RESUMEN
The present study aimed to prepare usnic acid (UA)-loaded chitosan (CS) nanoparticles (UA-CS NPs) and evaluate its antibacterial activity against biofilm-forming pathogenic bacteria. UA-CS NPs were prepared through simple ionic gelification of UA with CS, and further characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and field-emission transmission electron microscopy. The UA-CS NPs presented a loading capacity (LC) of 5.2%, encapsulation efficiency (EE) of 24%, and a spherical shape and rough surface. The maximum release of UA was higher in pH 1.2 buffer solution as compared to that in pH 6.8 and 7.4 buffer solution. The average size and zeta potential of the UA-CS NPs was 311.5 ± 49.9 nm in diameter and +27.3 ± 0.8 mV, respectively. The newly prepared UA-CS NPs exhibited antibacterial activity against persister cells obtained from the stationary phase in batch culture, mature biofilms, and antibiotic-induced gram-positive and gram-negative pathogenic bacteria. Exposure of sub-inhibitory concentrations of UA-CS NPs to the bacterial cells resulted in a change in morphology. The present study suggests an alternative method for the application of UA into nanoparticles. Furthermore, the anti-persister activity of UA-CS NPs may be another possible strategy for the treatment of infections caused by biofilm-forming pathogenic bacteria.
Asunto(s)
Antibacterianos/farmacología , Benzofuranos/farmacología , Biopelículas , Quitosano/farmacología , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Animales , Antibacterianos/química , Benzofuranos/química , Quitosano/química , Humanos , NanopartículasRESUMEN
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 59â¯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.
Asunto(s)
Antibacterianos/farmacología , Metales Pesados/farmacología , Ostreidae/microbiología , Mariscos/microbiología , Vibrio parahaemolyticus/efectos de los fármacos , Animales , Acuicultura , Farmacorresistencia Bacteriana/efectos de los fármacos , Farmacorresistencia Bacteriana/genética , Microbiología de Alimentos , Humanos , Pruebas de Sensibilidad Microbiana , República de Corea , Vibrio parahaemolyticus/genética , Virulencia/genéticaRESUMEN
Levels of Escherichia coli and male-specific bacteriophages (MSBs) were determined in the filter feeders obtained from retail markets, commercial farms, and wild beds in Korea. The accumulation and elimination of E. coli and MSBs were compared between ascidians and bivalves (oysters and mussels) during relaying and depuration. E. coli concentrations in ascidians from retail markets ranged between < 20 and 460 most probable number/100 g while MSBs were not detected. E. coli levels in bivalves from commercial farms and wild beds were not significantly different but bacterial levels in ascidians were consistently lower. Ascidians exhibited much lower ability than bivalves to accumulate E. coli and MSBs during relaying in a polluted coastal area. This study also shows that an equilibrium was developed between levels of microbes in water and ascidians and shellfish during relaying. E. coli and MSBs in ascidians decreased quickly during depuration in a clean seawater tank. However, after 1 day, E. coli in bivalves decreased by only 1.1-1.6 logs, and the elimination of MSBs was negligible. Therefore, depuration is an effective means to reduce the health risk of contaminated ascidians.
Asunto(s)
Bacteriófagos/metabolismo , Bivalvos/microbiología , Bivalvos/virología , Escherichia coli/metabolismo , Urocordados/microbiología , Urocordados/virología , Animales , Masculino , Ostreidae/microbiología , República de Corea , Agua de Mar , Mariscos/microbiologíaRESUMEN
Vibrio parahaemolyticus, found frequently in oysters, is the most prevalent gastroenteritis-causing pathogen in Korea and in several other Asian countries. This study monitored changes in the environmental parameters and occurrence of V. parahaemolyticus in oyster aquaculture sites. Of the 44 presumed V. parahaemolyticus isolates obtained, when tested against 16 antibiotics, 90.9, 86.4, and 75.0% of the 44 isolates exhibited resistance to vancomycin, ampicillin, and streptomycin, respectively. PCR analysis for the presence of the toxR gene confirmed 31 of the 44 isolates as being positive V. parahaemolyticus strains. The toxR positive isolates were tested for the presence of thermostable direct hemolysin (tdh) and tdh-related hemolysin (trh) virulence genes. Only 9.1% toxR positive isolate exhibit the trh gene and none of the isolates were tested positive for tdh. The occurrence of multi drug resistance strains in the environment could be an indication of excessive usage of antibiotics in agriculture and aquaculture fields.
