Effect of D-tryptophan on hemolysin production in Vibrio parahaemolyticus

Production of the Kanagawa hemolysin by a strain of Vibrio parahaemolyticus isolated from a gastroenteritis patient was found to correlate with the presence in cell lysates of two unidentified compounds, designated X and Y. The two compounds were present in cell lysates of the organism grown in peptone at the optimal pH for hemolysin synthesis but were not present when cell lysates were grown in peptone at a constant pH of 8.0. They were also absent in cells grown in synthetic medium at pH 6.2 without the addition of D-tryptophan, a condition under which hemolysin is not produced. Both X and Y were present intracellularly only from the time that D-tryptophan was added to synthetic medium, a known method of inducing hemolysin synthesis.     

Effect of Heat (Arrhenius Effect) on Crude Hemolysin of Vibrio parahaemolyticus

Crude hemolysins prepared from various strains of Vibrio parahaemolyticus, which give positive Kanagawa phenomenon, were partly inactivated by heating at 60 C, but not inactivated significantly by heating at 80 to 90 C. The similar phenomenon has been reported as the Arrhenius effect in staphylococcal alpha toxin.     

Urease-positive Vibrio parahaemolyticus strain.

An unusual strain of Vibrio parahaemolyticus was isolated from the site of a perforated appendix. This was the first reported case in which the vibrios demonstrated a positive urease reaction. In other respects, the strain conformed to the general characteristics of V. parahaemolyticus. It was susceptible to chloramphenicol, sulfamethoxazole-trimethoprim, tetracycline, neomycin, triple sulpha, gentamicin, and polymyxin B and produced the "Kanagawa phenomenon". However, its role as a causative pathogen of the diarrhea of the patient was debatable.     

Isolation of mucoid Vibrio parahaemolyticus strains

Mucoid strains of Vibrio parahaemolyticus were isolated from the stools of two asymptomatic carriers and a patient with gastroenteritis. The strains demonstrated biochemical reactions and antibiotic susceptibility typical of nonmucoid strains of V. parahaemolyticus isolated locally. The slime substance was typed by coagglutination and was antigenically similar to the capsular antigen of the same strain. Three different serotypes (O10:K24, O5:K17, and O5:K15) were involved.     

Effect of pH on the production of the Kanagawa hemolysin by Vibrio parahaemolyticus.

Cord factor--a mixture of 6,6'-diesters of alpha, alpha-D-trehalose with natural mycolic acids--which is purified from mycobacteria and other microorganisms, is known to have adjuvant activity as well as to enhance nonspecific resistance to infections and tumor development. In this work, trehalose 6,6'-dimycolate (TDM) was found to induce proliferative responses in rat thymus and lymph node cells. With the thymus cells, TDM responses were greater after removal of the adherent cell subpopulation. Consistent with this observation was the finding that addition of phagocytic cells purified from peritoneal or lymph node cell suspensions to nonadherent thymocytes abrogated the response of thymocytes to TDM. With the lymph node cells, the presence or removal of adherent cells had no major consequence on the TDM-induced proliferative response, since similar increases in deoxyribonucleic acid synthesis were observed with unfractionated and nonadherent cells. The difference between the sensitivities of thymus cells and lymph node cells to regulation by adherent cells indicated the existence of more than one type of TDM responder cell in rats. TDM also displayed marked stimulatory activity on thymus and lymph node cells from germ-free rats, ruling out the possibility that TDM might have triggered a specific, secondary, in vitro immune response. Expansion of a selected cell population(s) triggered by TDM may be involved in the manifestation of adjuvant activity and possibly other immunological properties of cord factor.     

Panophthalmitis caused by Vibrio parahaemolyticus.

We report a case of Vibrio parahaemolyticus panophthalmitis which resulted from contamination of a wound with water from a pond in inland Georgia. The pond was on the property of an oil refinery which receives crude oil from southern Mississippi. Cultures of the pond water 5 years later did not yield V. parahaemolyticus, but did yield non-O1 V. cholerae and had 0.28% sodium chloride content. V. parahaemolyticus may have been introduced into the pond along with oil transported from the Gulf of Mexico, and growth of this halophilic species may have been supported by salt from spilled crude oil.     

