Distribution, serological and molecular characterization of Vibrio parahaemolyticus from shellfish in the eastern coast of China

Antimicrobial resistance, virulence factors and phylogenetic profiles of Vibrio parahaemolyticus in the eastern coast of Shenzhen

Vibrio parahaemolyticus (V. parahaemolyticus) is a major food-borne pathogen which causes human gastroenteritis. Since the characteristics of V. parahaemolyticus remain unknown, 220 isolates selected from clinical and environmental samples in Dapeng of Shenzhen were tested for the presence of two hemolysin-expressing genes tdh and trh. Among 27 clinical isolates, 26 carrired the tdh gene, and the other one carried both tdh and trh genes, however neither genes were detected in environmental isolates. Meanwhile, antimicrobial susceptibility profiles revealed the isolates with high frequency of resistance to ampicillin (77.73%) and colistin (71.82%) and medium to streptomycin (57.27%). Genetically, by whole genome sequencing (WGS), comparative genomics studies was performed on isolates from various districts and GenBank. Data analysis showed that antimicrobial resistance genes (ARGs) blaCARB, tet(34) and tet(35) were harbored in all genomes and other ARGs was absent in the genomes of 27 clinical isolates. Besides, little regional difference was observed. As for virulence factors, MAM7, T3SS1, T3SS1 secret effector, T3SS2, T3SS2 secret effector, and VpadF were carried by most isolates. Two isolates from other districts were tdh gene positive which clustered with clinical isolates from Dapeng in the same clade, indicating close genetic distance. This study revealed the widely distribution of V. parahaemolyticus in Shenzhen and the diverse ARGs and virulence genes it carried. Furthermore, pathways that pathogen disseminated through were discussed.

Serodiversity, antibiotic resistance, and virulence genes of Vibrio parahaemolyticus in oysters collected in coastal areas of northwestern Mexico between 2012 and 2020

This study aimed to determine the prevalence of V. parahaemolyticus in oysters from the northwestern coast of Mexico and to identify the serotypes, virulence factors, and antibiotic resistance of the strains. Oyster samples were collected from 2012 to 2020 from the northwest coast of Mexico; biochemical and molecular methods were used to identify V. parahaemolyticus from oysters; antiserum reaction to determine V. parahaemolyticus serotypes, and PCR assays were performed to identify pathogenic (tdh and/or trh) or pandemic (toxRS/new, and/or orf8) strains and antibiotic resistance testing. A total of 441 oyster samples were collected and tested for V. parahaemolyticus. Forty-seven percent of oyster samples were positive for V. parahaemolyticus. Ten different O serogroups and 72 serovars were identified, predominantly serotype O1:KUT with 22.2% and OUT:KUT with 17.3%. Twenty new serotypes that had not been previously reported in our region were identified. We detected 4.3% of pathogenic clones but no pandemic strains. About 73.5% of strains were resistant to at least one antibiotic, mainly ampicillin and ciprofloxacin; 25% were multi-drug resistant. In conclusion, the pathogenic strains in oysters and antibiotic resistance are of public health concern, as the potential for outbreaks throughout northwestern Mexico is well established.

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

Quantitative Risk Assessment of Vibrio parahaemolyticus Toxi Infection Associated with the Consumption of Roasted Shrimp (Penaeus monodon)

In this study, a risk assessment on Vibrio parahaemolyticus infections was carried out in order to estimate the likelihood of gastroenteritis for Cameroonians after consumption of roasted shrimp (Penaeus monodon). The Codex Alimentarius Commission framework was used in this study. Based on the distribution of total V. parahaemolyticus in shrimp and literature information indicating that nonhaemolysing carrier strains could be pathogenic to humans, the cooking, and consumption patterns, the daily exposure level generated in this study, and the dose-response model from other studies, the infectious risk was evaluated and quantified by the Monte Carlo simulation. This simulation was realized based on 10,000 iterations using the Model Risk software, version 4.0, in combination with Microsoft Excel. To better quantify the exposure of consumers and the resulting risk of infection, several scenarios reflecting the minimal, average, and maximal exposures were undertaken. According to the results, the 90% confidence intervals for minimum and maximum exposures ranged from 15 to 24 colony-forming units per day (cells/day) and from 160 to 228 cells/day, respectively. Based on the modal scenario, 90% of the population consuming this shrimp is exposed to V. parahaemolyticus loads ranging from 74 to 110 cells/day, indicating a risk of infection ranging from 1.2 to 1.8 cases per million of consumption. The estimated number of annual disease cases based on annual production is between 1 and 10 cases. This reflects a relatively low risk of infection for roasted shrimp. Good hygiene practices during handling, cooking, and storage may help reduce the actual risk.