Asunto(s)
Farmacorresistencia Bacteriana , Ostreidae/microbiología , Vibrio parahaemolyticus/efectos de los fármacos , Vibrio parahaemolyticus/genética , Animales , Antibacterianos/farmacología , Acuicultura , Asia , Toxinas Bacterianas/genética , Genes Bacterianos , Proteínas Hemolisinas/genética , Reacción en Cadena de la Polimerasa , República de Corea , Mariscos , Vibrio parahaemolyticus/patogenicidad , Virulencia , Factores de Virulencia/genéticaRESUMEN
OBJECTIVE: We examined the prevalence rates of Internet gaming disorder among South Korean middle school students, the dominant symptoms of Internet gaming disorder, and the interrelationships between such disorder and non-psychotic psychological symptoms (ie, anxiety, depression, and impulsiveness) and with physical aggression. METHODS: Data were collected from a national sample of 2024 students (70.3% gamers; 50.6% boys). Gaming disorder and prevalent symptoms were measured by the 9 diagnostic criteria proposed in DSM-5. RESULTS: Our results showed 5.9% of the sample (boys 10.4%, girls 1.2%) was classified as adolescents with gaming disorder. Meanwhile, 8% (boys 14.2%, girls 5.9%) of the sample was found to be at high risk of gaming disorder. The prevalent symptoms were mood modification, behavioral salience, conflict, withdrawal, and relapse, in that order. A total of 9.2%, 15.1%, and 10.9% of the adolescents with gaming disorder had non-psychotic psychological anxiety, depression, and impulsiveness symptoms, respectively. Nearly 11% of students with Internet gaming disorder had 2 non-psychotic psychological symptoms or more. CONCLUSION: These results provide supportive empirical evidence that Internet gaming disorder can lead to severe distress and that it can be associated with comorbid symptoms that are relevant to development or continuance of the gaming disorder.
Asunto(s)
Agresión , Conducta Adictiva/psicología , Adolescente , Agresión/psicología , Ansiedad/epidemiología , Ansiedad/psicología , Conducta Adictiva/epidemiología , Depresión/epidemiología , Depresión/psicología , Femenino , Humanos , Masculino , Prevalencia , República de Corea/epidemiologíaRESUMEN
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.
Asunto(s)
Antibacterianos/farmacología , Crassostrea/química , Vibrio parahaemolyticus/aislamiento & purificación , Animales , Acuicultura , Farmacorresistencia Bacteriana , Pruebas de Sensibilidad Microbiana , República de Corea , Mariscos , Vibrio parahaemolyticus/efectos de los fármacos , Vibrio parahaemolyticus/genética , Virulencia/genéticaRESUMEN
Okadaic acid (OA), dinophysistoxin-1 (DTX1), pectenotoxin-2, and yessotoxin (YTX) are classes of lipophilic toxins found in marine animals. OA and DTX1 accumulation causes diarrhetic shellfish poisoning, a worldwide public health problem. Diarrhetic shellfish poisoning has not previously been reported in gastropods, which are widely consumed in Korea. Seasonal variation in marine lipophilic toxins in gastropods was investigated using liquid chromatography-tandem mass spectrometry. Eighty specimens of Neptunea cumingii, 65 specimens of Rapana venosa, and 95 specimens of Batillus cornutus were collected at the Tongyeong fish market on the southern coast of Korea between May 2009 and December 2010. OA, DTX1, and YTX were detected in meat and digestive glands in all gastropod species studied. Pectenotoxin-2 was not found in any sample tested. Lipophilic toxins were detected in the digestive glands of gastropods; no lipophilic toxin was detected in the salivary glands of the carnivorous gastropods, N. cumingii and R. venosa. The highest concentrations of OA (21.5 ng/g) and DTX1 (8.4 ng/g) were detected in the digestive glands of R. venosa, and the maximum concentration of YTX (13.7 ng/g) was found in the digestive glands of N. cumingii. The maximum toxicities in gastropod tissues were lower than the European standard for acceptable levels. The concentrations of lipophilic toxins in carnivorous gastropods showed a high degree of seasonal variation; lipophilic toxins in carnivorous gastropods were found predominantly in spring and summer. This is the first report of the occurrence of lipophilic toxins in Korean gastropods.
