Distribution of phenotypic and genotypic antimicrobial resistance and virulence genes in Vibrio parahaemolyticus isolated from cultivated oysters and estuarine water

Implication of environmental factors on the pathogenicity of Vibrio vulnificus: Insights into gene activation and disease outbreak

Climate change, particularly rising sea surface temperatures and altered salinity levels has contributed to the increased prevalence of Vibrio vulnificus infections in humans and marine life. This opportunistic pathogen thrives in warm, estuarine environments, and its virulence is influenced by temperature-dependent gene expression, such as the activation of pVvBt2. Elevated temperatures and iron availability enhance pathogenicity by upregulating key virulence factors, including hemolysin, exotoxins, and biofilm-associated genes. Climate-driven shifts in microbial ecology have also facilitated the global expansion of V. vulnificus, leading to more frequent outbreaks and an increasing threat to public health. The unregulated use of antibiotics has also contributed to the emergence of resistant strains, complicating treatment strategies. This review explores the complex interplay between climate change and the molecular mechanisms driving V. vulnificus pathogenicity, global gene expression responses, and the implications for disease outbreaks. We also discuss current and emerging therapeutic approaches, including antibiotic stewardship and vaccine development, to mitigate the rising health risks posed by this climate-sensitive pathogen.

Further Evidence of Anthropogenic Impact: High Levels of Multiple-Antimicrobial-Resistant Bacteria Found in Neritic-Stage Sea Turtles

BACKGROUND/OBJECTIVES

Marine turtles are globally threatened and face daily anthropogenic threats, including pollution. Water pollution from emerging contaminants such as antimicrobials is a major and current environmental concern.

METHODS

This study investigated the phenotypic antimicrobial resistance and heavy metal resistance genes of 47 Vibrio isolates from different stages of sea turtles (oceanic stage vs neritic stage) from the Taiwanese coast.

RESULTS

The results show that a high proportion (48.9%; 23/47) of the Vibrio species isolated from sea turtles in our study had a multiple antimicrobial resistance (MAR) pattern. It was found that Vibrio spp. isolates with a MAR pattern and those with a MAR index value greater than 0.2 were both more likely to be observed in neritic-stage sea turtles. Furthermore, isolates from neritic-stage sea turtles exhibited greater resistance to the majority of antimicrobials tested (with the exception of beta-lactams and macrolides) than isolates from the oceanic-stage groups. Isolates from neritic sea turtles were found to be more resistant to nitrofurans and aminoglycosides than isolates from oceanic sea turtles. Furthermore, isolates with a MAR pattern (p = 0.010) and those with a MAR index value greater than 0.2 (p = 0.027) were both found to be significantly positively associated with the mercury reductase (merA) gene.

CONCLUSIONS

The findings of our study indicate that co-selection of heavy metals and antimicrobial resistance may occur in aquatic bacteria in the coastal foraging habitats of sea turtles in Taiwan.

Spotlight on the epidemiology and antimicrobial susceptibility profiles of Vibrio species in the MENA region, 2000-2023

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.

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.

Seasonal and anthropogenic influences on bacterioplankton communities: ecological impacts in the coastal waters of Qinhuangdao, Northern China

