Seasonal distribution of total and pathogenic Vibrio parahaemolyticus in Chesapeake Bay oysters and waters

The objectives of this study were to investigate the seasonal distribution of total and pathogenic Vibrio parahaemolyticus in the Chesapeake Bay oysters and waters, and to determine the degree of association between V. parahaemolyticus densities and selected environmental parameters. Oyster and water samples were collected monthly from three sites in Chesapeake Bay, Maryland from November 2004 through October 2005. During collection of samples, water temperature, salinity, turbidity, dissolved oxygen, pH, chlorophyll a, and fecal coliform levels in oysters were also determined. V. parahaemolyticus levels were enumerated by a quantitative direct-plating method followed by DNA colony hybridization; presence/absence was further determined by overnight broth enrichment followed by either standard colony isolation or real-time PCR. The thermolabile hemolysin (tlh) gene and thermostable direct hemolysin (tdh) gene were targeted for detection of total and pathogenic V. parahaemolyticus, respectively, for both direct plating and enrichment. The thermostable related hemolysin (trh) gene, which is a presumptive pathogenicity marker, was targeted only for the enrichment approach. By direct plating, colonies producing tlh signals were detected in 79% of oyster samples at densities ranging from 1.5x10(1) to 6.0x10(2) CFU/g. Pathogenic V. parahaemolyticus (tdh+) was detected in 3% (level was 10 CFU/g) of oyster samples while no V. parahaemolyticus was detected in water samples. By the enrichment approach with standard colony isolation, 67% of oyster and 55% of water samples (n=33) were positive for total V. parahaemolyticus, and all samples were negative for pathogenic V. parahaemolyticus. In contrast, enrichment followed by real-time PCR detected tlh, tdh and trh in 100%, 20% and 40% of oyster and 100%, 13% and 40% of water enrichments collected from June to October 2005, respectively. V. parahaemolyticus densities in oysters varied seasonally and were found to be positively correlated with water temperature, turbidity, and dissolved oxygen.     

Vibrio vulnificus and Vibrio parahaemolyticus in U.S. retail shell oysters: a national survey from June 1998 to July 1999.

From June 1998 to July 1999, 370 lots of oysters in the shell were sampled at 275 different establishments (71%, restaurants or oyster bars; 27%, retail seafood markets: and 2%, wholesale seafood markets) in coastal and inland markets throughout the United States. The oysters were harvested from the Gulf (49%). Pacific (14%), Mid-Atlantic (18%), and North Atlantic (11%) Coasts of the United States and from Canada (8%). Densities of Vibrio vulnificus and Vibrio parahaemolyticus were determined using a modification of the most probable number (MPN) techniques described in the Food and Drug Administration's Bacteriological Analytical Manual. DNA probes and enzyme immunoassay were used to identify suspect isolates and to determine the presence of the thermostable direct hemolysin gene associated with pathogenicity of V. parahaemolyticus. Densities of both V. vulnifcus and V. parahaemolyticus in market oysters from all harvest regions followed a seasonal distribution, with highest densities in the summer. Highest densities of both organisms were observed in oysters harvested from the Gulf Coast, where densities often exceeded 10,000 MPN/g. The majority (78%) of lots harvested in the North Atlantic, Pacific, and Canadian Coasts had V. vulnificus densities below the detectable level of 0.2 MPN/g; none exceeded 100 MPN/g. V. parahaemolyticus densities were greater than those of V. vulnificus in lots from these same areas, with some lots exceeding 1,000 MPN/g for V. parahaemolyticus. Some lots from the Mid-Atlantic states exceeded 10,000 MPN/g for both V. vulnificus and V. parahaemolyicus. Overall, there was a significant correlation between V. vulificus and V. parahaemolyticus densities (r = 0.72, n = 202, P < 0.0001), but neither density correlated with salinity. Storage time significantly affected the V. vulnificus (10% decrease per day) and V. parahaemolyticus (7% decrease per day) densities in market oysters. The thermostable direct hemolysin gene associated with V parahaemolyticus virulence was detected in 9 of 3,429 (0.3%) V. parahaemolyticus cultures and in 8 of 198 (4.0%) lots of oysters. These data can be used to estimate the exposure of raw oyster consumers to V. vulnificus and V. parahaemolyticus.     

