Prevalence and antibiotic resistance patterns of Vibrio parahaemolyticus isolated from different types of seafood in Selangor, Malaysia

Antibiotic susceptibility of Vibrio parahaemolyticus isolated from prawns and oysters marketed in Zhanjiang, China

To evaluate the antibiotic susceptibility of Vibrio parahaemolyticus from prawns and oysters marketed in Zhanjiang, Guangdong, China. 84 strains of V. parahaemolyticus were isolated from prawns and oysters sampled from 9 major markets. The results showed that 84 V. parahaemolyticus strains had the highest rate of antibiotic resistance to oxytetracycline (69.05 %, 58/84) and the lowest rate of antibiotic resistance to enrofloxacin (1.19 %, 1/84), ciprofloxacin (4.76 %, 4/84) and norfloxacin (7.14 %, 6/84) in quinolone. Meanwhile, 96.42 % of the strains showed multiple antibiotic resistance (MAR). PCR results showed that the resistance phenotype was closely related to the antibiotic resistance genes and efflux pump genes (p < 0.01), and the efflux pump gene was the key causing MAR. The combination of antibiotics significantly eliminated multidrug resistance. In addition, efflux pump inhibitors also reduce MAR. This study may provide information on antibiotic susceptibility, antibiotic resistance and strategies for the control of V. parahaemolyticus.

Exploring extended-spectrum beta lactamase resistance in Vibrio parahaemolyticus and Vibrio cholerae within the tropical mangrove ecosystem of southwest India

Multidrug-resistant pathogenic vibrios are a crisis of concern as they cause multiple illnesses, including gastroenteritis in humans and acute hepatopancreatic necrosis in aquaculture. In the current study, we investigated the prevalence of the beta-lactamase gene CTX-M-group 1 in Vibrio spp. (Vibrio cholerae and Vibrio parahaemolyticus) from the water and sediment of urban tropical mangrove ecosystems of Kerala, southwest India. A total of 120 isolates of Vibrio spp. were tested for antibiotic susceptibility to 14 antibiotics. In water, ampicillin resistance was very high in isolates of V. cholerae (94.1%, n = 17) and V. parahaemolyticus (89.1%, n = 46). 26.9% of V. parahaemolyticus and 14.2% of V. cholerae harbored the CTX-M-group 1 gene in water samples. Compared to V. cholerae, the CTX-M-group 1 gene was exclusively hosted by V. parahaemolyticus (49%) in sediment samples. A significant difference in the prevalence of the CTX-M-group 1 gene was observed among Vibrio spp. in both water and sediment samples (p < 0.05). The results revealed the presence of multidrug-resistant and beta-lactamase harboring Vibrio spp. in mangrove ecosystems, which may have evolved as a consequence of the misuse and abuse of broad-spectrum antibiotics as prophylaxis in human health care and aquaculture.

Isolation and Biological Characteristics of a Novel Phage and Its Application to Control Vibrio Parahaemolyticus in Shellfish Meat

Vibrio parahaemolyticus is a common foodborne pathogenic bacterium. With the overuse of antibiotics, an increasing proportion of drug-resistant strains are emerging, which puts enormous pressure on public health. In this study, a V. parahaemolyticus-specific phage, VP41s3, was isolated. The head length, width, and tail length of the phage were 77.7 nm, 72.2 nm, and 17.5 nm, respectively. It remained active in the temperature range of 30-50°C and pH range of 4-11. The lytic curve of phage VP41s3 showed that the host bacteria did not grow until 11 h under phage treatment at MOI of 1000, indicating that the phage had good bacteriostatic ability. When it was added to shellfish contaminated with V. parahaemolyticus (15°C, 48 h), the number of bacteria in the experimental group was 2.11 log10 CFU/mL lower than that in the control group at 24 h. Furthermore, genomic characterization and phylogenetic analysis indicated that phage VP41s3 was a new member of the Podoviridae family. The genome contained 50 open reading frames (ORFs), in which the ORF19 (thymidine kinase) was an enzyme involved in the pyrimidine salvage pathway, which might lead to the accelerated DNA synthesis efficiency after phage entered into host cells. This study not only contributed to the improvement of phage database and the development of beneficial phage resources but also revealed the potential application of phage VP41s3 in food hygiene and safety.

Multidrug-Resistance of Vibrio Species in Bivalve Mollusks from Southern Thailand: Isolation, Identification, Pathogenicity, and Their Sensitivity toward Chitooligosaccharide-Epigallocatechin-3-Gallate Conjugate

Vibrio spp. is a Gram-negative bacteria known for its ability to cause foodborne infection in association with eating raw or undercooked seafood. The majority of these foodborne illnesses are caused by mollusks, especially bivalves. Thus, the prevalence of Vibrio spp. in blood clams (Tegillarca granosa), baby clams (Paphia undulata), and Asian green mussels (Perna viridis) from South Thailand was determined. A total of 649 Vibrio spp. isolates were subjected to pathogenicity analysis on blood agar plates, among which 21 isolates from blood clams (15 isolates), baby clams (2 isolates), and green mussels (4 isolates) showed positive β-hemolysis. Based on the biofilm formation index (BFI) of β-hemolysis-positive Vibrio strains, nine isolates exhibited a strong biofilm formation capacity, with a BFI in the range of 1.37 to 10.13. Among the 21 isolates, 6 isolates (BL18, BL82, BL84, BL85, BL90, and BL92) were tlh-positive, while trh and tdh genes were not detected in all strains. Out of 21 strains, 5 strains showed multidrug resistance (MDR) against amoxicillin/clavulanic acid, ampicillin/sulbactam, cefotaxime, cefuroxime, meropenem, and trimethoprim/sulfamethoxazole. A phylogenetic analysis of MDR Vibrio was performed based on 16s rDNA sequences using the neighbor-joining method. The five MDR isolates were identified to be Vibrio neocaledonicus (one isolate), Vibrio fluvialis (one isolate) and, Vibrio cidicii (three isolates). In addition, the antimicrobial activity of chitooligosaccharide-epigallocatechin gallate (COS-EGCG) conjugate against MDR Vibrio strains was determined. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of COS-EGCG conjugate were in the range of 64-128 µg/mL. The antimicrobial activity of the conjugate was advocated by the cell lysis of MDR Vibrio strains, as elucidated by scanning electron microscopic images. Vibrio spp. isolated from blood clams, baby clams, and Asian green mussels were highly pathogenic, exhibiting the ability to produce biofilm and being resistant to antibiotics. However, the COS-EGCG conjugate could be used as a potential antimicrobial agent for controlling Vibrio in mollusks.

Isolation, characterization, and application of bacteriophage on Vibrio parahaemolyticus biofilm to control seafood contamination

OBJECTIVE

This study intended to isolate a Vibrio-particular phage from the natural environment, analyse its characteristics and genome sequence, and investigate its reduction effect on V. parahaemolyticus biofilm as a biocontrol agent in squid and mackerel.

METHODS

Among 21 phages, phage CAU_VPP01, isolated from beach mud, was chosen for further experiments based on host range and EOP tests. When examining the reduction effect of phage CAU_VPP01 against Vibrio parahaemolyticus biofilms on surfaces (stainless steel [SS] and polyethylene terephthalate [PET]) and food surfaces (squid and mackerel).

RESULTS

The phage showed the most excellent reduction effect at a multiplicity-of-infection (MOI) 10. Three-dimensional images acquired with confocal laser scanning microscopy (CLSM) analysis were quantified using COMSTAT, which showed that biomass, average thickness, and roughness coefficient decreased when treated with the phage. Colour and texture analysis confirmed that the quality of squid and mackerel was maintained after the phage treatment. Finally, a comparison of gene expression levels determined by qRT-PCR analysis showed that the phage treatment induced a decrease in the gene expression of flaA, vp0962, andluxS, as examples.

CONCLUSION

This study indicated that Vibrio-specific phage CAU_VPP01 effectively controlled V. parahaemolyticus biofilms under various conditions and confirmed that the isolated phage could possibly be used as an effective biocontrol weapon in the seafood manufacturing industry.

Antibiotic resistance trends among Vibrio vulnificus and Vibrio parahaemolyticus isolated from the Chesapeake Bay, Maryland: a longitudinal study

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.

Antimicrobial susceptibility and genomic characterization of Vibrio parahaemolyticus isolated from aquatic foods in 15 provinces, China, 2020

Prevalent in marine, estuarine and coastal environments, Vibrio parahaemolyticus is one of the major foodborne pathogens which can cause acute gastroenteritis through consumption of contaminated food. This study encompassed antimicrobial resistance, molecular characteristics and phylogenetic relationships of 163 V. parahaemolyticus isolated from aquatic foods across 15 provinces in China. The isolates showed high resistance rates against ampicillin (90.80 %, 148/163) and cefazolin (72.39 %, 118/163). Only 5 isolates demonstrated multi-drug resistance (MDR) phenotypes. A total of 37 different antibiotic resistance genes (ARGs) in correlation with seven antimicrobial categories were identified. tet(34) and tet(35) were present in all 163 isolates. Other most prevalent ARGs were those conferring resistance to β-lactams, with prevalence rate around 18.40 % (30/163). The virulence genes tdh and trh were found in 17 (10.43 %) and 9 (5.52 %) isolates, respectively. Totally 121 sequence types (STs) were identified through whole genome analysis, among which 60 were novel. The most prevalent sequence type was ST3 (9.20 %, 15/163), which shared the same genotype profile of trh_, tdh+ and blaCARB-22+. Most of the tdh+V. parahaemolyticus isolates was clustered into a distinctive clade by the phylogenetic analysis. Our study showed that the antimicrobial resistance of V. parahaemolyticus in aquatic foods in China was moderate. However, the emerging of MDR isolates implicate strengthened monitoring is needed for the better treatment of human V. parahaemolyticus infections. High genetic diversity and virulence potential of the isolates analyzed in this study help better understanding and evaluating the risk of V. parahaemolyticus posed to public health.