Vibrio alginolyticus Survives From Ofloxacin Stress by Metabolic Adjustment

Antibiotic-resistant Vibrio alginolyticus becomes a worldwide challenge threatening both human health and food safety. The approach in managing such infection is largely absent, despite the fact that the mechanisms of antibiotic resistance have been extensively investigated. Metabolic modulation has been documented to be a novel approach in improving antibiotic efficacy. In this study, we characterize the metabolic signature of V. alginolyticus exposed to 0.3 or 0.5 μg/ml of ofloxacin (OFX). By profiling the metabolome, we find that bacteria treated by the two different concentrations of OFX generate different metabolic signatures. While a part of these metabolites was shared by both groups, the other metabolites represent their own signatures. The pathway enrichment analysis demonstrates that the pyruvate cycle is disrupted in the bacteria treated by the 0.3 μg/ml OFX as compared to those by the 0.5 μg/ml. Importantly, the disruption of pyruvate cycle confers the capability of bacteria to survive under 0.5 μg/ml of antibiotic stress. Further analysis identifies that the fatty acid biosynthesis is elevated in bacteria treated by 0.3 μg/ml OFX, and inhibition on fatty acid completely prevents the bacteria from survival even under such dose of antibiotic stress. Our study suggests that bacteria adapt to antibiotic stress by modulating the metabolic flux for survival, which could be targeted to increase antibiotic efficacy.

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.

Combination of Direct Viable Count and Fluorescent In Situ Hybridization (DVC-FISH) as a Potential Method for Identifying Viable Vibrio parahaemolyticus in Oysters and Mussels

Vibrio parahaemolyticus is a human food-borne pathogen with the ability to enter the food chain. It is able to acquire a viable, non-cultivable state (VBNC), which is not detected by traditional methods. The combination of the direct viable count method and a fluorescent in situ hybridization technique (DVC-FISH) makes it possible to detect microorganisms that can present VBNC forms in complex samples The optimization of the in vitro DVC-FISH technique for V. parahaemolyticus was carried out. The selected antibiotic was ciprofloxacin at a concentration of 0.75 μg/mL with an incubation time in DVC broth of 5 h. The DVC-FISH technique and the traditional plate culture were applied to detect and quantify the viable cells of the affected pathogen in artificially contaminated food matrices at different temperatures. The results obtained showed that low temperatures produced an important logarithmic decrease of V. parahaemolyticus, while at 22 °C, it proliferated rapidly. The DVC-FISH technique proved to be a useful tool for the detection and quantification of V. parahaemolyticus in the two seafood matrices of oysters and mussels. This is the first study in which this technique has been developed to detect viable cells for this microorganism.

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.

Prevalence, antibiogram and virulence characterization of Vibrio isolates from fish and shellfish in Egypt: a possible zoonotic hazard to humans

AIMS

Infection of seafood with pathogenic species of the genus Vibrio causes human food-borne illnesses. This study was executed to examine the antimicrobial resistance phenotypes, biofilm-forming capability and virulence-associated genes of Vibrio from fish and shellfishes.