Growth and survival of Vibrio parahaemolyticus in postharvest American oysters

Oysters at the retail stage of distribution generally contain greater densities of Vibrio parahaemolyticus than do oysters at harvest. The objective of this study was to determine the effects of postharvest storage at 26 and 3 degrees C on the growth and survival of naturally occurring V. parahaemolyticus in shellstock American oysters (Crassostrea virginica). Oysters were collected monthly from May 1998 through April 1999 from Mobile Bay, Alabama, and their V. parahaemolyticus densities were determined after 0, 5, 10, and 24 h of postharvest storage at 26 degrees C. After 24 h of storage at 26 degrees C, oysters were transferred to a refrigerator at 3 degrees C and analyzed 14 to 17 days later. V. parahaemolyticus numbers were determined by a direct plating method involving an alkaline-phosphatase-labeled DNA probe that targets the species-specific thermolabile hemolysin gene (tlh-AP) to identify suspect isolates. From April to December, when water temperatures at harvest were >20 degrees C, the geometric mean harvest density of V. parahaemolyticus was 130 CFU/g. When water temperatures were <20 degrees C, the geometric mean harvest density was 15 CFU/g. After harvest, V. parahaemolyticus multiplied rapidly in live oysters held at 26 degrees C, showing a 50-fold increase (1.7 log CFU/g) at 10 h and a 790-fold increase (2.9 log CFU/g) at 24 h (April through December). Average V. parahaemolyticus numbers showed a sixfold decrease (0.8 log CFU/g) after approximately 14 days of refrigeration. These results indicate that V. parahaemolyticus can grow rapidly in unrefrigerated oysters.     

Oyster-to-oyster variability in levels of Vibrio parahaemolyticus

This study examined the variability in the levels of total and pathogenic Vibrio parahaemolyticus in individual oysters. Twenty oysters were collected on three occasions (in June, July, and September 2001) from a site near Mobile Bay, Ala. Ten of these oysters were tested immediately, and 10 were tested after 24 h of storage at 26 degrees C. Levels of total and pathogenic V. parahaemolyticus were determined by alkaline phosphatase-labeled DNA probe procedures targeting the thermolabile hemolysin and thermostable direct hemolysin genes, respectively. Similar V. parahaemolyticus levels (200 to 2,000 CFU/g) were found in nearly 90% of the oysters (for all sampling occasions) prior to storage. The log-transformed densities (means +/- standard deviations) of V. parahaemolyticus in oysters immediately after harvest were 2.90 +/- 0.91, 2.88 +/- 0.36, and 2.47 +/- 0.26 log10 CFU/g for June, July, and September, respectively. After storage for 24 h at 26 degrees C, the mean V. parahaemolyticus densities increased approximately 13- to 26-fold. Before storage, pathogenic V. parahaemolyticus was detected in 40% (10 to 20 CFU/g) of the oysters collected in June and July but was not detected in any oysters collected in September. After storage, pathogenic V. parahaemolyticus was detected in some oysters at levels of > 100 CFU/g. These data should aid in the development of sampling protocols for oyster monitoring programs and in the determination of exposure distributions associated with raw oyster consumption.     