Meta-Analysis and Systematic Review of Phenotypic and Genotypic Antimicrobial Resistance and Virulence Factors in Vibrio parahaemolyticus Isolated from Shrimp

This systematic review and meta-analysis investigates the prevalence of Vibrio parahaemolyticus, its virulence factors, antimicrobial resistance (AMR), and its resistance determinants in shrimp. This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, to identify and select relevant peer-reviewed articles published between January 2020 and December 2022. The search strategy involved multiple online databases, including Google Scholar, PubMed, ScienceDirect, and Scopus. The inclusion criteria focused on studies that examined V. parahaemolyticus prevalence, virulence factors, and AMR in shrimp from farms to retail outlets. A total of 32 studies were analyzed, revealing a pooled estimate prevalence of V. parahaemolyticus in shrimp at 46.0%, with significant heterogeneity observed. Subgroup analysis highlighted varying prevalence rates across continents, emphasizing the need for further investigation. Virulence factor analysis identified thermostable direct hemolysin (tdh) and tdh-related hemolysin (trh) as the most common. Phenotypic AMR analysis indicated notable resistance to glycopeptides, nitrofurans, and beta-lactams. However, the correlation between antimicrobial usage in shrimp farming and observed resistance patterns was inconclusive. Funnel plots suggested potential publication bias, indicating a need for cautious interpretation of findings. This study underscores the urgency of coordinated efforts to address AMR in V. parahaemolyticus to safeguard public health and to ensure sustainable aquaculture practices.

Genomic mining of Vibrio parahaemolyticus highlights prevalence of antimicrobial resistance genes and new genetic markers associated with AHPND and tdh + /trh + genotypes

BACKGROUND

Acute Hepatopancreatic Necrosis Disease (AHPND) causes significant mortality in shrimp aquaculture. The infection is primarily instigated by Vibrio parahaemolyticus (Vp) strains carrying a plasmid encoding the binary toxin PirAB. Yet, comprehension of supplementary virulence factors associated with this relatively recent disease remains limited. Furthermore, the same holds for gastroenteritis in humans caused by other Vp genotypes. Additionally, given the prevalent use of antibiotics to combat bacterial infections, it becomes imperative to illuminate the presence of antimicrobial resistance genes within these bacteria.

RESULTS

A subsampled number of 1,036 Vp genomes was screened for the presence of antimicrobial resistance genes, revealing an average prevalence of 5 ± 2 (SD) genes. Additional phenotypic antimicrobial susceptibility testing of three Vp strains (M0904, TW01, and PV1) sequenced in this study demonstrated resistance to ampicillin by all tested strains. Additionally, Vp M0904 showed multidrug resistance (against ampicillin, tetracycline, and trimethoprim-sulfamethoxazole). With a focus on AHPND, a screening of all Vibrio spp. for the presence of pirA and/or pirB indicates an estimated prevalence of 0.6%, including four V. campbellii, four V. owensii, and a Vibrio sp. next to Vp. Their pirAB-encoding plasmids exhibited a highly conserved backbone, with variations primarily in the region of the Tn3 family transposase. Furthermore, an assessment of the subsampled Vp genomes for the presence of known virulence factors showed a correlation between the presence of the Type 3 Secretion System 2 and tdh, while the presence of the Type 6 Secretion System 1 was clade dependent. Furthermore, a genome-wide association study (GWAS) unveiled (new) genes associated with pirA, pirB, tdh, and trh genotypes. Notable associations with the pirAB genotype included outer membrane proteins, immunoglobulin-like domain containing proteins, and toxin-antitoxin systems. For the tdh + /trh + genotypes (containing tdh, trh, or both genes), associations were found with T3SS2 genes, urease-related genes and nickel-transport system genes, and genes involved in a 'minimal' type I-F CRISPR mechanism.

CONCLUSIONS

This study highlights the prevalence of antimicrobial resistance and virulence genes in Vp, identifying novel genetic markers associated with AHPND and tdh + /trh + genotypes. These findings contribute valuable insights into the genomic basis of these genotypes, with implications for shrimp aquaculture and food safety.

Prevalence, multidrug resistance, and biofilm formation of Vibrio parahaemolyticus isolated from fish mariculture environments in Cat Ba Island, Vietnam

BACKGROUND

Vibrio parahaemolyticus is a major foodborne pathogen in aquatic animals and a threat to human health worldwide. This study investigated the prevalence, antimicrobial resistance, antimicrobial resistance genes (ARGs), and biofilm formation of V. parahaemolyticus strains isolated from fish mariculture environments in Cat Ba Island, Vietnam.

METHODS

In total, 150 rearing water samples were collected from 10 fish mariculture farms in winter and summer. A polymerase chain reaction assay was used to identify V. parahaemolyticus, its virulence factors, and ARGs. The antimicrobial resistance patterns and biofilm formation ability of V. parahaemolyticus strains were investigated using the disk diffusion test and a microtiter plate-based crystal violet method, respectively.

RESULTS

Thirty-seven V. parahaemolyticus isolates were recovered from 150 samples. The frequencies of the tdh and trh genes among V. parahaemolyticus isolates were 8.1% and 21.6%, respectively. More than 90% of isolates were susceptible to ceftazidime, cefotaxime, and chloramphenicol, but over 72% were resistant to ampicillin, tetracycline, and erythromycin. Furthermore, 67.57% of isolates exhibited multidrug resistance. The presence of ARGs related to gentamicin (aac(3)-IV), tetracycline (tetA) and ciprofloxacin (qnrA) in V. parahaemolyticus isolates was identified. Conversely, no ARGs related to ampicillin or erythromycin resistance were detected. Biofilm formation capacity was detected in significantly more multidrug-resistant isolates (64.9%) than non-multidrug-resistant isolates (18.9%).

CONCLUSION

Mariculture environments are a potential source of antibiotic-resistant V. parahaemolyticus and a hotspot for virulence genes and ARGs diffusing to aquatic environments. Thus, the prevention of antibiotic-resistant foodborne vibriosis in aquatic animals and humans requires continuous monitoring.

Prevalence, virulence characteristics, and antimicrobial resistance of Vibrio parahaemolyticus isolates from raw seafood in a province in Northern Thailand

Vibrio parahaemolyticus (V. parahaemolyticus) is commonly found in seawater and seafood products, but evidence is limited of its presence in seafood marketed in locations very distant from coastal sources. This study determined the prevalence and characterization of V. parahaemolyticus in seafood from markets in landlocked Phayao province, Northern Thailand. Among 120 samples, 26 (21.7%) were positive for V. parahaemolyticus, being highest in shrimp (43.3%), followed by shellfish (36.7%), and squid (6.7%), but was not found in fish. V. parahaemolyticus comprised 33 isolates that were non-pathogenic and non-pandemic. Almost all isolates from shrimp and shellfish samples were positive for T3SS1. Only five isolates (15.2%) showed two antimicrobial resistance patterns, namely, kanamycin-streptomycin (1) carrying sul2 and ampicillin-kanamycin-streptomycin (4) that carried tetA (2), tetA-sul2 (1), as well as one negative. Antimicrobial susceptible V. parahaemolyticus isolates possessing tetA (67.9%) and sul2 (3.5%) were also found. Six isolates positive for integron class 1 and/or class 2 were detected in 4 antimicrobial susceptible and 2 resistant isolates. While pathogenic V. parahaemolyticus was not detected, contamination of antimicrobial resistance V. parahaemolyticus in seafood in locations distant from coastal areas requires ongoing monitoring to improve food safety in the seafood supply chain.

Bovine Lactoferrin and Hen Ovotransferrin Affect Virulence Factors of Acute Hepatopancreatic Necrosis Disease (AHPND)-Inducing Vibrio parahaemolyticus Strains

Acute Hepatopancreatic Necrosis Disease (AHPND), a highly destructive shrimp disease, has inflicted severe setbacks on the shrimp farming industry worldwide. As the use of antibiotics is discouraged due to emerging antibiotic-resistant bacteria and the pollution of ecosystems, there is a pressing demand for novel, sustainable alternatives. Hence, the influence of bovine lactoferrin (bLF) and hen ovotransferrin (OT), two natural antimicrobial proteins, on the growth of three AHPND-causing Vibrio parahaemolyticus (Vp) strains (M0904, TW01 and PV1) was examined. Additionally, we explored their potential to affect selected Vp virulence factors such as biofilm formation, swimming and swarming, cell surface hydrophobicity, and activity of released lipases and caseinases. Lag phases of all bacterial growth curves were significantly prolonged in the presence of bLF or OT (1, 5 and 10 mg/mL), and bLF (5 and 10 mg/mL) completely inhibited growth of all strains. In addition, bLF or OT significantly reduced biofilm formation (all tested bLF and OT concentrations for Vp M0904 and Vp PV1), bacterial swimming motility (0.5 mg/mL bLF and OT for Vp M0904 and Vp TW01; 1 mg/mL bLF and OT for all strains), cell surface hydrophobicity (for all strains, all bLF and OT concentrations tested except for 0.125 mg/mL OT for Vp PV1) and lipase activity (1 mg/mL bLF and OT for all strains and 0.5 mg/mL bLF and OT for Vp PV1). These promising in vitro results suggest that bLF and/or OT might be used as novel agents for combating AHPND and warrant further research to elucidate the underlying mechanisms of action to fully unlock their potential for AHPND disease management.

