• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.543-551
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• 1985

A new class of polyhydrazones has been synthesized by the solution polycondensation from equimolecular amounts of aromatic dialdehydes such as para, meta, ortho-phthal aldehyde, 5,5'-methylene-bis-salicyl aldehyde (PPTA, MPTA, OPTA, MBSA) and dihydrazides, 5,5'-methylene-bis-salicylic dihydrazide (MBSDH), terephthalic dihydrazide (TDH), sebacic dihydrazide (SDH) in DMF-$CH_3COOH$ solution. The solubility characteristics, spectral, and thermal properties of the synthesized polyhydrazones and their metal chelates were also studied. These polyhydrazones and their metal chelates except the polyhydrazone prepared from OPTA-MBSDH were generally insoluble in common organic solvents. The thermogravimetric analysis of polyhydrazones showed 10% weight losses at 250∼350$^{\circ}$C and residual weight at 500$^{\circ}$C were 32.5∼62.5%. The decomposition temperature of higher relatively, and the metal chelates decrease in the following orders; Zn(II)-IIa > Ni(II)-IIa > Co(II)-IIa > Cu(II)-IIa.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.248-254
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• 2018

To assess the risk of V. parahaemolyticus infection caused by consumption of raw oysters in Korea, contamination levels during the retail-to-table route of oysters was modeled to predict V. parahaemolyticus growth based on temperature and time. The consumed amount data of the KNHANES and the standard recipe of RDA were applied. A consumption scenario for exposure assessment was developed and combined with a Beta-Poisson dose-response model. The estimated probability of illness from consumption of pathogenic V. parahaemolyticus in raw oysters during three separate months (April, October, and November) was $5.71{\times}10^{-5}$ (within the 5th and 95th percentile ranges of $2.71{\times}10^{-8}$ to $1.03{\times}10^{-4}$). The results of the quantitative microbial-risk assessment indicated that the major factors affecting the probability of illness were the initial contamination level at the retailer, the consumed amount, the prevalence of pathogenic strains [tdh or trh genes], and exposure temperature and time.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.3
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• pp.220-226
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• 2014

Sixty-seven Vibrio parahaemolyticus isolates from surface seawater from the Wando area, on the southern coast of Korea, were analyzed for their susceptibility to 15 different antimicrobials and the presence of virulence genes. According to the disk diffusion susceptibility test, all of the strains studied were resistant to ampicillin and oxacillin, while decreasing percentages were resistant to vancomycin (64.2%), streptomycin (56.7%), amikacin (31.3%), kanamycin (22.3%), cephalothin (20.9%), erythromycin (10.4%), ciprofloxacin (4.5%), and tetracycline (3.0%). All of the strains were susceptible to five antimicrobials: chloramphenicol, gentamycin, nalidixic acid, sulfamethoxazole/trimethoprim, and trimethoprim. Fifty-nine isolates (88.1%) were resistant to three or more classes of antimicrobial and defined as multidrug resistant, and two strains were resistant to seven antimicrobial agents. The minimum inhibitory concentration (MIC) of the 67 V. parahaemolyticus isolates to ampicillin and oxacillin ranged from 512-2,048 and $64-512{\mu}g/mL$, respectively. All 67 isolates were also examined for the presence of the tdh and trh virulence genes using the polymerase chain reaction (PCR). However, no isolates possessed either tdh or trh. The VPA0477 (${\beta}$-lactamase) gene, present in all of the tested strains, was validated as a new specific marker gene in PCR assays for the accurate detection and identification of V. parahaemolyticus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.4
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• pp.460-466
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• 2016

From 2013 through 2015, we investigated the contamination status and antimicrobial resistance patterns of pathogenic Vibrio parahaemolyticus in commercially valuable seawater and shellfish (Oyster Crassostrea gigas, short-neck clam Venerupis philippinarum, ark shell Scapharca broughtonii and mussel Mytilus galloprovinciallis) from the southern coast of Korea. The detection rate of V. parahaemolyticus was highest in short-neck clams (23.7%), followed by ark shells (19.2%), oysters (15.9%), mussels (13.6%), and seawater (8.6%). The following percentages of PCR assays of shellfish were positive for the thermostable direct hemolysin-related hemolysin gene (trh) : oysters (12.8%), short-neck clams(11.8%), and ark shells (3.4%). Similar assays for the thermostable direct hemolysin gene (tdh) resulted in positive results for short-neck clams (5.9%) and ark shells (3.4%). Antimicrobial resistance was present in 100% of 8 tdh (+) and 2 trh (+) V. parahaemolyticus isolates challenged with ampicillin. However, all pathogenic V. parahaemolyticus were sensitive to 14 other antibiotics. To ensure the safety of shellfish consumption, the continuous monitoring of the prevalence and distribution of virulence factors of V. parahaemolyticus in shellfish farms is needed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.582-588
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• 2016

Seventy-nine Vibrio parahaemolyticus isolates from surface seawater from Gomso Bay, west coast of Korea, were analyzed for the presence of virulence genes and their susceptibility to 30 different antimicrobials. All 79 isolates were examined for the presence of two virulence genes (tdh or trh) using polymerase chain reaction (PCR); however, no isolates possessed either the tdh or trh gene. According to a disk diffusion susceptibility test, all of the strains studied were resistant to oxacillin, penicillin, and vancomycin, followed by ticarcillin (97.5%), ampicillin (96.2%), clindamycin (86.1%), erythromycin (10.1%), streptomycin (7.6%), cefoxitin (6.3%), amikacin (2.5%), and cephalothin (2.5%). However, all of the strains were susceptible to 19 other antimicrobials including cefepime, cefotaxime, chloramphenicol, gentamycin, nalidixic acid, sulfamethoxazole/trimethoprim, and trimethoprim. All 79 isolates (100%) were resistant to four or more classes of antimicrobials, and two strains exhibited resistance to eight antimicrobial agents. The average minimum inhibitory concentrations (MICs) for V. parahaemolyticus for ampicillin, penicillin, ticarcillin, and vacomycin were 946.5, 1,305.9, 1,032.3, and 45.0 µg/mL, respectively.