Marine bacterioplankton play a crucial role in the cycling of carbon, nitrogen, and phosphorus in coastal waters. And the impact of environmental factors on bacterial community structure and ecological functions is a dynamic ongoing process. To systematically assess the relationship between environmental changes and bacterioplankton communities, this study delved into the spatiotemporal distribution and predicted metabolic characteristics of bacterioplankton communities at two estuarine beaches in Northern China. Coastal water samples were collected regularly in spring, summer, and autumn, and were analyzed in combination with environmental parameters and bacterioplankton community. Results indicated significant seasonal variations in bacterioplankton communities as Bacteroidetes and Actinobacteria were enriched in spring, Cyanobacteria proliferated in summer. While Pseudomonadota and microorganisms associated with organic matter decomposition prevailed in autumn, closely linked to seasonal variation of temperature, light and nutrients such as nitrogen and phosphorus. Particularly in summer, increased tourism activities and riverine inputs significantly raised nutrient levels, promoting the proliferation of specific photosynthetic microorganisms, potentially linked to the occurrence of phytoplankton blooms. Spearman correlation analysis further revealed significant correlations between bacterioplankton communities and environmental factors such as salinity, chlorophyll a, and total dissolved phosphorus (TDP). Additionally, the metabolic features of the spring bacterioplankton community were primarily characterized by enhanced activities in the prokaryotic carbon fixation pathways, reflecting rapid adaptation to increased light and temperature, as well as significant contributions to primary productivity. In summer, the bacterial communities were involved in enhanced glycolysis and biosynthetic pathways, reflecting high energy metabolism and responses to increased light and biomass. In autumn, microorganisms adapted to the accelerated decomposition of organic matter and the seasonal changes in environmental conditions through enhanced amino acid metabolism and material cycling pathways. These findings demonstrate that seasonal changes and human activities significantly influence the structure and function of bacterioplankton communities by altering nutrient dynamics and physical environmental conditions. This study provides important scientific insights into the marine biological responses under global change.

Multidrug resistant Vibrio spp. identified from mussels farmed for human consumption in Central Italy

AIMS

This study investigated phenotypic and genotypic antimicrobial resistance profiles of Vibrio strains identified from Mytilus galloprovincialis farmed for human consumption in the Adriatic Sea Central Italy.

METHODS AND RESULTS

A total of 475 mussels (M. galloprovincialis) were involved in the present study, and culture-dependent microbiological methods permitted to identify a total of 50 Vibrio strains that were tested for antibiotic susceptibility followed by the genetic determinant detections. Antibiograms showed resistance against ampicillin (36.0%), amoxicillin-clavulanic acid (30.0%), gentamycin (14.0%), and imipenem (18.0%). Biomolecular assays amplified a total of 264 antibiotic resistance genes harbored by both susceptible and resistant Vibrio species. Among resistance genes, aacC2 (62.0%) and aadA (58.0%) for aminoglycosides, blaTEM (54.0%) for beta-lactams, qnrS (24.0%) for quinolones, tetD (66.0%) for tetracyclines, and vanB (60.0%) for glycopeptides were mainly amplified by PCR assays.

CONCLUSIONS

Vibrio genus is involved in the antibiotic resistance phenomenon diffusion in the aquatic environments, as demonstrated by the harboring of many genetic determinants representing a kind of genetic "dark world".

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.

Surveillance of Vibrio parahaemolyticus pathogens recovered from ready-to-eat foods

This study examined the occurrence of V. parahaemolyticus from ready-to-eat (RTE) food in Delta State, Nigeria. It also characterized antibiotic resistance and virulence gene profile patterns to determine the associated health risk hazard. Food samples total of 380 were collected randomly and assessed for V. parahaemolyticus. V. parahaemolyticus isolates were characterized for their virulence and antibiogram potentials using a phenotypic and polymerase chain reaction (PCR) approach. A total of 42 (11.1%) samples were contaminated with V. parahaemolyticus. In 17/42 (40.5%) of the V. parahaemolyticus-positive samples, the densities were < 10 MPN/g. However, 19/42 (45.2%) and 6/42 (14.3%) of the samples had densities of 10 - 10² and > 10² MPN/g, respectively. A total of 67 V. parahaemolyticus isolates were identified using PCR; 54(80.6%) isolates were multidrug resistant. A total of 22 (32.8%), 39 (58.2%), and 67 (100%) of the V. parahaemolyticus harbored the tdh, trh, and tlh toxin genes, respectively. The T3SS1 gene (vcrD1) was detected in 67 (100%) of the isolates. The T3SS2α genes which were vcrD2, vopB2, and vopT were detected in 21 (31.3%), 11 (16.4%) and 30 (44.8%) of the isolates respectively. Some of the V. parahaemolytics strains harbored the orf8 gene 20 (29.9%), and a combination of orf8 + tdh genes 12 (17.9%), categorized as pandemic strains. The antibiotic resistance genes detected in this study include bla_TEM 33 (49.3), tetM 19 (28.4), cmlA 32(47.8) and sul1 14 (20.9). The concentration levels and prevalence of V. parahaemolyticus in RTE foods indicate contamination of ready-to-eat foods, particularly street foods consumed in the Delta State of Nigeria, threatening public health and consumer safety.