Antimicrobial Resistant Bacteria Monitoring in Raw Seafood Retailed: a Pilot Study Focused on Vibrio and Aeromonas

In aquaculture, bacterial infections in sea animals are treated using antimicrobials. As seafood is frequently consumed in its raw form, seafood contaminated with water-borne antimicrobial-resistant bacteria presents a potential transmission route to humans and can influence food safety. In this study, we aimed to determine the abundance of water-borne bacteria in retail raw seafood and to characterize their antimicrobial resistance profiles. In total, 85 retail raw seafood samples (32 fish, 26 shellfish, 25 mollusks, and two crustaceans) were purchased from supermarkets in Japan, and water-borne bacteria were isolated. The isolated bacterial species predominantly included Vibrio spp. (54.1%) and Aeromonas spp. (34.1%). Vibrio or Aeromonas spp. were isolated from more than 70% of the seafood samples. Tetracycline-, sulfamethoxazole-, and/or trimethoprim/sulfamethoxazole-resistant Vibrio or Aeromonas spp. isolates were detected in seven (21.9%) fish samples (two wild-caught and five farm-raised) harboring tet, sul, and/or dfr genes. Sulfamethoxazole- and trimethoprim/sulfamethoxazole-resistant isolates were only detected in farm-raised fish. Tetracycline and sulfamethoxazole are commonly used in aquaculture. These results suggest that water-borne bacteria like Vibrio and Aeromonas spp. should be the primary focus of antimicrobial-resistant bacteria monitoring to effectively elucidate their spread of bacteria via seafood.

Dynamics of efflux pumps in antimicrobial resistance, persistence, and community living of Vibrionaceae

The marine bacteria of the Vibrionaceae family are significant from the point of view of their role in the marine geochemical cycle, as well as symbionts and opportunistic pathogens of aquatic animals and humans. The well-known pathogens of this group, Vibrio cholerae, V. parahaemolyticus, and V. vulnificus, are responsible for significant morbidity and mortality associated with a range of infections from gastroenteritis to bacteremia acquired through the consumption of raw or undercooked seafood and exposure to seawater containing these pathogens. Although generally regarded as susceptible to commonly employed antibiotics, the antimicrobial resistance of Vibrio spp. has been on the rise in the last two decades, which has raised concern about future infections by these bacteria becoming increasingly challenging to treat. Diverse mechanisms of antimicrobial resistance have been discovered in pathogenic vibrios, the most important being the membrane efflux pumps, which contribute to antimicrobial resistance and their virulence, environmental fitness, and persistence through biofilm formation and quorum sensing. In this review, we discuss the evolution of antimicrobial resistance in pathogenic vibrios and some of the well-characterized efflux pumps' contributions to the physiology of antimicrobial resistance, host and environment survival, and their pathogenicity.

Distinct increase in antimicrobial resistance genes among Vibrio parahaemolyticus in recent decades worldwide

Vibrio parahaemolyticus is a common pathogen, and has emerged with multiple antimicrobial resistance (AMR). However, few studies have conducted large-scale investigations of AMR and virulence trends of V. parahaemolyticus worldwide. This study longitudinally monitored antibiotic resistance genes (ARGs) and virulence factor genes (VFGs) trends of 1540 V. parahaemolyticus isolates isolated from 1951 to 2021. The number of ARGs in V. parahaemolyticus isolates distinctly increased over the years (P = 5.9e-10), while the number of VFGs decreased significantly (P < 2.2e-16). However, the number of VFGs of isolates isolated from humans has not changed significantly over the years (R = 0.013, P = 0.74), suggesting that the pathogenic risk to humans has not been reduced. Besides, mobile genetic elements are important contributors to ARGs in V. parahaemolyticus (R = 0.34, P < 2.2e-16), but have no promoting effect on VFGs (P = 0.50). The structural equation model illustrated that the human development index promoted the consumption of antibiotics, thereby indirectly promoting an increase in the AMR of the V. parahaemolyticus isolates. Finally, the random forest was performed to predict the ARG and VFG risks of global terrestrial V. parahaemolyticus isolates, and successfully map these threats with over 80% accuracy. This study aimed to evaluate the global risks posed by AMR and virulence, which helps to develop methods specifically targeting V. parahaemolyticus to mitigate these threats.

Distribution and antibiotic resistance of vibrio population in an urbanized tropical lake-the Vembanad-in the southwest coast of India

Among the diverse Vibrio spp. autochthonous to coastal ecosystems, V. cholerae, V. fluvialis, V. vulnificus and V. parahaemolyticus are pathogenic to humans. Increasing sea-surface temperature, sea-level rise and water-related disasters associated with climate change have been shown to influence the proliferation of these bacteria and change their geographic distribution. We investigated the spatio-temporal distribution of Vibrio spp. in a tropical lake for 1 year at a 20-day interval. The abundance of Vibrio spp. was much higher during the south-west monsoon in 2018, when the lake experienced a once-in-a-century flood. The distribution of Vibrio spp. was influenced by salinity (r = 0.3, p < 0.001), phosphate (r = 0.18, p < 0.01) and nitrite (r = 0.16, p < 0.02) in the water. We isolated 470 colonies of Vibrio-like organisms and 341 could be revived further and identified using 16S rRNA gene sequencing. Functional annotations showed that all the 16 Vibrio spp. found in the lake could grow in association with animals. More than 60% of the isolates had multiple antibiotic resistance (MAR) index greater than 0.5. All isolates were resistant to erythromycin and cefepime. The proliferation of multiple antibiotic-resistant Vibrio spp. is a threat to human health. Our observations suggest that the presence of a diverse range of Vibrio spp. is favoured by the low-saline conditions brought about by heavy precipitation. Furthermore, infections caused by contact with Vibrio-contaminated waters may be difficult to cure due to their multiple antibiotic resistances. Therefore, continuous monitoring of bacterial pollution in the lakes is essential, as is the generation of risk maps of vibrio-infested waters to avoid public contact with contaminated waters and associated disease outbreaks.

Antimicrobial resistance and antagonistic features of bivalve-associated Vibrio parahaemolyticus from the south-west coast of India

Vibrio parahaemolyticus, a potent human and aquatic pathogen, is usually found in estuaries and oceans. Human illness is associated with consuming uncooked/partially cooked contaminated seafood. The study on bivalve-associated V. parahaemolyticus revealed that the post-monsoon season had the highest bacterial abundance (9 ± 1.5 log cfu) compared to the monsoon season (8.03 ± 0.56 log cfu). Antimicrobial resistance (AMR) profiling was performed on 114 V. parahaemolyticus isolates obtained from bivalves. The highest AMR was observed against ampicillin (78%). Chloramphenicol was found to be effective against all the isolates. Multiple antibiotic resistance index values of 0.2 or higher were detected in 18% of the isolates. Molecular analysis of antimicrobial resistant genes (ARGs) revealed the high prevalence (100%) of the TEM-1 gene in the aquatic environment. After plasmid profiling and curing, 41.6% and 100% of the resistant isolates were found to be sensitive to ampicillin and cephalosporins, respectively, indicating the prevalence of plasmid-associated ARGs in the aquatic environment. A study to evaluate the antagonistic properties of Bacillus subtilis, Pseudomonas aeruginosa, and Bacillus amyloliquefaciens against V. parahaemolyticus isolates identified the potential of these bacteria to resist the growth of V. parahaemolyticus.

Comparative genomic analysis reveals the potential transmission of Vibrio parahaemolyticus from freshwater food to humans

Vibrio parahaemolyticus is an increasingly important foodborne pathogen that cause acute gastroenteritis in humans. However, the prevalence and transmission of this pathogen in freshwater food remains unclear. This study aimed to determine the molecular characteristics and genetic relatedness of V. parahaemolyticus isolates obtained from freshwater food, seafood, environmental, and clinical samples. A total of 138 (46.6%) isolates were detected from 296 food and environmental samples, and 68 clinical isolates from patients. Notably, V. parahaemolyticus was more prevalent in freshwater food (56.7%, 85/150) than in seafood (38.8%, 49/137). Virulence phenotype analyses revealed that the high motility of isolates from freshwater food (40.0%) and clinical isolates (42.0%) was higher than that of isolates from seafood (12.2%), whereas the biofilm-forming capacity of freshwater food isolates (9.4%) was lower than that of seafood (22.4%) and clinical isolates (15.9%). Virulence genes analysis showed that 46.4% of the clinical isolates contained the tdh gene encoding thermostable direct hemolysin (TDH) and only two freshwater food isolates contained the trh gene encoding TDH-related hemolysin (TRH). Multilocus sequence typing (MLST) analysis divided the 206 isolates into 105 sequence types (STs), including 56 (53.3%) novel STs. ST2583, ST469, and ST453 have been isolated from freshwater food and clinical samples. Whole-genome sequence (WGS) analyses revealed that the 206 isolates were divided into five clusters. Cluster II contained isolates from freshwater food and clinical samples, whereas the other clusters contained isolates from seafood, freshwater food, and clinical samples. In addition, we observed that ST2516 had the same virulence pattern, with a close phylogenetic relationship to ST3. The increased prevalence and adaption of V. parahaemolyticus in freshwater food is a potential cause of clinical cases closely related to the consumption of V. parahaemolyticus contaminated freshwater food.

Antibiotic Resistance in Selected Emerging Bacterial Foodborne Pathogens-An Issue of Concern?

