from Chesapeake Bay waters (Maryland) across two 3-year sampling periods (2009-2012 and 2019-2022). Vibrio parahaemolyticus (n = 134) and Vibrio vulnificus (n = 94) toxR-confirmed isolates were randomly selected from both sampling periods and tested for antimicrobial susceptibility against eight antibiotics using the Kirby-Bauer disk diffusion method. A high percentage (94%-96%) of V. parahaemolyticus isolates from both sampling periods were resistant to ampicillin and only 2%-6% of these isolates expressed intermediate resistance or resistance to third-generation cephalosporins, amikacin, tetracycline, and trimethoprim-sulfamethoxazole. Even lower percentages of resistant V. vulnificus isolates were observed and those were mostly recovered from 2009 to 2012, however, the presence of multiple virulence factors was observed. The frequency of multi-drug resistance was relatively low (6%-8%) but included resistance against antibiotics used to treat severe vibriosis in adults and children. All isolates were susceptible to ciprofloxacin, a fluoroquinolone, indicating its sustained efficacy as a first-line agent in the treatment of severe vibriosis. Overall, our data indicate that antibiotic resistance patterns among V. parahaemolyticus and V. vulnificus recovered from the lower Chesapeake Bay have remained relatively stable since 2009.IMPORTANCEVibrio spp. have historically been susceptible to most clinically relevant antibiotics; however, resistance and intermediate-resistance have been increasingly recorded in both environmental and clinical isolates. Our data showed that while the percentage of multi-drug resistance and resistance to antibiotics was relatively low and stable across time, some Vibrio isolates displayed resistance and intermediate resistance to antibiotics typically used to treat severe vibriosis (e.g., third-generation cephalosporins, tetracyclines, sulfamethoxazole-trimethoprim, and aminoglycosides). Also, given the high case fatality rates observed with Vibrio vulnificus infections, the presence of multiple virulence factors in the tested isolates is concerning. Nevertheless, the continued susceptibility of all tested isolates against ciprofloxacin, a fluoroquinolone, is indicative of its use as an effective first-line treatment of severe Vibrio spp. infections stemming from exposure to Chesapeake Bay waters or contaminated seafood ingestion.

This study was conducted to isolate and identify the bioactive compounds from the ethanolic extract of Syzygium cumini leaf against Vibrio species through a bioassay-guided fractionation. The ethanol extract was exposed to silica gel chromatography followed by reversed phase HPLC to isolate the most effective fraction against V. parahaemolyticus. Using further UHPLC-orbitrap-ion trap mass spectrometry, five compounds were isolated with broad-spectrum potency against a range of Vibrio species viz. V. parahaemolyticus, V. alginolyticus, V. harveyi, V. vulnificus and V. anguillarum. The IC50 values for the compounds ranged from 8 to 48 µg/mL against the most sensitive species V. vulnificus and 58 to >400 µg/mL against V. alginolyticus. The results of the toxicity tests demonstrated that the compounds were not harmful for shrimp. The study\'s findings indicate that S. cumini leaf extract may contain bioactive molecules that are able to be substituted for antibiotics to treat vibriosis in shrimp farming.

Immersion vaccination, albeit easier to administer than immunization by injection, sometimes has challenges with antigen uptake, resulting in sub-optimal protection. In this research, a new strategy to enhance antigen uptake of a heat-inactivated Vibrio harveyi vaccine in Asian seabass (Lates calcarifer) using oxygen nanobubble-enriched water (ONB) and positively charged chitosan (CS) was explored. Antigen uptake in fish gills was assessed, as was the antibody response and vaccine efficacy of four different combinations of vaccine with ONB and CS, and two control groups. Pre-mixing of ONB and CS before introducing the vaccine, referred to as (ONB + CS) + Vac, resulted in superior antigen uptake and anti-V. harveyi antibody (IgM) production in both serum and mucus compared to other formulas. The integration of an oral booster (4.22 × 108 CFU/g, at day 21-25) within a vaccine trial experiment set out to further evaluate how survival rates post exposure to V. harveyi might be improved. Antibody responses were measured over 42 days, and vaccine efficacy was assessed through an experimental challenge with V. harveyi. The expression of immune-related genes IL1β, TNFα, CD4, CD8, IgT and antibody levels were assessed at 1, 3, and 7-day(s) post challenge (dpc). The results revealed that antibody levels in the group (ONB + CS) + Vac were consistently higher than the other groups post immersion immunization and oral booster, along with elevated expression of immune-related genes after challenge with V. harveyi. Ultimately, this group demonstrated a significantly higher relative percent survival (RPS) of 63 % ± 10.5 %, showcasing the potential of the ONB-CS-Vac complex as a promising immersion vaccination strategy for enhancing antigen uptake, stimulating immunological responses, and improving survival of Asian seabass against vibriosis.

Vibrio alginolyticus is the causative agent of vibriosis, a common bacterial infection in grouper aquaculture that is associated with the development of haemorrhagic and non-haemorrhagic ulcerations on the fish. In the present study, comparative proteome analysis was performed on serum samples from Vibrio-resistant and Vibrio-susceptible grouper. Samples were analysed using high-throughput LC-MS/MS and identified 2770 unique peptides that corresponded to 344 proteins. Subsequent analysis identified 21 proteins that were significantly up-regulated in the resistant group compared to the control and the susceptible groups. Those proteins are associated with immunostimulatory effects, signalling and binding cascade, metabolism, and maintaining tissue integrity and physiological condition. Besides, potential protein biomarkers related to the immune system were identified, which could be associated with the disease-resistant phenotype. These data provide insights into the underlying immune mechanism of hybrid groupers upon Vibrio sp. infection.