METHODS AND RESULTS

Three hundred fresh water and marine fish and shellfish samples were collected from wet markets and supermarkets in Mansoura, Egypt. Bacteriological examination and PCR amplification identified 92 Vibrio spp., including 42 Vibrio parahaemolyticus and 50 Vibrio alginolyticus isolates from the examined fish and shellfish (infection rate: 30·67%). However, V. vulnificus was not found in this study. Vibrio spp. exhibited variable frequencies of antimicrobial resistance with higher percentages to ampicillin and penicillin. Multidrug resistance (MDR) was detected in 69·04 and 38% of V. parahaemolyticus and V. alginolyticus respectively. PCR testing of virulence genes, tdh, trh and tlh revealed the presence of tlh and trh in 100 and 11·9% of V. parahaemolyticus isolates respectively and none of V. alginolyticus carried any of these genes. Biofilm-forming capability was displayed by 76% of V. parahaemolyticus and 73·8% of V. alginolyticus isolates. Both V. parahaemolyticus and V. alginolyticus showed nonsignificant weak positive correlations (r < 0·4) between antimicrobial pairs belonging to different classes; however, a significant positive correlation (P <0·05) between trh and resistance to erythromycin (r = 0·45) and imipenem (r = 0·38) was only identified in V. parahaemolyticus.

CONCLUSIONS

This study reports the existence of MDR strains of V. parahaemolyticus and V. alginolyticus from the common types of fishes and shellfishes in Egypt. Furthermore, the presence of virulence genes in these isolates and the ability to produce a biofilm in vitro pose potential health hazards to consumers.

SIGNIFICANCE AND IMPACT OF THE STUDY

Frequent monitoring of seafood for the presence of Vibrio spp. and their antimicrobial susceptibility, virulence determinants and biofilm-forming capability is important for assessing the risk posed by these organisms to the public and for improving food safety.

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.

Food-Borne Vibrio parahaemolyticus in China: Prevalence, Antibiotic Susceptibility, and Genetic Characterization

Vibrio parahaemolyticus is a marine and estuarine bacterium that leads to damage of aquatic industry by foodborne outbreaks and possesses an enormous threat to food safety as well as human health worldwide. In the current study, we investigated 905 food samples (ready-to-eat foods, fish, and shrimp) from 15 provinces in China, and aimed to determine prevalence, biological characteristics and genetic diversity of presumptive V. parahaemolyticus isolates. Firstly, 14.17% of 240 fish samples, 15.34% of 365 shrimp samples and 3.67% of 300 RTE food samples were positive for potential V. parahaemolyticus. Secondly, 69 food samples (14.87%) collected in summer were positive for target isolates, while the rate of positive sample of 441 food samples in winter reached 7.26%. Thirdly, we purified 202 V. parahaemolyticus strains for further research. And antimicrobial susceptibility results of strains tested revealed that the highest resistance rate was observed for ampicillin (79.20%). At the same time, 148 (73.27%) of all isolates were classified and defined as multi-drug resistant foodborne bacteria. The results of PCR assay showed that the isolates being positive for the tdh, trh or both genes, were up to 9.90%, 19.80% or 3.96%. Besides, multiplex PCR test showed that the isolates carrying O2 serogroup were the most prevalent. Furthermore, sequence types (STs) of 108 isolates were obtained via multi-locus sequence typing. Not only 82 STs were detected, but also 41 of which were updated in the MLST database. Thus, our findings significantly demonstrated the high contamination rates of V. parahaemolyticus in fish and shrimp and it may possess potential threat for consumer health. We also provided up-to-date dissemination of antibiotic-resistant V. parahaemolyticus which is important to ensure the high efficacy in the treatment of human and aquatic products infections. Lastly, with the identification of 82 STs including 41 novel STs, this study significantly revealed the high genetic diversity among V. parahaemolyticus. All of our research improved our understanding on microbiological risk assessment in ready-to-eat foods, fish, and shrimp.

Heavy metal and antibiotic co-resistance in Vibrio parahaemolyticus isolated from shellfish

Vibrio parahaemolyticus is a major gastroenteritis-causing pathogen in Korea. Recent studies have reported that heavy metal and antimicrobial resistance in bacteria are related. In this study, we investigated heavy metal and antimicrobial resistance in wild strains of V. parahaemolyticus. First, we isolated and characterized 38 V. parahaemolyticus strains (toxR-positive) from shellfish collected from the West Sea of Korea between May and November 2018. Antibiotic and heavy metal resistance in the 38 strains were tested by disk diffusion assay and broth dilution assay, respectively. Then, we selected seven strains that showed resistance to cobalt (Co²⁺) and copper (Cu²⁺), to examine the relationship between heavy metal resistance and antimicrobial resistance. After heavy metal (Co²⁺ and Cu²⁺) pretreatment, the seven strains exhibited increased resistance to kanamycin, streptomycin, tetracycline, and gentamycin. Likewise, antimicrobial pretreatment resulted in increased heavy metal tolerance.