Antibiotic resistance (AR) and multidrug resistance (MDR) have been confirmed for all major foodborne pathogens: Campylobacter spp., Salmonella spp., Escherichia coli and Listeria monocytogenes. Of great concern to scientists and physicians are also reports of antibiotic-resistant emerging food pathogens-microorganisms that have not previously been linked to food contamination or were considered epidemiologically insignificant. Since the properties of foodborne pathogens are not always sufficiently recognized, the consequences of the infections are often not easily predictable, and the control of their activity is difficult. The bacteria most commonly identified as emerging foodborne pathogens include Aliarcobacter spp., Aeromonas spp., Cronobacter spp., Vibrio spp., Clostridioides difficile, Escherichia coli, Mycobacterium paratuberculosis, Salmonella enterica, Streptocccus suis, Campylobacter jejuni, Helicobacter pylori, Listeria monocytogenes and Yersinia enterocolitica. The results of our analysis confirm antibiotic resistance and multidrug resistance among the mentioned species. Among the antibiotics whose effectiveness is steadily declining due to expanding resistance among bacteria isolated from food are β-lactams, sulfonamides, tetracyclines and fluoroquinolones. Continuous and thorough monitoring of strains isolated from food is necessary to characterize the existing mechanisms of resistance. In our opinion, this review shows the scale of the problem of microbes related to health, which should not be underestimated.

Effects of dietary Scutellaria baicalensis extract on growth performance, immune-related genes expression, and resistance against Vibrio parahaemolyticus in white shrimp (Litopenaeus vannamei)

In this study dietary Scutellaria baicalensis extract (SBE) was used to improve the shrimps' immune response and its resistance to Vibrio parahaemolyticus. SBE obtained by solid-liquid extraction (SLE) has shown stronger antibacterial activity against V. parahaemolyticus compared to extracts obtained through the pressurized liquid extraction (PLE) method. A stronger immune response, such as the production of reactive oxygen species and the induction of expression of immune genes in hemocytes was seen in the SBE (SLE) treated group in vitro. SBE (SLE) had better immune stimulation effects and bactericidal activity than SBE (PLE) and therefore was chosen for in vivo feeding trial. The group fed with 1% SBE showed a better growth performance after 2 weeks of the feeding trial, but the growth-promoting effects did not last until the end of the trial at week four. Higher SBE intake reduced shrimp resistance to V. parahaemolyticus on week two but showed better resistance than the control group on the fourth week. Gene expression assays were used to investigate contradictory responses of the SBE-fed groups to V. parahaemolyticus at different times. Most of the genes examined in the selected tissues were not significantly changed, suggesting that the higher mortality of shrimp fed with high dose of SBE was not due to suppression of immune-related genes at earlier time point. Collectively, the bioactivity of SBE is influenced by the extraction conditions. Higher dietary doses of SBE (1% and 5%) improved the resistance of the white shrimp to V. parahaemolyticus after a longer feeding period (week four), but caution should be taken when applying SBE in the feed since a vulnerable status (week two) was seen during the feeding trial.

Repeated cross-sectional study identifies differing risk factors associated with microbial contamination in common food products in the United Kingdom

All foods carry microbes, many of which are harmless, but foods can also carry pathogens and/or microbial indicators of contamination. Limited information exists on the co-occurrence of microbes of food safety concern and the factors associated with their presence. Here, a population-based repeated cross-sectional design was used to determine the prevalence and co-occurrence of Escherichia coli, Klebsiella spp., Salmonella spp. and Vibrio spp. in key food commodities - chicken, pork, prawns, salmon and leafy greens. Prevalence in 1,369 food samples for these four target bacterial genera/species varied, while 25.6% of all samples had at least two of the target bacteria and eight different combinations of bacteria were observed as co-occurrence profiles in raw prawns. Imported frozen chicken was 6.4 times more likely to contain Salmonella than domestic chicken, and imported salmon was 5.5 times more likely to be contaminated with E. coli. Seasonality was significantly associated with E. coli and Klebsiella spp. contamination in leafy greens, with higher detection in summer and autumn. Moreover, the odds of Klebsiella spp. contamination were higher in summer in chicken and pork samples. These results provide insight on the bacterial species present on foods at retail, and identify factors associated with the presence of individual bacteria, which are highly relevant for food safety risk assessments and the design of surveillance programmes.

Isolation and characterization of a novel phage belonging to a new genus against Vibrio parahaemolyticus

BACKGROUND

Vibrio parahaemolyticus is a major foodborne pathogen that contaminates aquatic products and causes great economic losses to aquaculture. Because of the emergence of multidrug-resistant V. parahaemolyticus strains, bacteriophages are considered promising agents for their biocontrol as an alternative or supplement to antibiotics. In this study, a lytic vibriophage, vB_VpaM_R16F (R16F), infecting V. parahaemolyticus 1.1997^T was isolated, characterized and evaluated for its biocontrol potential.

METHODS

A vibriophage R16F was isolated from sewage from a seafood market with the double-layer agar method. R16F was studied by transmission electron microscopy, host range, sensitivity of phage particles to chloroform, one-step growth curve and lytic activity. The phage genome was sequenced and in-depth characterized, including phylogenetic and taxonomic analysis.

RESULTS

R16F belongs to the myovirus morphotype and infects V. parahaemolyticus, but not nine other Vibrio spp. As characterized by determining its host range, one-step growth curve, and lytic activity, phage R16F was found to highly effective in lysing host cells with a short latent period (< 10 min) and a small burst size (13 plaque-forming units). R16F has a linear double-stranded DNA with genome size 139,011 bp and a G + C content of 35.21%. Phylogenetic and intergenomic nucleotide sequence similarity analysis revealed that R16F is distinct from currently known vibriophages and belongs to a novel genus. Several genes (e.g., encoding ultraviolet damage endonuclease and endolysin) that may enhance environmental competitiveness were found in the genome of R16F, while no antibiotic resistance- or virulence factor-related gene was detected.

CONCLUSIONS

In consideration of its biological and genetic properties, this newly discovered phage R16F belongs to a novel genus and may be a potential alternate biocontrol agent.

Prevalence of Antibiotic-Resistant Seafood-Borne Pathogens in Retail Seafood Sold in Malaysia: A Systematic Review and Meta-Analysis

The objective of this study was to examine the frequency and extent of antibiotic-resistant pathogens in seafood sold in Malaysia, using a systematic review and meta-analysis approach to analyze primary research studies. Four bibliographic databases were systematically searched for primary studies on occurrence. Meta-analysis using a random-effect model was used to understand the prevalence of antibiotic-resistant bacteria in retail seafood sold in Malaysia. A total of 1938 primary studies were initially identified, among which 13 met the inclusion criteria. In the included primary studies, a total of 2281 seafoods were analyzed for the presence of antibiotic-resistant seafood-borne pathogens. It was observed that 51% (1168/2281) of the seafood was contaminated with pathogens. Overall, the prevalence of antibiotic-resistant seafood-borne pathogens in retail seafood was 55.7% (95% CI: 0.46-0.65). Antibiotic-resistant Salmonella species had an overall prevalence of 59.9% (95% CI: 0.32-0.82) in fish, Vibrio species had an overall prevalence of 67.2% (95% CI: 0.22-0.94) in cephalopods, and MRSA had an overall prevalence of 70.9% (95% CI: 0.36-0.92) in mollusks. It could be concluded that there is a high prevalence of antibiotic-resistant seafood-borne pathogens in the retail seafood sold in Malaysia, which could be of public health importance. Therefore, there is a need for proactive steps to be taken by all stakeholders to reduce the widespread transmission of antibiotic-resistant pathogens from seafood to humans.

Incidence, virulence genes and antimicrobial resistance of Vibrio parahaemolyticus isolated from seafood

The objective of the study was to establish the incidence, pathogenic factors and antimicrobial resistance of Vibrio parahaemolyticus in seafood from retail shops in Bulgaria. A hundred and eighty samples of sea fish, mussels, oysters, veined rapa whelks, shrimps and squids were included in the study. PCR methods were used to identify V. parahaemolyticus and prove tdh and trh genes. Antimicrobial resistance was established by disc diffusion method, and MAR index was calculated. The results proved the presence of V. parahaemolyticus in 24% (44/180) of the seafood samples. tdh-positive V. parahaemolyticus was not found, while the trh gene was detected in one veined rapa whelk isolate. All isolates were susceptible to Sulfamethoxazole/trimethoprim, Tetracycline, Gentamycin, Amoxicillin-clavulanic acid, Amikacin, Ciprofloxacin, and Levofloxacin. Intermediate resistance was found to Ampicillin (25%; 11/44), Cefepime (16%; 7/44), and Ceftazidime (2%; 1/44). The results showed that 16% (7/44) of the isolates were resistant to Cefepime, 9% (4/44) to Ampicillin, and 5% (2/44) to Ceftazidime. MAR-index values ranged from 0.10 to 0.30. The incidence of pathogenic and multidrug-resistant V. parahaemolyticus strains in seafood offered on the market poses a risk to consumer health.

The Influence of Outer Membrane Protein on Ampicillin Resistance of Vibrio parahaemolyticus

The antibiotic resistance of the food-borne pathogen Vibrio parahaemolyticus has attracted researchers' attention in recent years, but its molecular mechanism remains poorly understood. In this study, 7 genes encoding outer membrane proteins (OMPs) were individually deleted in V. parahaemolyticus ATCC33846, and the resistance of these 7 mutants to 14 antibiotics was investigated. The results revealed that the resistance of the 7 mutants to ampicillin was significantly increased. Further exploration of 20-gene transcription changes by real time-qPCR (RT-qPCR) demonstrated that the higher ampicillin resistance might be attributed to the expression of β-lactamase and reduced peptidoglycan (PG) synthesis activity through reduced transcription of penicillin-binding proteins (PBPs), increased transcription of l,d-transpeptidases, downregulated d,d-carboxypeptidase, and alanine deficiency. This study provides a new perspective on ampicillin resistance in OMP mutants with respect to PG synthesis.