基于环介导等温扩增法(LAMP)检测上海市售贝类产品中副溶血性弧菌的毒力菌株

基于环介导等温扩增法(LAMP)对上海市8-10月市售贝类产品中副溶血性弧菌毒力菌株(tdh和trh毒力基因)进行检测分析,共检测贝类样品180份,6个常规品种,实验同时采用PCR测定方法进行对比。结果表明,含tdh和trh毒力基因的副溶血性弧菌在市售贝类中的检出率分别是12.77%和11.66%,PCR的分析结果为11.11%和7.78%。对分离的毒力菌株进行血清型分型后发现了2株O3:K6型副溶血性弧菌,其中1株为毒力基因双阳性菌(tdh+/trh+)。2株O3:K6型副溶血性弧菌的PFGE条带型相似度较高(相似度90%)。这些结果表明上海市售贝类产品中副溶血性弧菌毒力菌株存在一定的污染,应引起足够重视。双阳性O3:K6型副溶血性弧菌的出现值得关注,应对各血清型菌株尤其是O3:K6型副溶血性弧菌的流行情况加强监测。PCR检测结果对比分析表明,LAMP方法适用于贝类产品中副溶血性弧菌毒力菌株的检测分析。     

Evaluation of nonisotopic DNA hybridization methods for detection of the tdh gene of vibrio parahaemolyticus

Production of the thermostable direct hemolysin (TDH) by Vibrio parahaemolyticus is associated with pathogenicity of the organism and is encoded by the tdh gene. The timely resolution of seafood-associated outbreaks requires rapid and accurate detection of pathogenic V. parahaemolyticus. The specificity of alkaline phosphatase- and digoxigenin-labeled tdh gene probes was evaluated against 61 strains of V. parahaemolyticus (including isolates from recent outbreaks involving oysters from the Pacific Northwest, Texas, and New York), 85 strains of other vibrios, and 7 strains of non-vibrio species from clinical and environmental sources. The probes were specific for detection of the V. parahaemolyticus tdh gene.     

Occurrence of Vibrio spp. in fish and shellfish collected from the Swiss market

The genus Vibrio includes gram-negative bacteria that inhabit estuarine ecosystems. V. cholerae, V. parahaemolyticus, and V. vulnificus pose a considerable public health threat as agents of sporadic and epidemic foodborne infections associated with the consumption of raw or undercooked contaminated fish or shellfish. In this study, we analyzed 138 fish and shellfish samples collected from the Swiss market (fish fillets [n = 102], bivalves [n = 34], and squid [n = 2]). Microbiological analysis was done according to International Organization for Standardization method 21872-1/21872-2:2007, using thiosulfate citrate bile sucrose agar and chromID Vibrio agar as selective agar. Presumptive-positive colonies on thiosulfate citrate bile sucrose agar or chromID Vibrio agar were picked and were identified by the API 20E and species-specific PCR systems. V. cholerae isolates were tested further by PCR for the presence of the cholera toxin A subunit gene (ctxA). V. parahaemolyticus isolates were tested by PCR for genes encoding for thermostable direct hemolysin (tdh) and TDH-related hemolysin (trh). V. cholerae was isolated from three samples and V. parahaemolyticus from eight samples. None of these strains harbored species-specific virulence factors. Further, V. alginolyticus was isolated from 40 samples, and V. fluvialis was isolated from 1 sample. Our study provides, for the first time, data for the assessment of exposure to Vibrio spp. in raw fish and bivalves consumed in Switzerland.     

Occurrence of Vibrio and other pathogenic bacteria in Mytilus galloprovincialis (mussels) harvested from Adriatic Sea, Italy.

Sixty-two samples of Mytilus galloprovincialis (mussels) harvested from approved shellfish waters in the Adriatic Sea were examined for the presence of Vibrio, Salmonella, Campylobacter, and verocytotoxin producing Escherichia coli. Vibrio spp. were isolated from 48.4% of samples; the species most frequently found were V. alginolyticus (32.2%) and V. vulnificus (17.7%), followed by V. cincinnatiensis (3.2%), V. parahaemolyticus (1.6%), V. fluvialis (1.6%) and V. cholerae non-O1 (1.6%). V. parahaemolyticus resulted negative to Kanagawa-phenomenon and to PCR amplification of tdh gene. V. cholerae resulted negative to PCR amplification of sto gene. No Salmonella, Campylobacter, or E. coli verocytotoxin-producing strains were isolated. The results of this study suggest the potential risk of ingesting raw or undercooked mussels due to the frequent presence of potentially pathogenic Vibrio species.     