Isolation, Molecular Characterization and Antibiotic Susceptibility Pattern of Vibrio parahaemolyticus from Aquatic Products in the Southern Fujian Coast, China

Vibrio parahaemolyticus is a major gastroenteritis-causing pathogen in many Asian countries. Antimicrobial resistance in V. parahaemolyticus has been recognized as a critical threat to food safety. In this study, we determined the prevalence and incidence of antimicrobial resistance in V. parahaemolyticus in the southern Fujian coast, China. A total of 62 isolates were confirmed in retail aquatic products from June to October of 2018. The serotype O3:K6 strains, the virulence genes tdh and trh, antibiotic susceptibility and molecular typing were investigated. Then plasmid profiling analysis and curing experiment were performed for multidrug-resistant strains. The results showed that the total occurrence of V. parahaemolyticus was 31% out of 200 samples. Five strains (8.1%) out of 62 isolates were identified as the V. parahaemolyticus O3:K6 pandemic clone. A large majority of isolates exhibited higher resistance to penicillin (77.4%), oxacillin (71%), ampicillin (66.1%) and vancomycin (59.7%). Seventy-one percent (44/62) of the isolates exhibited multiple antimicrobial resistance. All 62 isolates were grouped into 7 clusters by randomly amplified polymorphic DNA, and most of the isolates (80.6%) were distributed within cluster A. Plasmids were detected in approximately 75% of the isolates, and seven different profiles were observed. Seventy-six percent (25/33) of the isolates carrying the plasmids were eliminated by 0.006% SDS incubated at 42°C, a sublethal condition. The occurrence of multidrug-resistant strains could be an indication of the excessive use of antibiotics in aquaculture farming. The rational use of antimicrobial agents and the surveillance of antibiotic administration may reduce the acquisition of resistance by microorganisms in aquatic ecosystems.

Metabolic modulation of redox state confounds fish survival against Vibrio alginolyticus infection

Vibrio alginolyticus threatens both humans and marine animals, but hosts respond to V. alginolyticus infection is not fully understood. Here, functional metabolomics was adopted to investigate the metabolic differences between the dying and surviving zebrafish upon V. alginolyticus infection. Tryptophan was identified as the most crucial metabolite, whose abundance was decreased in the dying group but increased in the survival group as compared to control group without infection. Concurrently, the dying zebrafish displayed excessive immune response and produced higher level of reactive oxygen species (ROS). Interestingly, exogenous tryptophan reverted dying rate through metabolome re‐programming, thereby enhancing the survival from V. alginolyticus infection. It is preceded by the following mechanism: tryptophan fluxed into the glycolysis and tricarboxylic acid cycle (TCA cycle), promoted adenosine triphosphate (ATP) production and further increased the generation of NADPH. Meanwhile, tryptophan decreased NADPH oxidation. These together ameliorate ROS, key molecules in excessive immune response. This is further supported by the event that the inhibition of pyruvate metabolism and TCA cycle by inhibitors decreased D. reiro survival. Thus, our data indicate that tryptophan is a key metabolite for the host to fight against V. alginolyticus infection, representing an alternative strategy to treat bacterial infection in an antibiotic‐independent way.