Chicken Enterococcus faecalis-induced immunoglobulin Y as a prophylactic and therapeutic agent against streptococcosis in red tilapia (Oreochromis hybrid)

Background and Aim

Streptococcosis is a common bacterial disease in red tilapia, in which Enterococcus faecalis infection has not been widely reported. This study aimed to evaluate the efficacy of pellets that contain chicken E. faecalis-induced immunoglobulin Y (IgY) to treat and prevent streptococcosis in red tilapia.

Materials and Methods

We conducted a 28-day study for immunoprophylaxis and immunotherapy, each using four groups with two replications: Healthy control fish (KS), non-IgY pellets (PA and TA), pellets with 25% egg yolk containing E. faecalis-induced IgY (PB and TB), and pellets with 50% egg yolk containing E. faecalis-induced IgY(PC and TC). Indirect enzyme-linked immunosorbent assay was performed on prototype pellets produced with an IgY suspension at 1.63 mg/mL as the standard optical density curve. For the immunoprophylaxis study, pellets of 3% of the average body weight of the experimental fish (0.50 g per fish per day) were given daily until day 14 before the challenge test with E. faecalis (2.1 × 10⁹ Colony-forming unit/mL peroral) on day 15. The data from the observation period on days 15-28 were analyzed. For the immunotherapy study, pellets of 3% of the average body weight (0.50 g per fish per day) were given daily for 21 days (days 8-28) 7 day spost-infection. The data from the immunotherapy study were collected during the observation period on days 8-28. Statistical analysis was performed on non-specific immune variables: Total leukocytes, monocytes, lymphocytes, neutrophils, phagocytic activity, and macrophage capacity; and the semi-quantitative distribution of melanomacrophage centers (MMCs) in the lymphoid organs, such as spleen and liver. Photomacrographic data were analyzed descriptively and qualitatively by comparing the healing process and clinical signs found between experiments in the immunotherapy study.

Results

The pellet with 50% egg yolk with an IgY at 2.43 mg/g pellet, 3% of body weight once daily, was the best formula on experimental fish. The administration of this formulation can also increase non-specific immunity and the distribution of MMCs in the spleen and liver with a survival rate of 55% for 14 days of challenge period in the immunoprophylaxis study and 70% for 21 days of therapy period in the immunotherapy study.

Conclusion

Immunoglobulin Y can be a prophylactic and therapeutic agent against streptococcal infections caused E. faecalis in red tilapia with an optimum dosage of 2.43 mg/g pellet.

Incidence, genetic diversity, and antimicrobial resistance profiles of Vibrio parahaemolyticus in seafood in Bangkok and eastern Thailand

Background

Emergence of Vibrio parahaemolyticus pandemic strain O3:K6 was first documented in 1996. Since then it has been accounted for large outbreaks of diarrhea globally. In Thailand, prior studies on pandemic and non-pandemic V. parahaemolyticus had mostly been done in the south. The incidence and molecular characterization of pandemic and non-pandemic strains in other parts of Thailand have not been fully characterized. This study examined the incidence of V. parahaemolyticus in seafood samples purchased in Bangkok and collected in eastern Thailand and characterized V. parahaemolyticus isolates. Potential virulence genes, VPaI-7, T3SS2, and biofilm were examined. Antimicrobial resistance (AMR) profiles and AMR genes (ARGs) were determined.

Methods

V. parahaemolyticus was isolated from 190 marketed and farmed seafood samples by a culture method and confirmed by polymerase chain reaction (PCR). The incidence of pandemic and non-pandemic V. parahaemolyticus and VPaI-7, T3SS2, and biofilm genes was examined by PCR. AMR profiles were verified by a broth microdilution technique. The presence of ARGs was verified by genome analysis. V. parahaemolyticus characterization was done by multilocus sequence typing (MLST). A phylogenomic tree was built from nucleotide sequences by UBCG2.0 and RAxML softwares.

Results

All 50 V. parahaemolyticus isolates including 21 pathogenic and 29 non-pathogenic strains from 190 samples had the toxRS/old sequence, indicating non-pandemic strains. All isolates had biofilm genes (VP0950, VP0952, and VP0962). None carried T3SS2 genes (VP1346 and VP1367), while VPaI-7 gene (VP1321) was seen in two isolates. Antimicrobial susceptibility profiles obtained from 36 V. parahaemolyticus isolates revealed high frequency of resistance to colistin (100%, 36/36) and ampicillin (83%, 30/36), but susceptibility to amoxicillin/clavulanic acid and piperacillin/tazobactam (100%, 36/36). Multidrug resistance (MDR) was seen in 11 isolates (31%, 11/36). Genome analysis revealed ARGs including blaCARB (100%, 36/36), tet(34) (83%, 30/36), tet(35) (42%, 15/36), qnrC (6%, 2/36), dfrA6 (3%, 1/36), and blaCTX-M-55 (3%, 1/36). Phylogenomic and MLST analyses classified 36 V. parahaemolyticus isolates into 5 clades, with 12 known and 13 novel sequence types (STs), suggesting high genetic variation among the isolates.

Conclusions

Although none V. parahaemolyticus strains isolated from seafood samples purchased in Bangkok and collected in eastern Thailand were pandemic strains, around one third of isolates were MDR V. parahaemolyticus strains. The presence of resistance genes of the first-line antibiotics for V. parahaemolyticus infection raises a major concern for clinical treatment outcome since these resistance genes could be highly expressed under suitable circumstances.

Serological and Antibiotic Resistance Patterns As Well As Molecular Characterization of Vibrio parahaemolyticus Isolated from Coastal Waters in the Eastern Province of Saudi Arabia

Vibrio parahaemolyticus belongs to the halophilic genus of Vibrionaceae family that inhabits coastal and marine environments and is a major food-borne pathogen. In the Gulf Cooperation Council (GCC) countries and Saudi Arabia in particular, there is a lack of information regarding the detection of pandemic clone or serovariants of V. parahaemolyticus pandemic clones. Here, 400 seawater samples were collected and examined for the presence of V. parahaemolyticus from 10 locations along the coast of Eastern Province in Saudi Arabia. The recovered isolates were serotyped, and studied for antimicrobial resistance, virulence genes, and markers of pandemicity using PCR and Arbitrarily primed (AP)-PCR typing patterns. All 40 isolates were tested negative for tdh, trh, and toxRS genes. Six serotypes were identified and three were clinically significant. Antibiotic susceptibility testing of isolates revealed high resistance towards penicillins, cephalosporins, and polymyxin; 60% of isolates were multi-drug resistant, whereas all isolates were susceptible to quinolones, carbapenems, sulfonamides, and tetracycline. The multiple antibiotic resistance (MAR) index among antibiotic resistance patterns of isolates revealed that 12 (30%) isolates had recorded significant MAR index higher than 0.2. AP-PCR fingerprinting could group all isolates into five distinct and identical pattern clusters with more than 85% similarity. Our findings demonstrate that pandemic serovariants of pandemic clones were not exclusively limited to strains isolated from fecal specimens of infected patients. Nine environmental strains of serotype O1:KUT, O1: K25, and O5:K17 were isolated from costal seawater, and thus the spread of these serovariants strains of pandemic clone of V. parahaemolyticus in the environment is to avoid any kind of threat to public health.

Antibiofilm Efficacy of Quercetin against Vibrio parahaemolyticus Biofilm on Food-Contact Surfaces in the Food Industry

Vibrio parahaemolyticus, one of the most common foodborne pathogenic bacteria that forms biofilms, is a persistent source of concern for the food industry. The food production chain employs a variety of methods to control biofilms, although none are completely successful. This study aims to evaluate the effectiveness of quercetin as a food additive in reducing V. parahaemolyticus biofilm formation on stainless-steel coupons (SS) and hand gloves (HG) as well as testing its antimicrobial activities. With a minimum inhibitory concentration (MIC) of 220 µg/mL, the tested quercetin exhibited the lowest bactericidal action without visible growth. In contrast, during various experiments in this work, the inhibitory efficacy of quercetin at sub-MICs levels (1/2, 1/4, and 1/8 MIC) against V. parahaemolyticus was examined. Control group was not added with quercetin. With increasing quercetin concentration, swarming and swimming motility, biofilm formation, and expression levels of target genes linked to flagellar motility (flaA, flgL), biofilm formation (vp0952, vp0962), virulence (VopQ, vp0450), and quorum-sensing (aphA, luxS) were all dramatically suppressed. Quercetin (0−110 μg/mL) was investigated on SS and HG surfaces, the inhibitory effect were 0.10−2.17 and 0.26−2.31 log CFU/cm2, respectively (p < 0.05). Field emission scanning electron microscopy (FE-SEM) corroborated the findings because quercetin prevented the development of biofilms by severing cell-to-cell contacts and inducing cell lysis, which resulted in the loss of normal cell shape. Additionally, there was a significant difference between the treated and control groups in terms of motility (swimming and swarming). According to our research, quercetin produced from plants should be employed as an antibiofilm agent in the food sector to prevent the growth of V. parahaemolyticus biofilms. These results indicate that throughout the entire food production chain, bacterial targets are of interest for biofilm reduction with alternative natural food agents in the seafood industry.

Diagnosis, Management, and Future Control of Cholera

Cholera, caused by Vibrio cholerae, persists in developing countries due to inadequate access to safe water, sanitation, and hygiene. There are approximately 4 million cases and 143,000 deaths each year due to cholera. The disease is transmitted fecally-orally via contaminated food or water. Severe dehydrating cholera can progress to hypovolemic shock due to the rapid loss of fluids and electrolytes, which requires a rapid infusion of intravenous (i.v.) fluids. The case fatality rate exceeds 50% without proper clinical management but can be less than 1% with prompt rehydration and antibiotics. Oral cholera vaccines (OCVs) serve as a major component of an integrated control package during outbreaks or within zones of endemicity. Water, sanitation, and hygiene (WaSH); health education; and prophylactic antibiotic treatment are additional components of the prevention and control of cholera. The World Health Organization (WHO) and the Global Task Force for Cholera Control (GTFCC) have set an ambitious goal of eliminating cholera by 2030 in high-risk areas.