Detection of virulence, antimicrobial resistance, and heavy metal resistance properties in Vibrio anguillarum isolated from mullet (Mugil cephalus) cultured in Korea

In the present study, we identified and characterized 22 strains of V. anguillarum from 145 samples of mullets (Mugill cephallus) cultured in several fish farms in South Korea. They were subjected to pathogenicity tests, antimicrobial susceptibility test, and broth dilution test to detect virulence markers, antimicrobial resistance, and heavy metal resistance properties. All the isolates showed amylase and caseinase activity, followed by gelatinase (90.9%), DNase (45.5%), and hemolysis activities (α = 81.1% and β = 18.2%). The PCR assay revealed that isolates were positive for VAC, ctxAB, AtoxR, tdh, tlh, trh, Vfh, hupO, VPI, and FtoxR virulence genes at different percentages. All the isolates showed multi-drug resistance properties (MAR index ≥ 0.2), while 100% of the isolates were resistant to oxacillin, ticarcillin, streptomycin, and ciprofloxacin. Antimicrobial resistance genes, qnrS (95.5%), qnrB (86.4%), and StrAB (27.3%), were reported. In addition, 40.9% of the isolates were cadmium-tolerant, with the presence of CzcA (86.4%) heavy metal resistance gene. The results revealed potential pathogenicity associated with V. anguillarum in aquaculture and potential health risk associated with consumer health.

When Vibrios Take Flight: A Meta-Analysis of Pathogenic Vibrio Species in Wild and Domestic Birds

Of the over 100 species in the genus Vibrio, approximately twelve are associated with clinical disease, such as cholera and vibriosis. Crucially, eleven of those twelve, including Vibrio cholerae and Vibrio vulnificus, have been isolated from birds. Since 1965, pathogenic Vibrio species have been consistently isolated from aquatic and ground-foraging bird species, which has implications for public health, as well as the One Health paradigm defined as an ecology-inspired, integrative framework for the study of health and disease, inclusive of environmental, human, and animal health. In this meta-analysis, we identified 76 studies from the primary literature which report on or examine birds as hosts for pathogenic Vibrio species. We found that the burden of disease in birds was most commonly associated with V. cholerae, followed by V. metschnikovii and V. parahaemolyticus. Meta-analysis wide prevalence of our Vibrio pathogens varied from 19% for V. parahaemolyticus to 1% for V. mimicus. Wild and domestic birds were both affected, which may have implications for conservation, as well as agriculturally associated avian species. As pathogenic Vibrios become more abundant throughout the world as a result of warming estuaries and oceans, susceptible avian species should be continually monitored as potential reservoirs for these pathogens.

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.

Occurrence and Molecular Characterization of Potentially Pathogenic Vibrio spp. in Seafood Collected in Sicily

Seafood can vehiculate foodborne illnesses from water to humans. Climate changes, increasing water contamination and coastlines anthropization, favor the global spread of Vibrio spp. and the occurrence of antibiotic-resistant isolates. The aim of this study was to evaluate the spread of potentially pathogenic Vibrio spp. in fishery products collected in Sicily and to assess their antibiotic resistance. Bacteriological and molecular methods were applied to 603 seafood samples to detect V. parahaemolyticus, V. cholerae, V. vulnificus, and Vibrio alginolyticus in order to assess their pathogenicity and antimicrobial resistance. About 30% of bivalves and 20% of other fishery products were contaminated by Vibrio spp.; V. parahaemolyticus accounted for 43/165 isolates, 3 of which were carrying either tdh or trh; V. cholerae accounted for 12/165 isolates, all of them non-O1 non-O139 and none carrying virulence genes; and V. vulnificus accounted for 5/165 isolates. The highest rates of resistance were observed for ampicillin, but we also detected strains resistant to antibiotics currently included among the most efficient against Vibrio spp. In spite of their current low incidence, their rise might pose further issues in treating infections; hence, these results stress the need for a continuous monitoring of antimicrobial resistance among fishery products and an effective risk assessment.