Antibiotic and heavy-metal resistance of Vibrio parahaemolyticus isolated from oysters in Korea

Vibrio parahaemolyticus, found frequently in oysters and other seafoods, is the most prevalent gastroenteritis-causing pathogen in Korea and other Asian countries. It is associated exclusively with the consumption of raw or improperly cooked contaminated seafood, especially oysters. In this study, we isolated and characterized 59 V. parahaemolyticus strains (toxR-positive) from May to October 2016 in shellfish-harvesting areas off the west coast of Korea. The results revealed that none of the isolates contained the tdh and trh toxicity genes. The multiple antibiotic resistance (MAR) value of most isolates was 0.32, but it was as high as 0.69 in one isolate strain. Moreover, when resistance to heavy metals was examined, the majority of the isolates displayed resistance to Ba²⁺ (98.3%), Co³⁺ (28.8%), Cd²⁺ (16.9%), and Cu²⁺ (13.6%). Interestingly our data revealed that tolerance to heavy metals was prevalent in the V. parahaemolyticus strains with more than two antibiotic resistance phenotypes.

Giant Gold Nanowire Vesicle-Based Colorimetric and SERS Dual-Mode Immunosensor for Ultrasensitive Detection of Vibrio parahemolyticus

Conventional methods for the detection of Vibrio parahemolyticus (VP) usually need tedious, labor-intensive processes, and have low sensitivity, which further limits their practical applications. Herein, we developed a simple and efficient colorimetry and surface-enhanced Raman scattering (SERS) dual-mode immunosensor for sensitive detection of VP, by employing giant Au vesicles with anchored tiny gold nanowires (AuNW) as a smart probe. Due to the larger specific surface and special hollow structure of giant Au vesicles, silver staining would easily lead to vivid color change for colorimetric analysis and further amplify SERS signals. The t-test was further used to determine if two sets of data from colorimetry and SERS were significantly different from each other. The result shows that there was no significant difference between data from the two methods. Two sets of data can mutually validate each other and avoid false positive and negative detection. The designed colorimetry-SERS dual-mode sensor would be very promising in various applications such as food safety inspection, personal healthcare, and on-site environmental monitoring.

Prevalence, Antibiotic Susceptibility and Diversity of Vibrio parahaemolyticus Isolates in Seafood from South China

Vibrio parahaemolyticus is a leading cause of foodborne infections in China and a threat to human health worldwide. The main objective of this study is to determine the prevalence and characteristic of V. parahaemolyticus isolates in fish, oyster and shrimp samples from the South China domestic consumer market. To accomplish this, we examined 504 seafood samples from 11 provinces of China. The prevalence rates were 9.38, 30.36, and 25.60%, respectively. In summer (33.33%), the prevalence of V. parahaemolyticus was more common than that detected in the winter (14.01%). In addition, we identified 98 V. parahaemolyticus strains. The antimicrobial resistance trends of our seafood isolates to 15 antimicrobial agents revealed that major isolates were resistant to ampicillin (79.59%). Furthermore, 68.38% of the isolates were identified as being multidrug resistance. The prevalence of tdh or trh genes among the isolates was 8.16 and 12.24%, respectively. ERIC-PCR and multilocus sequence typing (MLST) results enabled classification of the isolates (n = 98) into different clusters, revealing genetic variation and relatedness among the isolates. Thus, our findings demonstrate the prevalence of V. parahaemolyticus in a variety of common seafood consumed domestically in China and provides insights into the dissemination of antibiotic-resistant strains, which should improve our microbiological risk assessment knowledge associated with V. parahaemolyticus in seafoods.

Distribution and antimicrobial susceptibility of Vibrio species associated with zooplankton in coastal area of Korea

Vibrio parahaemolyticus and V. vulnificus are the most common pathogens causing seafood-borne illnesses in Korea. This study determines the abundance and antimicrobial resistance of pathogenic Vibrio species in seawater and zooplankton samples from the Geoje Island coast in Korea, which is an important area for coastal fisheries, the fishing industry, and tourism. The two Vibrio species were detected more in mesozooplankton samples than in seawater samples. V. parahaemolyticus isolates showed greater resistance than those of V. vulnificus for antimicrobials. Of V. parahaemolyticus isolates, 93.3% exhibited resistance to three or more antimicrobial agents. Conversely, more than 80% of V. vulnificus isolates showed susceptibility to all antimicrobials examined, with the exception of rifampicin. Our findings show that strong antimicrobial resistance of V. parahaemolyticus in the surveyed area was exposed to conventionally used antibiotics, therefore necessitating proper surveillance programs for the monitoring of antimicrobial resistance patterns in seawater bodies and aquatic animals.