Antimicrobial Efficacy of Quercetin against Vibrio parahaemolyticus Biofilm on Food Surfaces and Downregulation of Virulence Genes

For the seafood industry, Vibrio parahaemolyticus, one of the most prevalent food-borne pathogenic bacteria that forms biofilms, is a constant cause of concern. There are numerous techniques used throughout the food supply chain to manage biofilms, but none are entirely effective. Through assessing its antioxidant and antibacterial properties, quercetin will be evaluated for its ability to prevent the growth of V. parahaemolyticus biofilm on shrimp and crab shell surfaces. With a minimum inhibitory concentration (MIC) of 220 µg/mL, the tested quercetin exhibited the lowest bactericidal action without visible growth of bacteria. In contrast, during various experiments in this work, the inhibitory efficacy of quercetin without (control) and with sub-MICs levels (1/2, 1/4, and 1/8 MIC) against V. parahaemolyticus was examined. With increasing quercetin concentration, swarming and swimming motility, biofilm formation, and expression levels of related genes linked to flagella motility (flaA and flgL), biofilm formation (vp0952 and vp0962), and quorum-sensing (luxS and aphA) were all dramatically reduced (p < 0.05). Quercetin (0−110 μg/mL) was investigated on shrimp and crab shell surfaces, the inhibitory effects were 0.68−3.70 and 0.74−3.09 log CFU/cm2, respectively (p < 0.05). The findings were verified using field emission scanning electron microscopy (FE-SEM), which revealed quercetin prevented the development of biofilms by severing cell-to-cell contacts and induced cell lysis, which resulted in the loss of normal cell shape. Furthermore, there was a substantial difference in motility between the treatment and control groups (swimming and swarming). According to our findings, plant-derived quercetin should be used as an antimicrobial agent in the food industry to inhibit the establishment of V. parahaemolyticus biofilms. These findings suggest that bacterial targets are of interest for biofilm reduction with alternative natural food agents in the seafood sector along the entire food production chain.

Quantitative Risk Assessment of Vibrio parahaemolyticus in Shellfish from Retail to Consumption in Coastal Cities of Eastern China

ABSTRACT

Vibrio parahaemolyticus is the main foodborne pathogen worldwide that causes acute gastroenteritis. A quantitative microbiological risk assessment (QMRA) was conducted to evaluate the health risk associated with V. parahaemolyticus in shellfish in the coastal cities in the eastern part of the People's Republic of China. The QMRA framework was established from shellfish at retail to cooking at home to consumption. The prevalence and level of V. parahaemolyticus in shellfish, cooking methods, storage temperature, time after purchase, shellfish consumption frequency, and consumption amount were analyzed in the exposure assessment. The results of the exposure assessment were introduced into the beta-Poisson dose-response model, and Monte Carlo analysis was used to calculate the risk of gastroenteritis from shellfish consumption. The probability of illness caused by V. parahaemolyticus from shellfish consumption per person per year (Pill,yr) was 3.49E-05. Seasonal differences were noted in the Pill/meal; the maximum was 4.81E-06 in summer and the minimum was 2.27E-07 in winter. The sensitivity analysis revealed that the level of V. parahaemolyticus in shellfish and the amount of shellfish consumed per meal were main factors contributing to illness. This QMRA provided valuable information such as the probability of illness associated with the consumption of shellfish and reference points for prevention strategies and control standards of V. parahaemolyticus in shellfish.

HIGHLIGHTS

Vibrio parahaemolyticus Is Associated with Diarrhea Cases in Mexico, with a Dominance of Pandemic O3:K6 Clones

In the present study, we conducted surveillance of the V. parahaemolyticus strains present in clinical samples from six geographical regions of Mexico (22 states) from 2004 to 2011. The serotype dominance, virulence genes, presence of pandemic O3:K6 strains, and antibiotic resistance of the isolates were investigated. In total, 144 strains were isolated from the clinical samples. Seven different O serogroups and twenty-five serovars were identified. Most clinical isolates (66%, 95/144) belonged to the pandemic clone O3:K6 (tdh+, toxRS/new+ and/or orf8+) and were detected in 20 of the 22 states. Among the pandemic clones, approximately 17.8% (17/95) of the strains cross-reacted with the antisera for the K6 and K59 antigens (O3:K6, K59 serotype). Other pathogenic strains (tdh+ and/or trh+, toxRS/new-, orf8-) accounted for 26.3%, and the nonpathogenic strains (tdh- and/or trh-) accounted for 7.6%. Antimicrobial susceptibility testing showed that most of the strains were resistant to ampicillin (99.3%) but were sensitive to most tested antibiotics. The level of multidrug resistance was 1.3%. Our results indicate that pandemic O3:K6 is present in most Mexican states, thus, constant surveillance of V. parahaemolyticus strains in diarrhea patients is a public health priority and is useful for conducting risk assessments of foodborne illnesses to prevent V. parahaemolyticus outbreaks. Overall, our observations indicate that the pandemic O3:K6 clone of V. parahaemolyticus has become a relatively stable subpopulation and may be endemically established in Mexico; therefore, constant surveillance is needed to avoid new outbreaks of this pathogen.

On-Farm Practices Associated with Multi-Drug-Resistant Escherichia coli and Vibrio parahaemolyticus Derived from Cultured Fish

Aquaculture activities have been implicated as responsible for the emergence of antimicrobial resistance (AMR), leading to broad dissemination and transference of antibiotic resistance to pathogens that affect humans and animals. The current study investigates the on-farm practices and environmental risk factors that can potentially drive the development and emergence of multi-drug-resistant (MDR) Escherichia coli and Vibrio parahaemolyticus in the aquaculture system. A cross-sectional study was conducted on 19 red hybrid tilapia (Oreochromis spp.) and 13 Asian seabass (Lates calcarifer, Bloch 1970) farms on the west coast of peninsular Malaysia. Data were collected using a structured questionnaire pertaining to farm demography, on-farm management practices and environmental characteristics. Multi-drug-resistant E. coli (n = 249) and V. parahaemolyticus (n = 162) isolates were analyzed using multi-level binary logistic regression to identify important drivers for the occurrence and proliferation of the MDR bacteria. On-farm practices such as manuring the pond (OR = 4.5; 95% CI = 1.21–16.57) were significantly associated with the occurrence of MDR E. coli, while earthen ponds (OR = 8.2; 95% CI = 1.47–45.2) and human activity adjacent to the farm (OR = 4.6; 95% CI = 0.75–27.98) were associated with an increased likelihood of MDR V. parahaemolyticus. Considering the paucity of information on the drivers of AMR in the aquaculture production in this region, these findings indicate the targeted interventions implementable at aquaculture farms to efficiently abate the risk of MDR amongst bacteria that affect fish that are of public health importance.

Diarrhea-Causing Bacteria and Their Antibiotic Resistance Patterns Among Diarrhea Patients From Ghana

Diarrheal disease remains a major global health problem particularly in children under 5 years and the emergence of antibiotic-resistant strains of causative pathogens could slow control efforts, particularly in settings where treatment options are limited. This surveillance study conducted in Ghana aimed to determine the prevalence and antimicrobial susceptibility profile of diarrhea-causing bacteria. This was a cross-sectional study carried out in five health facilities in the Ga West Municipality of Ghana between 2017 and 2021. Diarrheic stool samples from patients were collected and cultured on standard differential/selective media and isolates identified by standard biochemical tests, MALDI-TOF assay, and serological analysis. The antibiogram was determined using Kirby-Bauer disk diffusion and Microscan autoScan4 MIC panels which were used for extended-spectrum beta-lactamase (ESBL) detection. Bacteria were isolated from 97.5% (772/792) of stool samples, and 167 of the isolates were diarrheagenic and met our inclusion criteria for antimicrobial resistance (AMR) analysis. These included Escherichia coli (49.1%, 82/167), Salmonella species (23.9%, 40/167), Vibrio species (16.8%, 28/167), and Shigella species (10.2%, 17/167). Among 24 Vibrio species, we observed resistances to cefotaxime (21/24, 87.5%), ceftriaxone (20/24, 83.3%), and ciprofloxacin (6/24, 25%), including four multi-drug resistant isolates. All 13 Vibrio parahaemolyticus isolates were resistant to cefazolin. All 17 Shigella isolates were resistant to tetracycline with resistance to shigellosis drugs such as norfloxacin and ciprofloxacin. Salmonella isolates were highly susceptible to norfloxacin (40/40, 100%) and tetracycline (12/34, 35%). Two ESBL-producing E. coli were also identified with marked susceptibility to gentamicin (66/72, 91.7%) and amikacin (57/72, 79.2%) prescribed in the treatment of E. coli infections. This study showed the different bacteria implicated in diarrhea cases in Ghana and the need for differential diagnoses for better treatment outcomes. Escherichia coli, Shigella, Salmonella, and Vibrio have all been implicated in diarrhea cases in Ghana. The highest prevalence was E. coli and Salmonella with Shigella the least prevalent. Resistance to commonly used drugs found in these isolates may render bacteria infection treatment in the near future nearly impossible. Routine antimicrobial susceptibility testing, effective monitoring, and nationwide surveillance of AMR pathogens should be implemented to curb the increase of antimicrobial resistance in Ghana.