Molecular Epidemiology of Antimicrobial Resistance and Virulence Profiles of Escherichia coli, Salmonella spp., and Vibrio spp. Isolated from Coastal Seawater for Aquaculture

The occurrence of waterborne antimicrobial-resistant (AMR) bacteria in areas of high-density oyster cultivation is an ongoing environmental and public health threat given the popularity of shellfish consumption, water-related human recreation throughout coastal Thailand, and the geographical expansion of Thailand's shellfish industry. This study characterized the association of phenotypic and genotypic AMR, including extended-spectrum β-lactamase (ESBL) production, and virulence genes isolated from waterborne Escherichia coli (E. coli) (n = 84), Salmonella enterica (S. enterica) subsp. enterica (n = 12), Vibrio parahaemolyticus (V. parahaemolyticus) (n = 249), and Vibrio cholerae (V. cholerae) (n = 39) from Thailand's coastal aquaculture regions. All Salmonella (100.0%) and half of V. cholerae (51.3%) isolates harbored their unique virulence gene, invA and ompW, respectively. The majority of isolates of V. parahaemolyticus and E. coli, ~25% of S. enterica subsp. enterica, and ~12% of V. cholerae, exhibited phenotypic AMR to multiple antimicrobials, with 8.9% of all coastal water isolates exhibiting multidrug resistance (MDR). Taken together, we recommend that coastal water quality surveillance programs include monitoring for bacterial AMR for food safety and recreational water exposure to water for Thailand's coastal water resources.

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

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

Aquatic environments: A Potential Source of Antimicrobial-Resistant Vibrio spp

Vibrio spp. are associated with water and seafood-related outbreaks worldwide. They are naturally present in aquatic environments such as seawater, brackish water and freshwater environments. These aquatic environments serve as the main reservoirs of antimicrobial-resistant genes and promote the transfer of antimicrobial-resistant bacterial species to aquatic animals and humans through the aquatic food chain. Vibrio spp. are known as etiological agents of cholera and non-cholera Vibrio infections in humans and animals. Antimicrobial-resistant Vibrio species have become a huge threat in regard to treating Vibrio infections in aquaculture and public health. Most of the Vibrio spp. possess resistance towards the commonly used antimicrobials, including β-lactams, aminoglycosides, tetracyclines, sulfonamides, quinolones and macrolides. The aim of this review is to summarize the antimicrobial resistance properties of Vibrio spp. isolated from aquatic environments to provide awareness about potential health risks related to Vibrio infections in aquaculture and public health.

Characteristics of Antimicrobial-Resistant Vibrio parahaemolyticus Strains and Identification of Related Antimicrobial Resistance Gene Mutations

Multidrug-resistant (MDR) Vibrio parahaemolyticus strains have become a great threat to public health. The purpose of this study was to investigate differences in biological characteristics and antimicrobial resistance gene (ARG) mutations of V. parahaemolyticus that displayed different levels of antimicrobial resistance. The susceptibility of 74 V. parahaemolyticus strains to 9 common antimicrobials was investigated, of which 88% were resistant to 3-4 antimicrobials and 3% to 5-7 antimicrobials. Interestingly, only 9% were resistant to 1-2 antimicrobials. The MDR strains possessed longer growth lag time than the non-MDR strains and displayed weaker swimming abilities. Whole genome sequencing was performed on strains VP41, VP44, 460, and 469 that were resistant to two to three classes of antimicrobials. ARGs were identified and compared with that of reference strain ATCC17802, and some important mutations were deduced. The Val189Ile mutation emerged in qnr gene of a single strain. Besides, the nonsynonymous mutations existed in four ARGs in different strains, including CatB (Pro165Ser, Gly208Asp), VmeA (Ile313Thr), VmeC (Glu329Ala), and VmeD (Asn205Ser). These results linked resistance gene mutations to enhance resistance in V. parahaemolyticus strains and provide a reference for more effective monitoring and prevention of V. parahaemolyticus infections.