Antimicrobial susceptibility of Vibrio alginolyticus isolated from oyster in Korea

Pathogenic Vibrio alginolyticus, a cause of severe infection in shellfish, as well as in humans, has been found at high frequency around all coastal areas of Korea. The aim of this study was to determine the occurrence of V. alginolyticus, to identify the strains isolated from oysters in West Sea, and to investigate their antimicrobial resistance profiles. Biochemical analyses of the 90 initially recovered presumptive V. alginolyticus colonies indicated that 16 isolates were V. alginolyticus. PCR analysis to detect the presence of the gyrB gene confirmed that 15 (93.8 %) of the 16 isolates were V. alginolyticus. These 15 isolates had the following profiles of resistance against 16 antibiotics: all isolates were resistant to ampicillin and vancomycin, and 26.7 % of the isolates exhibited resistance to cephalothin. A large number of isolates showed intermediate resistance to erythromycin (100 %) and rifampin (73.3 %). Five (33.3 %) of the V. alginolyticus isolates demonstrated multiple resistance to at least three antimicrobials.

Population Relationship of Vibrio parahaemolyticus Isolates Derived from Aquaculture Ponds, a Seafood Market, Restaurants, and Clinical Samples

To study the relationship between environmental and clinical populations of Vibrio parahaemolyticus, we collected in total 86 isolates from Southern China during one and a half years. Sixty-eight isolates were recovered from aquaculture ponds, a seafood market, and restaurants, and 18 isolates were recovered from clinical samples. Virulence gene analysis revealed that 25 isolates (14 clinical and 11 environmental) tested positive for tdh, but only 4 carried trh. Interestingly, none of the tdh(+) environmental isolates was recovered from ponds. Both environmental and clinical tdh(+) isolates, except for one clinical isolate, harbor type III secretion system 2α (T3SS2α) and T3SS2β-related genes, including vopB2α, which was previously suggested to be absent from environmental strains. More than 70% of clinical isolates carried the pandemic marker of new toxRS (GS-PCR(+)), which was not present in the environmental isolates. Pulsed-field gel electrophoresis and multilocus sequence typing analysis showed a high degree of genetic diversity within the environmental isolates. In contrast, the clinical population formed a tight cluster that differed from the environmental isolates. These findings suggest that the pandemic strains of V. parahaemolyticus may not directly originate from marine animals. Rather the environments where they are maintained could serve as reservoirs for toxigenic, but not pandemic strains. These environments provide an ideal place for generation of new toxigenic strains through DNA exchange, which was revealed by extensive recombination events in recA sequences of the environmental isolates.

Prevalence, Molecular Characterization, and Antibiotic Susceptibility of Vibrio parahaemolyticus from Ready-to-Eat Foods in China

Vibrio parahaemolyticus is the leading cause of foodborne outbreaks, particularly outbreaks associated with consumption of fish and shellfish, and represents a major threat to human health worldwide. This bacterium harbors two main virulence factors: the thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH). Additionally, various serotypes have been identified. The extensive use of antibiotics is a contributing factor to the increasing incidence of antimicrobial-resistant V. parahaemolyticus. In the current study, we aimed to determine the incidence and features of V. parahaemolyticus in ready-to-eat (RTE) foods in China. We found 39 V. parahaemolyticus strains on Chinese RTE foods through investigation of 511 RTE foods samples from 24 cities in China. All isolates were analyzed for the presence of tdh and trh gene by PCR, serotyping was performed using multiplex PCR, antibiotic susceptibility analysis was carried out using the disk diffusion method, and molecular typing was performed using enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) typing and multilocus sequence typing (MLST). The results showed that none of the isolates were positive for tdh and trh. Most of the isolates (33.3%) were serotype O2. Antimicrobial susceptibility results indicated that most strains were resistant to streptomycin (89.7%), cefazolin (51.3%), and ampicillin (51.3%). The isolates were grouped into five clusters by ERIC-PCR and four clusters by MLST. We updated 10 novel loci and 33 sequence types (STs) in the MLST database. Thus, our findings demonstrated the presence of V. parahaemolyticus in Chinese RTE foods, provided insights into the dissemination of antibiotic-resistant strains, and improved our knowledge of methods of microbiological risk assessment in RTE foods.