Increased sensitivity in PCR detection of tdh-positive Vibrio parahaemolyticus in seafood with purified template DNA

PCR is an important method for the detection of thermostable direct hemolysin gene (tdh)-positive (pathogenic hemolysin-producing) strains of Vibrio parahaemolyticus in seafood because tdh-negative (nonpathogenic) V. parahaemolyticus strains often contaminate seafood and interfere with the direct isolation of tdh-positive V. parahaemolyticus. In this study, the use of PCR to detect the tdh gene of V. parahaemolyticus in various seafoods artificially contaminated with tdh-positive V. parahaemolyticus was examined. PCR was inhibited by substances in oysters, squid, mackerel, and yellowtail but not by cod, sea bream, scallop, short-necked clam, and shrimp. To improve detection, DNA was purified by either the silica membrane method, the glass fiber method, or the magnetic separation method, and the purified DNA was used as the PCR primer template. For all samples, the use of the silica membrane method and the glass fiber method increased detection sensitivity. The results of this study demonstrate that the use of properly purified template DNA for PCR markedly increases the effectiveness of the method in detecting pathogenic tdh-positive V. parahaemolyticus in contaminated seafood.     

食品中副溶血性弧菌toxR和tdh基因双色荧光PCR检测方法的建立

目的 建立对副溶血性弧菌（Vibrio parahaemolyticus）特异性检测toxR（跨膜转录激活蛋白）基因和tdh（热稳定性直接溶血素）毒力基因的Taqman探针双色荧光PCR检测方法。方法 根据副溶血性弧菌toxR基因和tdh基因,分别设计引物和探针,建立Taqman探针双色荧光PCR扩增体系,进行特异性、灵敏度试验;对副溶血性弧菌分离菌株实施检测,了解其tdh基因和tdh基因分布情况。结果 结果表明,副溶血性弧菌标准菌株和3株从食物中毒患者中分离获得的分离株均出现toxR基因和tdh扩增曲线,而溶藻弧菌、单增李斯特菌等31株弧菌属其他菌株和肠杆菌科的菌株未见扩增曲线。从食品中分离的37株副溶血性弧菌分离株均未携带tdh毒力基因。副溶血性弧菌检测灵敏度可达到3.6×102 cfu/mL。结论 该方法可用于同时检测食品中副溶血性弧菌的特异性和毒力基因。     

Effect of intertidal exposure on Vibrio parahaemolyticus levels in Pacific Northwest oysters

Interest in Vibrio parahaemolyticus (Vp) increased in the United States following Vp-associated gastroenteritis outbreaks in 1997 and 1998 involving the West Coast and other areas. The present study evaluated multiple aspects of Vp ecology in the Pacific Northwest with three objectives: (i) to determine the effect of low-tide exposure on Vp levels in oysters, (ii) to determine the relationship between total and pathogenic Vp, and (iii) to examine sediments and aquatic fauna as reservoirs for pathogenic Vp. Samples were collected from intertidal reefs along Hood Canal, Wash., in August 2001. Fecal matter from marine mammals and aquatic birds as well as intestinal contents from bottom-dwelling fish were tested. Total and pathogenic Vp levels in all the samples were enumerated with colony hybridization procedures using DNA probes that targeted the thermolabile direct hemolysin (tlh) and thermostable direct hemolysin (tdh) genes, respectively. The mean Vp densities in oysters were four to eight times greater at maximum exposure than at the corresponding first exposure. While tdh-positive Vp counts were generally < or = 10 CFU/g at first exposure, counts as high as 160 CFU/g were found at maximum exposure. Vp concentrations in sediments were not significantly different from those in oysters at maximum exposure. Pathogenic (tdh positive) Vp was detected in 9 of 42 (21%) oyster samples at maximum exposure, in 5 of 19 (26%) sediment samples, but in 0 of 9 excreta samples. These results demonstrate that summer conditions permit the multiplication of Vp in oysters exposed by a receding tide.     