• Fisheries and Aquatic Sciences
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• v.21 no.2
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• pp.3.1-3.10
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• 2018

Background: Vibrio parahaemolyticus is one of the most common causes of seafood-borne illnesses in Korea, either directly or indirectly, by consuming infected seafood. Many studies have demonstrated the antibiotic susceptibility profile of V. parahaemolyticus. This strain has developed multiple antibiotic resistance, which has raised serious public health and economic concerns. This article reviews the food-borne outbreaks, distributions, virulence, and antibiotic resistance profiles of V. parahaemolyticus in Korea during 2003-2016. Main body: V. parahaemolyticus infections appeared to be seasonally dependent, because 69.7% of patient infections occurred in both August and September during 2003-2016. In addition, the occurrence of V. parahaemolyticus in marine environments varies seasonally but is particularly high in July, August, and September. V. parahaemolyticus isolated from aquaculture sources on the Korean coast varied in association with virulence genes, some did not possess either the tdh (thermostable direct hemolysin) or trh (tdh-related hemolysin) genes, and a few were positive for only the trh gene or both genes. The high percentage of ampicillin resistance against V. parahaemolyticus in the aquatic environment suggests that ampicillin cannot be used to effectively treat infections caused by this organism. Short conclusion: This study shows that the observed high percentage of multiple antibiotic resistance to V. parahaemolyticus is due to conventionally used antibiotics. Therefore, monitoring the antimicrobial resistance patterns at a national level and other solutions are needed to control aquaculture infections, ensure seafood safety, and avoid threats to public health caused by massive misuse of antibiotics.

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.63-68
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• 2022

The purpose of this study is to investigate the distribution of toxin genes and antimicrobial resistance of Vibrio parahaemolyticus isolated from seafood in Gwangju. A total of 335 seafood, including 163 shellfish, 97 fish, and 36 mollusk, were tested in this study. As a result, V. parahaemolyticus was detected in 123 (36.7%) of 335 seafood. The tdh gene was not detected in all strains, while the trh gene was detected in 3 strains (2.4%). According to antimicrobial susceptibility test, 116 strains (94.3%) represent resistance to ampicillin, and 1 strain (0.8%) represents resistance to trimethoprim/sulfametoxazole. However, all strains were sensitive to 9 antimicrobial agents, including amikacin, chloramphenicol, tetracycline, and more. Therefore, the risk of V. parahaemolyticus isolated from seafood in Gwangju is considered low, but continuous monitoring of V. parahaemolyticus in seafood is required.

• Journal of Food Hygiene and Safety
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• v.39 no.3
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• pp.231-238
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• 2024

Vibrio parahaemolyticus is a major seafood-borne pathogen commonly detected in marine environments. In Korea, V. parahaemolyticus-induced foodborne illnesses account for 7.5% of bacterial pathogen-related food poisonings. Moreover, the amount of antimicrobial agents used in aquatic cultures is continuously increasing. In this study, we isolated V. parahaemolyticus from seafood samples and performed antimicrobial susceptibility tests using the microbroth dilution method. Furthermore, using whole-genome sequencing, we identified antimicrobial resistance genes, virulence genes, and sequence types (STs). We could isolate V. parahaemolyticus from 47 (59.5%) of the 79 seafood samples we purchased from retail markets in Seoul and Chungcheong provinces. Antimicrobial susceptibility tests revealed that 2 and all of the 47 isolates were ampicillin-resistant (4.3%) and susceptible to all tested antimicrobial agents (100%), respectively. The genotype analysis revealed that all isolates carried beta-lactam-, tetracycline-, and chloramphenicol-associated antimicrobial resistance genes. However, we could detect fosfomycin resistance only in one isolate. Concerning the virulence genes, we detected T3SS1 and T3SS2-associated genes in all and one isolate, respectively. However, we could not detect the tdh and trh genes. Of the 47 isolates, 17 belonged to 15 different STs, including ST 658 with 3 isolates. The rest 30 isolates were identified as 25 new STs. The results of this study support the need for operating a continuous monitoring system to prevent foodborne illnesses and the spread of antimicrobial resistance genes in V. parahaemolyticus.

• Journal of Microbiology and Biotechnology
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• v.30 no.6
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• pp.856-867
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• 2020

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℃, 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.116-123
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• 2016

This study investigated the prevalence of Vibrio parahaemolyticus in the oyster Crassostrea gigas, which is commonly consumed raw. The presence of virulence factors and the antimicrobial susceptibility of isolates were also investigated. The overall prevalence rate of V. parahaemolyticus in oysters was 37.5% (36/96) and the range of concentrations was 30-11,000 MPN/100 g. PCR-based assays indicated that 9.6% (11/115) of the isolates were positive for the thermostable direct hemolysin-related hemolysin gene (trh), while none of the isolates were positive for the thermostable direct hemolysin gene (tdh). The Multiple Antibiotics Resistance (MAR) index was measured for 16 common antimicrobial agents and 46.1% (53/115) of the isolates had a MAR index > 0.2. The MAR index ranged from 0.07 to 0.73. The highest MAR index was observed with strain s150608, isolated in June 2015, which exhibited resistance to 11 antimicrobial agents. Our results demonstrate that oysters are high-risk sources of V. parahaemolyticus, although no antimicrobial agent was being used to promote growth or to treat bacterial infections in the sampled oyster-growing areas.