Incidence and prevalence of Vibrio parahaemolyticus in seafood: a systematic review and meta-analysis

Vibrio parahaemolyticus is an important seafood borne human pathogen worldwide due to it occurrence, prevalence and ability to cause gastrointestinal infections. This current study aim at investigating the incidence and prevalence of V. parahaemolyticus in seafood using systematic review-meta-analysis by exploring heterogeneity among primary studies. A comprehensive systematic review and meta-analysis of peer reviewed primary studies reported between 2003 and 2015 for the occurrence and prevalence of V. parahaemolyticus in seafood was conducted using “isolation”, “detection”, “prevalence”, “incidence”, “occurrence” or “enumeration” and V. parahaemolyticus as search algorithms in Web of Science (Science Direct) and ProQuest of electronic bibliographic databases. Data extracted from the primary studies were then analyzed with fixed effect meta-analysis model for effect rate to explore heterogeneity between the primary studies. Publication bias was evaluated using funnel plot. A total of 10,819 articles were retrieved from the data bases of which 48 studies met inclusion criteria. V. parahaemolyticus could only be isolated from 2761 (47.5 %) samples of 5811 seafood investigated. The result of this study shows that incidence of V. parahaemolyticus was more prevalent in oysters with overall prevalence rate of 63.4 % (95 % CI 0.592–0.674) than other seafood. Overall prevalence rate of clams was 52.9 % (95 % CI 0.490–0.568); fish 51.0 % (95 % CI 0.476–0.544); shrimps 48.3 % (95 % CI 0.454–0.512) and mussels, scallop and periwinkle: 28.0 % (95 % CI 0.255–0.307). High heterogeneity (p value <0.001; I² = 95.291) was observed mussel compared to oysters (I² = 91.024). It could be observed from this study that oysters harbor V. parahaemolyticus based on the prevalence rate than other seafood investigated. The occurrence and prevalence of V. parahaemolyticus is of public health importance, hence, more studies involving seafood such as mussels need to be investigated.

Prevalence, characterization, and antibiotic susceptibility of Vibrio parahaemolyticus isolated from retail aquatic products in North China

Background

Vibrio parahaemolyticus is a major foodborne pathogen, particularly in Asian countries. Increased occurrence of outbreaks of V. parahaemolyticus gastroenteritis in China indicates the need to evaluation of the prevalence of this pathogenic species. V. parahaemolyticus distribution in shellfish from the eastern coast of China has been reported previously. However, to date, the prevalence of V. parahaemolyticus in retail aquatic products in North China has not been determined. To investigate the prevalence of V. parahaemolyticus in aquatic products in North China, 260 aquatic product samples were obtained from retail markets in 6 provinces of North China from November to December in 2012 and July to August in 2013.

Results

V. parahaemolyticus was detected in 94 (36.2 %) of the samples by the most probable number method. The density of V. parahaemolyticus ranged from 1.50 to 1100 MPN/g. V. parahaemolyticus was detected at a rate of 50.0 % and 22.7 % in summer and in winter, respectively. The density of V. parahaemolyticus was significantly higher in summer than in winter, with mean levels of 16.5 MPN/g and 5.0 MPN/g, respectively. Among 145 V. parahaemolyticus isolates examined, none of the isolates possessed tdh and trh. In multiplex PCR-based O-antigen serotyping of these 145 isolates, all serotypes, other than O6, O7, and O9, were detected, and serotype O2 was found to be the most prevalent (detected in 54 isolates). The 145 isolates were grouped into 7 clusters by enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) at a similarity coefficient of 0.66. The antimicrobial resistance patterns of these 145 isolates to 12 antimicrobial agents revealed that most of the isolates were resistant to streptomycin (86.2 %), while fewer were resistant to ampicillin (49.6 %), cefazolin (43.5 %), cephalothin (35.9 %), and kanamycin (22.1 %). All of the examined isolates were susceptible to azithromycin and chloramphenicol.