Risk of Vibrio transmission linked to the consumption of crustaceans in coastal towns of Côte d'Ivoire

The purpose of this study was to assess the risk of Vibrio spp. transmission from crustaceans to humans in two coastal towns of C?te d'Ivoire. Bacteriologic analysis was performed on 322 crustacean samples obtained from six markets in Abidjan and one in Dabou. Suspected Vibrio colonies were identified by morphological, cultural, biochemical, and molecular tests and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. PCR assays were used to further characterize Vibrio strains. A survey on consumption of crustaceans was conducted among 120 randomly selected households in Abidjan. Overall, Vibrio spp. were isolated from 7.8% of the crustacean samples studied, at levels as high as 6.3 log CFU/g. Of the Vibrio strains identified, 40% were V. alginolyticus, 36% were V. parahaemolyticus, and 24% were nontoxigenic V. cholerae; the latter two species can cause mild to severe forms of seafood-associated gastroenteritis. Among interviewed households, 11.7% reported daily consumption of crustaceans, confirming the high probability of exposure of human population to Vibrio spp., and 7.5% reported symptoms of food poisoning after consumption of crustaceans. The absence of genes encoding major virulence factors in the studied strains, i.e., cholera toxin (ctxA and ctxB) in V. cholerae and thermostable direct hemolysin (tdh) and thermostable direct hemolysin-related hemolysin (trh) in V. parahaemolyticus, does not exclude the possibility of exposure to pathogenic strains. However, human infections are not common because most households (96.7%) boil crustaceans, usually for at least 45 min (85.9% of households) before consumption.     

Populations of Vibrio parahaemolyticus in retail oysters from Florida using two methods

Vibrio parahaemolyticus is a naturally occurring estuarine bacterium that is often associated with gastroenteritis in humans following consumption of raw molluscan shellfish. A number of studies have investigated the environmental distribution of V. parahaemolyticus, but little is known about the levels of this organism during distribution of oysters or at the point of consumption. Duplicate samples of shellstock oysters were collected monthly (September 1997 to May 1998) from the same four restaurants and three wholesale seafood markets in the Gainesville, Fla. area and analyzed for total V. parahaemolyticus densities using two methods: a standard MPN method (BAM-MPN) and a new direct plating procedure (direct-VPAP). Both methods employed an alkaline phosphatase-labeled DNA probe (VPAP) targeting the species-specific thermolabile hemolysin (tlh) gene to confirm suspect colonies as V. parahaemolyticus. The highest monthly geometric mean V. parahaemolyticus density was observed in October of 1997 (approximately 3,000/g) with similarly high values during September and November of 1997. From December 1997 to May 1998 mean densities were generally less than 100/g, falling to approximately 10/g in February and March. A strong correlation (r = 0.78) between the direct-VPAP and BAM-MPN methods for determining V. parahaemolyticus densities in market-level oysters was observed. The direct-VPAP method was more rapid and precise while the BAM-MPN was more sensitive and may better recover stressed cells. The utilization of the VPAP probe for identification of V. parahaemolyticus sharply reduced the labor for either method compared to biochemical identification techniques used in earlier V. parahaemolyticus surveys.     

Levels of Vibrio parahaemolyticus and thermostable direct hemolysin gene-positive organisms in retail seafood determined by the most probable number-polymerase chain reaction (MPN-PCR) method