Study of capsular polysaccharide from Vibrio parahaemolyticus

The leading cause of food poisoning in both Taiwan and Japan is Vibrio parahaemolyticus infection, whose mechanism of enteropathogenesis is still unclear. To evaluate whether surface components are responsible for the intestinal adhesion of V. parahaemolyticus, we have developed a novel method for isolating the capsular polysaccharide (CPS) from V. parahaemolyticus (serotype O4:K8). We found that culturing of V. parahaemolyticus in broth for 1 week or more changed the colony form of the bacteria on an agar plate from opaque to translucent. The translucent colonies of V. parahaemolyticus contained little CPS and exhibited a much lower level of adherence to epithelial cells (Int-407) than the opaque colonies of the bacteria. Incubation of V. parahaemolyticus in medium supplemented with bile increased the levels of CPS and adherence. Treatment of V. parahaemolyticus with anti-CPS but not anti-LPS serum decreased the level of bacterial adherence. In addition, purified CPS bound to epithelial cells in a dose-dependent manner. Intranasal administration of CPS to mice in the presence of adjuvants such as immunostimulatory sequence oligodeoxynucleotides or cholera toxin elicited CPS-specific mucosal and systemic immune responses. These results indicate that CPS plays an important role in the adherence of V. parahaemolyticus to its target cells and may be considered a potential target for the development of a vaccine against this pathogen.     

Quantification of Vibrio parahaemolyticus,Vibrio vulnificus and Vibrio cholerae in French Mediterranean coastal lagoons

Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio cholerae are human pathogens. Little is known about these Vibrio spp. in the coastal lagoons of France. The purpose of this study was to investigate their incidence in water, shellfish and sediment of three French Mediterranean coastal lagoons using the most probable number-polymerase chain reaction (MPN-PCR). In summer, the total number of V. parahaemolyticus in water, sediment, mussels and clams collected from the three lagoons varied from 1 to >1.1 × 10³ MPN/l, 0.09 to 1.1 × 10³ MPN/ml, 9 to 210 MPN/g and 1.5 to 2.1 MPN/g, respectively. In winter, all samples except mussels contained V. parahaemolyticus, but at very low concentrations. Pathogenic (tdh- or trh2-positive) V. parahaemolyticus were present in water, sediment and shellfish samples collected from these lagoons. The number of V. vulnificus in water, sediment and shellfish samples ranged from 1 to 1.1 × 10³ MPN/l, 0.07 to 110 MPN/ml and 0.04 to 15 MPN/g, respectively, during summer. V. vulnificus was not detected during winter. V. cholerae was rarely detected in water and sediment during summer. In summary, results of this study highlight the finding that the three human pathogenic Vibrio spp. are present in the lagoons and constitute a potential public health hazard.     

Comparison of Molecular Methods for Typing Vibrio parahaemolyticus

An outbreak of Vibrio parahaemolyticus gastroenteritis on Canada's west coast in 1997 emphasized the need to develop molecular methods for differentiation and typing of these organisms. Isolates were analyzed by enterobacterial repetitive intergenic consensus sequence (ERIC) PCR, detection of restriction fragment length polymorphisms (RFLP) in rRNA genes (ribotyping), pulsed-field gel electrophoresis (PFGE), and RFLP analysis of the genetic locus encoding the polar flagellum (Fla locus RFLP analysis). ERIC PCR and ribotyping were the most informative typing methods, especially when used together, while Fla locus RFLP analysis was the least discriminatory. PFGE exhibited good discrimination but suffered from a high incidence of DNA degradation. ERIC PCR and ribotyping will be useful for the evaluation of genetic and epidemiological relationships among V. parahaemolyticus strains.     