Conclusions

The findings of this study will help in defining appropriate monitoring programs, understanding of the dissemination of antibiotic resistant strains, and providing information for the assessment of exposure to this microorganism at the consumption level.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0650-6) contains supplementary material, which is available to authorized users.

Prevalence and antimicrobial susceptibility of Vibrio parahaemolyticus isolated from oysters in Korea

Vibrio parahaemolyticus is the most prevalent gastroenteritis-causing pathogen in Korea and in some other Asian countries. It is frequently found in oysters and other seafood. This study monitored changes in the prevalence of V. parahaemolyticus and environmental parameters in oyster aquaculture environments in Korea. From June to October 2014, we tested oysters (Crassostrea gigas) from shellfish-harvesting areas off the west coast of Korea. These 71 isolates were the sum of 16 (22.5%), 19 (26.8%), 23 (32.4%), and 13 (18.3%) isolates collected in July, August, September, and October, respectively. These 71 isolates had the following profiles of resistance against 16 antibiotics: all isolates were resistant to ampicillin and vancomycin, and 52.2, 50.7, and 50.7% of isolates exhibited resistance to cephalothin, rifampin, and streptomycin, respectively. PCR analysis for the presence of the species-specific toxR gene confirmed that 38 (53.5%) of the total 71 isolated strains were positive for V. parahaemolyticus. In PCR analysis for virulence of V. parahaemolyticus, of the 71 isolates tested in the present study, only 38 (53.5%) were positive for the trh virulence gene and 71 (100%) was negative for the tdh virulence gene.

Occurrence and Antibiotic Resistance of Vibrio parahaemolyticus from Shellfish in Selangor, Malaysia

High consumer demand for shellfish has led to the need for large-scale, reliable shellfish supply through aquaculture or shellfish farming. However, bacterial infections which can spread rapidly among shellfish poses a major threat to this industry. Shellfish farmers therefore often resort to extensive use of antibiotics, both prophylactically and therapeutically, in order to protect their stocks. The extensive use of antibiotics in aquaculture has been postulated to represent a major contributing factor in the rising incidence of antimicrobial resistant pathogenic bacteria in shellfish. This study aimed to investigate the incidence of pathogenic Vibrio parahaemolyticus and determine the antibiotic resistance profile as well as to perform plasmid curing in order to determine the antibiotic resistance mediation. Based on colony morphology, all 450 samples tested were positive for Vibrio sp; however, tox-R assay showed that only 44.4% (200/450) of these were V. parahaemolyticus. Out of these 200 samples, 6.5% (13/200) were trh-positive while none were tdh-positive. Antibiotic resistance was determined for all V. parahaemolyticus identified against 14 commonly used antibiotics and the multiple antibiotic resistance index (MAR) was calculated. The isolates demonstrated high resistance to several antibiotics tested- including second and third-line antibiotics- with 88% resistant to ampicillin, 81% to amikacin,70.5% to kanamycin, 73% to cefotaxime, and 51.5% to ceftazidime. The MAR index ranged from 0.00 to 0.79 with the majority of samples having an index of 0.36 (resistant to five antibiotics). Among the 13 trh-positive strains, almost 70% (9/13) demonstrated resistance to 4 or more antibiotics. Plasmid profiling for all V. parahaemolyticus isolates revealed that 86.5% (173/200) contained plasmids - ranging from 1 to 7 plasmids with DNA band sizes ranging from 1.2 kb to greater than 10 kb. 6/13 of the pathogenic V. pathogenic strains contained plasmid. After plasmid curing, the plasmid containing pathogenic strains isolated in our study have chromosomally mediated ampicillin resistance while the remaining resistance phenotypes are plasmid mediated. Overall, our results indicate that while the incidence of pathogenic V. parahaemolyticus in shellfish in Selangor still appears to be at relatively reassuring levels, antibiotic resistance is a real concern and warrants ongoing surveillance.