The incidence and levels of Vibrio parahaemolyticus and thermostable direct hemolysin gene (tdh)-positive organisms in retail seafood were determined. The most probable number-polymerase chain reaction (MPN-PCR) method using a PCR procedure targeting the species-specific thermolabile hemolysin gene (tlh) and tdh was used to determine the levels of V. parahaemolyticus and tdh-positive organisms, respectively. In seafood for raw consumption, V. parahaemolyticus was found in four (13.3%) of 30 fish samples, 11 (55.0%) of 20 crustacean samples, and 29 (96.7%) of 30 mollusc samples. Levels of V. parahaemolyticus were below 10(4) MPN/100 g in all fish and crustacean samples tested. However, they were above 10(4) MPN/100 g in 11 (36.7%) of the 30 mollusc samples. In all seafood for raw consumption, the level of tdh-positive organisms was below the limit of detection (< 30 MPN/100 g). In seafood for cooking, V. parahaemolyticus was found in 15 (75.0%) of 20 fish samples, nine (45.0%) of 20 crustacean sample, and 20 (100%) of 20 mollusc samples. Levels of V. parahaemolyticus were above 10(4) MPN/100 g in only three (15.0%) and one (5.0%) of the 20 fish and 20 crustacean samples, respectively. However, they were above 10(4) MPN/100 g in 18 (90.0%) of the 20 mollusc samples. In seven (35.0%) of the 20 mollusc samples, tdh-positive organisms were found and their levels ranged from 3.6x10 to 1.1 x 103 MPN/100 g. From four of seven tdhpositive samples, tdh-positive V. parahaemolyticus was isolated.     

Occurrence of the tdh and trh genes in Vibrio parahaemolyticus isolates from waters and raw shellfish collected in two French coastal areas and from seafood imported into France

The occurrence of the hemolysin genes, tdh and trh, in Vibrio parahaemolyticus strains isolated from environmental samples collected in two French coastal areas, clinical samples, and seafood products imported into France was studied. Polymerase chain reaction (PCR) with two sets of primers was used to detect the hemolysin genes. Most of the clinical isolates (91%) and 1.5% of the isolates from seafood possessed the hemolysin genes. Three and fifteen percent, respectively, of the two groups of environmental strains carried the hemolysin genes depending on the geographic site. The tdh and trh genes play important roles in virulence. Thus, our results indicate that pathogenic V. parahaemolyticus isolates are present in French coastal areas and in seafood imported into France. Furthermore, they may also be present in French seafood products.     

Occurrence of Vibrio parahaemolyticus in Two Oregon Oyster-growing Bays

ABSTRACT: Occurrence of Vibrio parahaemolyticus in 2 Oregon oyster-growing areas (Yaquina andTillamook Bays) was studied from November 2002 to October 2003. Vibrio parahaemolyticus was detected in 15.0% of oyster, 20.0% of seawater, and 47.5% of sediment samples with very low levels of pathogenic strains being detected in oysters (≤3.6 most probable number [MPN] /g). The densities of total and pathogenic V. parahaemolyticus were higher in sediment (≤1100 and ≤43 MPN/g) than in seawater (≤15 and ≤3.6 MPN/100 mL) or oyster (≤43 and ≤3.6 MPN/ g). Densities of V. parahaemolyticus in both bays were positively correlated to water temperatures ( P < 0.01), with higher densities in samples being detected in summer, especially July and August. There was no correlation between the densities of V. parahaemolyticus and water salinity or the densities of V. parahaemolyticus and bacterial populations in seawater. Freshly harvested oysters should be kept at refrigeration temperatures to prevent rapid growth of pathogenic V. parahaemolyticus in contaminated oysters.     

The occurrence of Vibrio species in tropical shrimp culture environments; implications for food safety

The occurrence of various Vibrio species in water, sediment and shrimp samples from multiple shrimp farm environments from the east and west coast of India was studied. The relative abundance was higher in west coast farms (ca. 10(4) cfu/ml water) when compared to the east coast (ca. 10(2) cfu/ml water). Vibrio alginolyticus (3-19%), V. parahaemolyticus (2-13%), V. harveyi (1-7%) and V. vulnificus (1-4%) were the predominant Vibrio species identified by standard biochemical testing. In some cases, V. cholerae could be found, but all isolates were negative for the cholera toxin (ctx) gene that is associated with choleragenic strains. The biochemical identification of V. parahaemolyticus, the other human pathogen among the species mentioned above, was confirmed by PCR targeting the toxR gene and a 387 bp chromosomal locus specific for this species. Furthermore, the presence of the virulence-associated tdh (thermostable direct haemolysin) and trh (TDH-related haemolysin) genes in the V. parahaemolyticus isolates was also detected by PCR. Only 2 out of 47 isolates were tdh positive and one contained the trh gene. However, since V. cholerae, V. parahaemolyticus and V. vulnificus species are recognized as a major cause of seafood-borne illness, it is important to pay attention to post-harvest handling and adequate cooking.     