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.

Analysis of Secreted Proteins and Potential Virulence via the ICEs-Mediated Pathway of the Foodborne Pathogen Vibrio parahaemolyticus

Vibrio parahaemolyticus uses bacterial secretion systems and integrative and conjugative elements (ICEs) to induce various diseases and to adapt to harsh environments, respectively. Information pertaining to the identity of secreted proteins and functional characterization of ICEs has been previously reported, but the relationship between these elements remains unclear. Herein we investigated secreted proteins of V. parahaemolyticus strains JHY20 and JHY20△ICE using two-dimensional gel electrophoresis and LC-MS/MS, which led to the identification of an ICE-associated secreted protein – dihydrolipoamide dehydrogenase (DLDH). Considering the data related to its physical and biochemical characterization, we predicted that DLDH is a novel immunogenic protein and associated with virulence in JHY20. Our findings indicate a potential relationship between ICE-associated transport and secreted proteins and shed light on the function of such transport mechanisms. We believe that our data should enhance our understanding of mobile genetic elements.

Influence of climatic factors on the temporal occurrence and distribution of total and pathogenic Vibrio parahaemolyticus in oyster culture environments in Taiwan

This study evaluated the occurrence and distribution of total and pathogenic V. parahaemolyticus in oyster culture environments in Taiwan. V. parahaemolyticus levels in oysters, seawater, and sediment were quantified using the most probable number (MPN) method combined with a qualitative polymerase chain reaction (PCR). Total V. parahaemolyticus was determined based on the presence or absence of tlh gene, whereas pathogenic V. parahaemolyticus was determined based on the detection of tdh and/or trh gene. The results showed that: 1) V. parahaemolyticus was detected in 93% of the collected samples, 2) the mean concentrations of total V. parahaemolyticus in oysters, seawater, and sediment were 4.1 log MPN/g, 2.1 log MPN/mL, and 4.2 log MPN/g, respectively, and 3) variations in the abundance of V. parahaemolyticus was significantly associated with sea surface temperature (SST). Findings in this study could be used to improve the accuracy of the risk assessment model for V. parahaemolyticus in oysters in Taiwan.

Prevalence, antibiotic susceptibility and characterization of Vibrio parahaemolyticus isolates in China

Vibrio parahaemolyticus is a marine and estuarine bacterium that poses a major threat to human health worldwide. In this study, from 2017 to 2019, we evaluated 900 food samples collected from China in 2017, with the aim of determining the incidence and features of V. parahaemolyticus in ready-to-eat (RTE) foods, shrimp and fish in China. The contamination rates in these were 3.67, 19.33 and 10.67%, respectively, and the prevalence of V. parahaemolyticus was higher in summer than in winter. In addition, 101 V. parahaemolyticus strains were isolated. Our results suggested that most of the isolates were resistant to aminoglycosides based on the antimicrobial resistance patterns of these aquatic product isolates against 14 antimicrobial agents. Furthermore, most of the isolates were multidrug-resistant. Serotyping showed that the isolates of the O2 serotype comprised the maximum proportion. Enterobacterial repetitive intergenic consensus sequence (ERIC)-PCR results indicated that the isolates (n = 101) could be classified into 12 clusters. There were 82 STs suggesting genetic variation and relatedness among these isolates. Our findings demonstrated the presence of V. parahaemolyticus in foods from Chinese retail markets and show that this methodology can be used for microbiological risk assessment in China.