Quantification and Antimicrobial Resistance of Vibrio parahaemolyticus in Retail Seafood in Hanoi, Vietnam

ABSTRACT

Vibrio parahaemolyticus is a major cause of foodborne diseases and a significant threat to human health worldwide. Most of the infections caused by V. parahaemolyticus are usually associated with the consumption of raw or undercooked seafood. This study was conducted to determine the prevalence, quantitative load, and antimicrobial resistance of V. parahaemolyticus in retail seafood in Hanoi, Vietnam. A total of 120 seafood samples consisting of marine fish (n = 30), oysters (n = 30), shrimp (n = 30), and squid (n = 30) were purchased from different traditional markets in Hanoi between May and October 2020. Isolation of V. parahaemolyticus was based on ISO/TS 21872-1:2017, and the most-probable-number (MPN) method was used for quantification. The disk diffusion method was applied for antimicrobial susceptibility testing. Overall, V. parahaemolyticus was detected in 58.33% of the samples. V. parahaemolyticus was most commonly isolated in shrimp samples, with a prevalence of 86.67%, followed by fish (53.33%), squid (53.33%), and oysters (40%). One V. parahaemolyticus isolate from an oyster carrying the trh gene was detected. Of the positive samples, 27.14% contained V. parahaemolyticus counts of less than 2 log MPN/g, whereas 44.29% ranged from 2 to 4 log MPN/g and 28.57% contained more than 4 log MPN/g. Regarding antimicrobial resistance, 85.71% of V. parahaemolyticus isolates were resistant to at least one antibiotic tested. The highest rate of resistance was observed against ampicillin (81.43%), followed by cefotaxime (11.43%), ceftazidime (11.43%), trimethoprim-sulfamethoxazole (8.57%), and tetracycline (2.86%). The results demonstrate the high prevalence and quantitative load and the antimicrobial resistance of V. parahaemolyticus isolated from seafood sold in the study area.

HIGHLIGHTS

Diversity, abundances and distribution of antibiotic resistance genes and virulence factors in the South China Sea revealed by metagenomic sequencing

Antibiotic resistance genes (ARGs) and virulence factors (VFs) pose considerable health risks to humans. The occurrence and abundance of several typical ARGs in the sea have been widely investigated. However, the full profiles and abundances of the antibiotic resistome and VFs in the South China Sea remain unexplored. Therefore, in this study, we investigated the full profiles of the ARGs and VFs, as well as their abundances and distribution, in the South China Sea using metagenomic approaches. In total, 140 ARG subtypes and 155 VFs were detected. The most abundant ARG was multidrug resistance gene, followed by bacitracin resistance gene. Flagella was the most abundant VF. Pearson correlation analysis revealed a strong and positive correlation between the abundances of ARGs and VFs. Redundancy analysis and co-occurrence network analysis showed that the predominant VFs were positively correlated with the predominant ARGs in the South China Sea. Nonmetric multidimensional scaling and Procrustes analyses demonstrated that the sampling sites were clustered into three compartments according to the geographical location, i.e., offshore, open sea, and reef zones. The abundances of ARGs and VFs in the offshore zone were much higher than those in the open sea and reef zones (p < 0.05). Several physico-chemical factors most closely associated with anthropogenic activities, i.e., nitrate, lead, copper, and zinc, were positively correlated with the predominant ARGs and VFs in the South China Sea. Our results suggest that the ocean is a large reservoir of diverse and abundant ARGs and VFs, which may threaten human health and seafood safety. These findings improve the understanding of the relationship between ARG dissemination and intensive anthropogenic activities and can aid in improving ocean management and seafood product safety.

Recovery of Pasteurization-Resistant Vibrio parahaemolyticus from Seafoods Using a Modified, Two-Step Enrichment

Persistent Vibrio-parahaemolyticus-associated vibriosis cases, attributed, in part, to the inefficient techniques for detecting viable-but-non-culturable (VBNC) Vibrio pathogens and the ingestion of undercooked seafood, is the leading cause of bacterial seafood-borne outbreaks, hospitalizations, and deaths in the United States. The effect of extreme heat processing on Vibrio biology and its potential food safety implication has been underexplored. In the present work, environmental samples from the wet market, lagoon, and estuarine environments were analyzed for V. parahaemolyticus recovery using a modified, temperature-dependent, two-step enrichment method followed by culture-based isolation, phenotype, and genotype characterizations. The work recovered novel strains (30% of 12 isolates) of V. parahaemolyticus from prolonged-heat-processing conditions (80 °C, 20 min), as confirmed by 16S rDNA bacterial identification. Select strains, VHT1 and VHT2, were determined to be hemolysis- and urease-positive pathogens. PCR analyses of chromosomal DNA implicated the tdh-independent, tlh-associated hemolysis in these strains. Both strains exhibited significant, diverse antibiotic profiles (p < 0.05). Turbidimetric and viable count assays revealed the pasteurization-resistant V. parahaemolyticus VHT1/VHT2 (62 °C, 8 h). These findings disclose the efficiency of Vibrio extremist recovery by the modified, two-step enrichment technique and improve knowledge of Vibrio biology essential to food safety reformation.

Prevalence and Antimicrobial Resistance of Escherichia coli, Salmonella and Vibrio Derived from Farm-Raised Red Hybrid Tilapia (Oreochromis spp.) and Asian Sea Bass (Lates calcarifer, Bloch 1970) on the West Coast of Peninsular Malaysia

Antibiotics are widely used in intensive fish farming, which in turn increases the emergence of antimicrobial-resistant (AMR) bacteria in the aquatic environment. The current study investigates the prevalence and determines the antimicrobial susceptibility of E. coli, Salmonella, and Vibrio in farmed fishes on the west coast of Peninsular Malaysia. Over a period of 12 months, 32 aquaculture farms from the Malaysian states of Selangor, Negeri Sembilan, Melaka, and Perak were sampled. Both E. coli and Salmonella were highly resistant to erythromycin, ampicillin, tetracycline, and trimethoprim, while Vibrio was highly resistant to ampicillin and streptomycin. Resistance to the antibiotics listed as the highest priority and critically important for human therapy, such as colistin in E. coli (18.1%) and Salmonella (20%) in fish, is a growing public health concern. The multi-drug resistance (MDR) levels of E. coli and Salmonella in tilapia were 46.5% and 77.8%, respectively. Meanwhile, the MDR levels of E. coli, Salmonella, V. parahaemolyticus, V. vulnificus and V. cholerae in Asian seabass were 34%, 100%, 21.6%, 8.3% and 16.7%, respectively. Our findings provide much-needed information on AMR in aquaculture settings that can be used to tailor better strategies for the use of antibiotics in aquaculture production at the local and regional levels.

Occurrence of Vibrio parahaemolyticus and Staphylococcus aureus in seafood

The objective of this study was to establish the occurrence of Vibrio parahaemolyticus and Staphylococcus aureus in several species of sea fish and mussels (Mytilus galloprovincialis). The study included a total of 33 samples of frozen sea fish and 64 samples of fresh wild and farmed mussels purchased from the stores. V. parahaemolyticus was isolated and confirmed via PCR in 2 (6%) fish samples (Atlantic cod and Alaska pollock) and 20 (31%) mussel samples. S. aureus was also isolated and confirmed via PCR in 2 (6%) fish samples (Argentine hake and Atlantic cod). Significant differences were found in the total bacterial contamination between wild mussels (6.54 log cfu/g) and farmed mussels (6.69 log cfu/g). Total V. parahaemolyticus count did not show significant differences either between wild (4.45 log cfu/g) and farmed mussels (4.99 log cfu/g). In wild mussels the S. aureus count was found to be 4.50 log cfu/g, while in farmed mussels it was 3.14 log cfu/g. The occurrence of V. parahaemolyticus and S. aureus in fish and mussels presents a risk to the consumer's health.

Quantitative microbiological risk assessment of complex microbial community in Prawn farm wastewater and applicability of nanoparticles and probiotics for eliminating of antibiotic-resistant bacteria

The current review highlighted the quantitative microbiological risk assessment of Vibrio parahaemolyticus in Prawn farm wastewaters (PFWWs) and the applicability of nanoparticles for eliminating antibiotic-resistant bacteria (ARB). The high availability of the antibiotics in the environment and their transmission into human through the food-chain might cause unknown health effects. The aquaculture environments are considered as a reservoir for the antibiotic resistance genes (ARGs) and contributed effectively in the increasing of ABR. The metagenomic analysis is used to explore ARGs in the non-clinical environment. V. parahaemolyticus is among the pathogenic bacteria which are transmitted through sea food causing human acute gastroenteritis due to available thermostable direct hemolysin (tdh), adhesins, TDH related hemolysin (trh). The inactivation of pathogenic bacteria using nanoparticles act by disturbing the cell membrane, interrupting the transport system, DNA and mitochondria damage, and oxidizing the cellular component by reactive oxygen species (ROS). The chloramphenicol, nitrofurans, and nitroimidazole are among the prohibited drugs in fish and fishery product. The utilization of probiotics is the most effective and safe alternative for antibiotics in Prawn aquaculture. This review will ensure public understanding among the readers on how they can decrease the risk of the antimicrobial resistance distribution in the environment.