Asunto(s)
Contaminación de Alimentos/análisis , Gastrópodos/química , Ácido Ocadaico/aislamiento & purificación , Oxocinas/aislamiento & purificación , Piranos/aislamiento & purificación , Mariscos/análisis , Animales , Seguridad de Productos para el Consumidor , Inocuidad de los Alimentos , Humanos , Venenos de Moluscos , República de Corea , Estaciones del Año , Mariscos/normas , Especificidad de la EspecieRESUMEN
To better understand critical aspects of diarrhetic shellfish poisoning (DSP) occurrence in a chief producing region of bivalves in Korea, the geographical and annual variation of DSP toxins and other lipophilic toxins in mussels (Mytilus galloprovincialis) and oysters (Crassostrea gigas) were investigated by liquid chromatography-tandem mass spectrometry in an area on the south coast of Korea from 2007 to 2009. The total lipophilic shellfish toxin (LST) levels in bivalves showed geographical and annual variations. LSTs were detected mostly in the hepatopancreas of mussels from Jinhae Bay throughout the entire year, except in November and December of 2007, but were almost undetectable in all samples during the entire year in 2009. The peak DSP toxin (okadaic acid plus dinophysistoxin 1) levels in the hepatopancreas of mussels from Jinhae Bay and the Tongyeong region were 945.3 and 37.6 ng/g, respectively. The DSP toxin content was about 10 times higher in mussels than in oysters collected from the same region. The major toxins in bivalves were okadaic acid and dinophysistoxin 1; however, pectenotoxin 2 or yessotoxin was occasionally detected as a major component. The results of a quantitative analysis of phytoplankton showed that Dinophysis acuminata was the most probable source of the LSTs, with the exception of yessotoxin. When the highest DSP toxin level was measured (945.3 ng/g in the hepatopancreas of mussels from Jinhae Bay), the toxin concentration in whole mussel tissue was calculated to be 114.0 ng/g. The calculated highest DSP toxin level in whole oyster tissue from both regions was 15.0 ng/g. The calculated maximum toxicities in whole mussel and oyster tissues were lower than the regulatory limit (160 to 200 ng/g) in Korea, the European Union, and the United States. Korean oysters (242 samples) and mussels (214 samples) were thus deemed safe for consumption. But because such variation was detected in a relatively small area of the coast, it is possible that at some locations or during a specific period LST levels could exceed the standard and a few consumers could be at risk of experiencing DSP.
Asunto(s)
Bivalvos/química , Inocuidad de los Alimentos , Ostreidae/química , Intoxicación por Mariscos/epidemiología , Animales , Seguridad de Productos para el Consumidor , Diarrea/epidemiología , Diarrea/etiología , Diarrea/prevención & control , Humanos , Corea (Geográfico)/epidemiología , Estaciones del Año , Mariscos/análisis , Intoxicación por Mariscos/etiología , Intoxicación por Mariscos/prevención & control , Especificidad de la Especie , Espectrometría de Masas en TándemRESUMEN
The antimicrobial resistance patterns to 15 antimicrobial agents of Vibrio parahaemolyticus and Vibrio alginolyticus isolated from farmed fishes, including olive flounder (Paralichthys olivaceus), black rockfish (Sebastes schlegeli), red sea bream (Pagrus major), and sea bass (Lateolabrax japonicus), were investigated from 2005 through 2007. A total of 218 V. parahaemolyticus isolates and 153 V. alginolyticus isolates were obtained from the 180 fish samples collected from fish farms located along the southern coast of Korea. We found that 65.1% of V. parahaemolyticus and 85.6% of V. alginolyticus isolates showed antimicrobial resistance against more than one antimicrobial agent. The prevalence of resistance in V. parahaemolyticus isolates to ampicillin was highest (57.8%), followed by resistance to rifampin (11.9%), streptomycin (8.7%), and trimethoprim (6.4%). V. alginolyticus isolates were also most resistant to ampicillin (75.2%), followed by tetracycline (15.0%), trimethoprim (12.4%), and rifampin (9.8%). The prevalence of multiresistance to four or more antimicrobials was higher in V. alginolyticus (11.1%) than in V. parahaemolyticus (5%). Antimicrobial resistance rates per isolate of V. parahaemolyticus and V. alginolyticus possessing virulence genes were not different from those of the rest of the isolates.
Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana , Contaminación de Alimentos/análisis , Alimentos Marinos/microbiología , Vibrio alginolyticus/efectos de los fármacos , Vibrio parahaemolyticus/efectos de los fármacos , Animales , Seguridad de Productos para el Consumidor , Farmacorresistencia Bacteriana Múltiple , Peces , Humanos , Corea (Geográfico) , Pruebas de Sensibilidad Microbiana , Prevalencia , Vibrio alginolyticus/aislamiento & purificación , Vibrio parahaemolyticus/aislamiento & purificaciónRESUMEN
Noroviruses (NoV) are the key cause of acute epidemic gastroenteritis, and oysters harvested from NoV-polluted sea areas are considered as the significant vectors of viral transmission. To improve NoV detection from oyster using nested reverse transcription-polymerase chain reaction (RT-PCR), we evaluated the sensitivity and specificity of previously published primer pairs and the efficiency of different RNA extraction procedures. Among the primer pairs used for RT-PCR, the sensitivity of GIF1/GIR1-GIF2/GIR1 and GIIF1/GIIR1-GIIF2/GIIR1 was higher than that of other primer pairs used in nested RT-PCR for the detection of NoV genogroup I (NoV GI) and NoV GII from both NoV-positive stool suspension and NoV-seeded oyster concentrates, respectively; the resulting products showed neither unspecific bands in the positive samples nor false-positive bands in the negative controls. The extraction of NoV RNA from oyster samples using a QIAamp® Viral RNA Mini kit with a QIAshredder™ Homogenizer pretreatment afforded more efficient recovery (mean recovery for NoV GI and GII, 6.4%) and the procedure was less time consuming (<30 min) than most other RNA extraction procedures. The results of RNA extraction procedure and primer pairs evaluated by nested RT-PCR assay in this study can be useful for monitoring NoV contamination in oysters, which is an indicator of possible public health risks.
Asunto(s)
Cartilla de ADN , Norovirus/aislamiento & purificación , Ostreidae/virología , ARN/aislamiento & purificación , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Virología/métodos , Animales , Cartilla de ADN/genética , Heces/virología , Humanos , Reacción en Cadena de la Polimerasa/métodos , Sensibilidad y Especificidad , Manejo de Especímenes/métodosRESUMEN
In this study, we constructed a rapid detection system for a foodborne pathogen, Vibrio parahaemolyticus, by using enzyme-linked immunosorbent assay (ELISA)-on-a-chip (EOC) biosensor technology to minimize the risk of infection by the microorganism. The EOC results showed a detection capability of approximately 6.2x10(5) cells per ml, which was significantly higher than that of the conventional rapid test kit. However, this high level of sensitivity required cultivation of the pathogen prior to analysis, which typically exceeded a day. To shorten the test period, we combined the EOC technology with immunomagnetic separation (IMS), which could enhance the sensitivity of the biosensor. IMS was carried out with magnetic particles coated with a monoclonal antibody specific to the microbe. To test the performance of the IMS-EOC method, fish intestine samples were prepared by artificially inoculating less than 1 or 5 CFU/10 g, allowing for enrichment over predetermined times, and analyzing the sample by using the EOC sensor after concentrating the culture 86-fold via IMS. Using this approach, the bacterium was detected after (at most) 9 h, which approximately corresponds to standard working hours. Thus, the IMS-EOC method allowed for the rapid detection of V. parahaemolyticus, which is responsible for foodborne diseases, and this method could be used for early isolation of contaminated foods before distribution.