烟台地区食源性疾病中副溶血性弧菌的病原特征及溯源分析

目的了解烟台地区引发食物中毒的副溶血性弧菌分离菌株的主要血清型、抗生素耐药情况、致病力的强弱以及传播流行趋势。方法对2017～2019年11起食物中毒爆发事件中分离的14株副溶血性弧菌进行血清分型;采用微量肉汤稀释法进行药敏试验;采用PCR技术检测毒力基因不耐热溶血素(tld)、耐药直接溶血素(tdh)和溶血相关溶血素(trh);采用脉冲场电泳(pulse-field gel electrophoresis,PFGE)进行分子分型的溯源分析。结果引发烟台地区食物中毒爆发的副溶血性弧菌血清型多样,但以O3:K6型为主(28.6%),分离菌株中11株(78.6%)表现为tdh阳性和trh阴性,3株(21.4%)未携带tdh和trh基因,对头孢唑啉(71.4%)、多粘菌素E(57.1%)、美罗培南和阿莫西林/克拉维酸(7.1%)均出现耐药情况,对氨苄西林(21.4%)、多粘菌素B(14.3%)为中度敏感,耐药谱显示没有出现对3种以上同时耐药的情况,但是42.9%的分离菌株对2种同时耐药情况。结论烟台地区引发食物中毒爆发的副溶血性弧菌以O3:K6型为主,主要携带tdh,对头孢唑啉耐药和多粘菌素耐药普遍存在,具有聚集性爆发的风险,因此加强腹泻病的监测,充分利用国家致病菌识别网集中进行本地区分离菌株的病原特征研究是防控食物中毒爆发的有效手段。     

Western 斑点印迹法技术检测致病性副溶血弧菌

目的：对副溶血弧菌(Vibrio parahaemolyticus,VP)的直接耐热溶血毒素(thermostable direct hemolysin,TDH)进行分离纯化,建立Western 斑点印迹法技术检测致病性副溶血弧菌的方法。方法：用直接耐热溶血毒素免疫小鼠得到特异性抗血清,利用棋盘方法确定免疫血清最佳工作浓度,并对致病性与非致病性副溶血弧菌分别进行特异性测定。结果：最佳免疫血清最佳工作浓度为1:3200;检测致病性副溶血弧菌为阳性,非致病性副溶血弧菌属呈阴性。结论：Western 斑点印迹法技术可以特异性检测致病性副溶血弧菌,灵敏度高、操作简单,可用肉眼判定结果。     

食物来源和食源性疾病来源的副溶血性弧菌的生物学特性比较研究

目的了解温州市平阳县食物来源和食源性疾病来源的副溶血性弧菌的血清群分布特点以及耐热直接溶血素(TDH)和TDH相关溶血素(TRH)检出情况。方法以59株副溶血性弧菌食品风险监测分离株和39株副溶血性弧菌食源性疾病监测分离株为研究对象,用标准血清进行血清学分群,应用实时荧光定量聚合酶链式反应(PCR)法检测tdh基因和trh基因。结果食品风险监测分离株检出9个血清群,无优势菌群;食源性疾病监测分离株检出O1、O3和O4;以O3和O4为主,分别占48.7%(19/39)和46.2%(18/39)。食源性疾病监测分离株的毒力基因检测结果为38株仅含有tdh基因,1株仅含有trh基因,而食品风险监测分离株仅检出1株只含有tdh基因的菌株。结论平阳县食品风险监测中分离的副溶血性弧菌菌株与分离自食源性疾病监测的副溶血性弧菌菌株的主要血清型、毒力基因都存在差别。本研究为预防和快速检验副溶血性弧菌引起的食源性疾病提供了科学依据。