Whole genome sequencing reveals great diversity of Vibrio spp in prawns at retail

Consumption of prawns as a protein source has been on the rise worldwide with seafood identified as the predominant attributable source of human vibriosis. However, surveillance of non-cholera Vibrio is limited both in public health and in food. Using a population- and market share-weighted study design, 211 prawn samples were collected and cultured for Vibrio spp. Contamination was detected in 46 % of samples, and multiple diverse Vibrio isolates were obtained from 34 % of positive samples. Whole genome sequencing (WGS) and phylogenetic analysis illustrated a comprehensive view of Vibrio species diversity in prawns available at retail, with no known pathogenicity markers identified in Vibrio parahaemolyticus and V. cholerae. Antimicrobial resistance genes were found in 77 % of isolates, and 12 % carried genes conferring resistance to three or more drug classes. Resistance genes were found predominantly in V. parahaemolyticus, though multiple resistance genes were also identified in V. cholerae and V. vulnificus. This study highlights the large diversity in Vibrio derived from prawns at retail, even within a single sample. Although there was little evidence in this study that prawns are a major source of vibriosis in the UK, surveillance of non-cholera Vibrio is very limited. This study illustrates the value of expanding WGS surveillance efforts of non-cholera Vibrios in the food chain to identify critical control points for food safety through the production system and to determine the full extent of the public health impact.

Vibrio parahaemolyticus CadC regulates acid tolerance response to enhance bacterial motility and cytotoxicity

Pathogens adapted to sub-lethal acidic conditions could increase the virulence and survival ability under lethal conditions. In the aquaculture industry, feed acidifiers have been used to increase the growth of aquatic animals. However, there is limited study on the effects of acidic condition on the virulence and survival of pathogens in aquaculture. In this study, we investigated the survival ability of Vibrio parahaemolyticus at lethal acidic pH (4.0) after adapted the bacteria to sub-lethal acidic pH (5.5) for 1 hr. Our results indicated that the adapted strain increased the survival ability at lethal acidic pH invoked by an inorganic (HCl) or organic (citric) acid. RNA-sequencing (RNA-seq) results revealed that 321 genes were differentially expressed at the sub-lethal acidic pH including cadC, cadBA and groES/groEL relating to acid tolerance response (ATR), as well as genes relating to outer membrane, heat-shock proteins, phosphotransferase system and flagella system. Quantitative real-time polymerase chain reaction (qRT-PCR) confirmed that cadC and cadBA were upregulated under sub-lethal acidic conditions. The CadC protein could directly regulate the expression of cadBA to modulate the ATR in V. parahaemolyticus. RNA-seq data also indicated that 113 genes in the CadC-dependent way and 208 genes in the CadC-independent way were differentially expressed, which were related to the regulation of ATR. Finally, the motility and cytotoxicity of the sub-lethal acidic adapted wild type (WT) were significantly increased compared with the unadapted strain. Our results demonstrated that the dietary acidifiers may increase the virulence and survival of V. parahaemolyticus in aquaculture.

Foodborne Pathogenic Vibrios: Antimicrobial Resistance

Foodborne illness caused by pathogenic Vibrios is generally associated with the consumption of raw or undercooked seafood. Fish and other seafood can be contaminated with Vibrio species, natural inhabitants of the marine, estuarine, and freshwater environment. Pathogenic Vibrios of major public health concerns are Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus. Common symptoms of foodborne Vibrio infection include watery diarrhea, stomach cramping, nausea, vomiting, fever, and chills. Administration of oral or intravenous rehydration salts solution is the mainstay for the management of cholera, and antibiotics are also used to shorten the duration of diarrhea and to limit further transmission of the disease. Currently, doxycycline, azithromycin, or ciprofloxacin are commonly used for V. cholerae, and doxycycline or quinolone are administered for V. parahaemolyticus, whereas doxycycline and a third-generation cephalosporin are recommended for V. vulnificus as initial treatment regimen. The emergence of antimicrobial resistance (AMR) in Vibrios is increasingly common across the globe and a decrease in the effectiveness of commonly available antibiotics poses a global threat to public health. Recent progress in comparative genomic studies suggests that the genomes of the drug-resistant Vibrios harbor mobile genetic elements like plasmids, integrating conjugative elements, superintegron, transposable elements, and insertion sequences, which are the major carriers of genetic determinants encoding antimicrobial resistance. These mobile genetic elements are highly dynamic and could potentially propagate to other bacteria through horizontal gene transfer (HGT). To combat the serious threat of rising AMR, it is crucial to develop strategies for robust surveillance, use of new/novel pharmaceuticals, and prevention of antibiotic misuse.

Prevalence and Characterization of Food-Borne Vibrio parahaemolyticus From African Salad in Southern Nigeria

The demand for minimally processed vegetables (African salad) has increased partly due to its inclusion in ready-to-eat foods. Nevertheless, the associated risk of the presence of emergent foodborne pathogens, such as Vibrio parahaemolyticus might be underestimated. The present study was designed to isolate and characterize foodborne V. parahaemolyticus from minimally processed vegetables using culture-based methods and molecular approach. A total of 300 samples were examined from retail outlets between November 2018 and August 2019 from Southern Nigeria. The prevalence of vibrios from the overall samples based on the colonial proliferation of yellow, blue-green and/or green colonies on thiosulfate citrate bile salts sucrose agar was 74/300 (24.6%). An average of two green or blue-green colonies from respective plates was screened for V. parahaemolyticus using analytical profile index (API) 20 NE. Polymerase chain reaction further confirmed the identity of positive V. parahaemolyticus. The counts of V. parahaemolyticus ranged from 1.5 to 1,000 MPN/g. A total of 63 recovered V. parahaemolyticus were characterized further. The resistance profile of the isolates include ampicillin 57/63 (90.5%), cefotaxime 41/63 (65.1%), ceftazidime 30/63 (47.6%), amikacin 32/63 (50.8%), kanamycin 15/63 (23.8%), and oxytetracycline 16/63 (25.4%). The multiple antibiotic index ranged from 0–0.81. The formation of biofilm by the isolates revealed the following: strong formation 15/63 (23.8%), moderate formation 31/63 (49.2%), weak formation 12/63 (19.1%), and no formation 5/63 (7.9%). A total of 63/63 (100%), 9/63 (14.3%), and 20/63 (31.8%) of the isolates harbored the tox R gene, TDH-related hemolysin (trh) and thermostable direct hemolysin (tdh) determinants respectively. The isolates with O2 serogroup were most prevalent via PCR. Isolates that were resistant to tetracycline, kanamycin, and chloramphenicol possessed resistant genes. The presence of multidrug-resistant vibrios in the minimally processed vegetables constitutes a public health risk and thus necessitates continued surveillance.

Motility, biofilm formation and associated gene expression in Vibrio parahaemolyticus impaired by co-culture with live Ulva fasciata

AIMS

Vibrio parahaemolyticus is one of the most frequently occurred pathogens in mariculture. This study aimed to explore the mechanism of the impact of Ulva fasciata on the motility and biofilm formation of V. parahaemolyticus.

METHODS AND RESULTS

The inhibitory effect of U. fasciata on a V. parahaemolyticus, isolated from clam maricultural sediment, was examined by co-culture of them. The live U. fasciata significantly inhibited the swimming behaviour, twitching behaviour and biofilm formation of V. parahaemolyticus JF, with inhibition rates range of 2.48%-20.26%, 1.59%-39.18% and 28.3%-94.7% under different nitrate and phosphate levels, respectively. The results of transcriptome sequencing showed that 210 significantly differentially expressed genes (DEGs) were found in strain JF between the presence and absence of U. fasciata, including 90 upregulated genes and 120 downregulated genes. According to GO (Gene Ontology) function enrichment and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis, the downregulated genes of JF were partially enriched in flagella assembly (fliC, fliK, fliG, fliN, fliH, fliI, fliJ and fliA), bacterial chemotaxis (mCP, cheB, cheW and cheY) and biofilm formation (fliA/σ²⁸ and eps), which explained the suppressed motility and biofilm formation of V. parahaemolyticus JF under U. fasciata stress.

CONCLUSIONS

Live U. fasciata significantly impaired the motility and biofilm formation of V. parahaemolyticus, which could occur in niches with either sufficient or inadequate nutrient (nitrate and phosphate) concentrations. The DEGs of V. parahaemolyticus modulated by U. fasciata were enriched mainly in the flagellar assembly, bacterial chemotaxis and biofilm pathways.

SIGNIFICANCE AND IMPACT OF THE STUDY

New information on how V. parahaemolyticus respond to U. fasciata regarding motility and adhesion behaviours, and the mechanism of that was firstly explored in this study. The results suggested that the seaweed U. fasciata has promising prospects as an environmentally friendly preventive measure to treat vibriosis in mariculture.

Characterization and Analysis of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) in Pandemic and Non-Pandemic Vibrio parahaemolyticus Isolates from Seafood Sources

Vibrio parahaemolyticus is one of the significant seafood-borne pathogens causing gastroenteritis in humans. Clustered regularly interspaced short palindromic repeats (CRISPR) are commonly detected in the genomes of V. parahaemolyticus and the polymorphism of CRISPR patterns has been applied as a genetic marker for tracking its evolution. In this work, a total of 15 pandemic and 36 non-pandemic V. parahaemolyticus isolates obtained from seafood between 2000 and 2012 were characterized based on hemolytic activity, antimicrobial susceptibility, and CRISPR elements. The results showed that 15/17 of the V. parahaemolyticus seafood isolates carrying the thermostable direct hemolysin gene (tdh+) were Kanagawa phenomenon (KP) positive. The Multiple Antibiotic Resistance (MAR) index ranged between 0.1 and 0.4, and 45% of the isolates have an MAR index ≥ 0.2. A total of 19 isolates were positive for CRISPR detection, including all tdh+ trh− isolates, two of tdh− trh+, and each of tdh+ trh+ and tdh− trh−. Four spacer types (Sp1 to Sp4) were identified, and CRISPR-positive isolates had at least one type of spacer homolog to the region of Vibrio alginolyticus megaplasmid. It is of interest that a specific CRISPR profile and spacer sequence type was observed with correlations to the hemolysin genotype (tdh/trh). Thus, these provide essential data on the exposure of foreign genetic elements and indicate shared ancestry within different genotypes of V. parahaemolyticus isolates.