副溶血性弧菌食物中毒分离株毒力基因检测及耐药性的调查

目的了解近年引起食物中毒的26株副溶性弧菌分离株的携带主要毒力基因的分子流行病学特征和耐药性状况,为制定相应的防控措施提供参考。方法根据副溶血性弧菌耐热直接溶血素（TDH）和耐热相关溶血素（TRH）基因序列设计PCR引物,建立PCR反应体系,检测26株从2005年11月至2008年8月发生的8起散发性食物中毒事件中分离的副溶血性弧菌菌株的毒力基因TDH和TRH,K—B法测定其药物敏感性。结果26株副溶血性弧菌有23株携带有TDH基因,阳性率为88％,所有菌株均未带有TRH基因;26株菌对亚胺培南、阿米卡星、头孢吡肟、头孢噻肟、庆大霉素、环丙沙星、哌拉西林、头孢哌酮、头孢他啶、头孢西丁等13种药物未见有耐药菌株;但对磺胺异恶唑、替卡西林、氨苄西林等有较高的耐药率,分别达76．9％、69．2％、80．8％。而对复方新诺明、四环素、头孢呋辛酯、头孢噻吩、头孢唑啉等也有耐药菌株的存在。结论带有TDH基因是近年引起食物中毒的副溶性弧菌分离株的主要分子流行病学特征,所分离菌株对多种常用药物敏感性高。研究结果为评价引起食物中毒的副溶性弧菌的分子流行病学特征和制定可行的防控措施提供了科学依据。     

Existence of Two Distinct Hemolysins in Vibrio parahaemolyticus

Two distinct hemolysins were demonstrated in Vibrio parahaemolyticus. A thermostable direct hemolysin purified from V. parahemolyticus WP-1, a Kanagawa phenomenon (KP)-positive strain, is antigenically different from a thermolabile hemolysin produced by V. parahaemolyticus T-3454, a KP-negative strain. The thermostable direct hemolysin was found in KP-positive strains but not in KP-negative strains. On the other hand, the thermolabile hemolysins were found in both KP-positive and -negative strains, although some KP-positive strains did not produce this hemolysin.     

一起副溶血性弧菌食物中毒的现场流行病学调查分析

目的查明一起食物中毒事件的发生原因和可疑危险因素来源。方法通过流行病学曲线及回顾性队列研究查找可疑餐次,对可疑餐次食物开展病例对照研究,分析食用不同食物与食物中毒的关联性,并采集可疑食物和病例等标本进行实验室检测。结果共发现87例病例,症状主要为腹泻（96.5%）、腹痛（91.9%）、呕吐（44.8%）、发热（32.2%）。20日午餐（RR=21,95%CI=9.2~47）、晚餐（RR=4.9,95%CI=3.3~7.3）均是本次疑似食物中毒的暴露餐次。烧鸭（OR=26,95%CI=5.7~118）和白切鸡（OR=21;95%CI=2.5~180）是发病的危险因素。厨师在对白切鸡及烧鸭切块过程中发生交叉污染可能是此次食物中毒的感染环节。病例肛拭子检测为副溶血性弧菌阳性。结论食用被副溶血性弧菌污染的白切鸡和烧鸭是导致本次食物中毒的主要原因,建议加强对餐饮机构厨师的监督管理,提高其卫生安全意识,防止类似事件再次发生。     

Urea-hydrolyzing Vibrio parahaemolyticus associated with acute gastroenteritis.

A case of gastroenteritis caused by a urea-hydrolyzing strain of Vibrio parahaemolyticus is presented. Urea-hydrolyzing strains of Vibrio parahaemolyticus have rarely been reported and have not been described previously as a cause of gastroenteritis in the United States. With the exception of urea hydrolysis and the methyl red test, the isolate had all the characteristics of V. parahaemolyticus. The need to screen suspicious non-lactose-fermenting colonies from stool specimens with the oxidase test is emphasized.     

Nature of the Kanagawa phenomenon of Vibrio parahaemolyticus.

In a study of the Kanagawa phenomenon of Vibrio parahaemolyticus, both Kanagawa-positive and -negative strains were found to produce hemolytic factors that could not be differentiated on Wagatsuma blood agar. The presence of fermentable carbohydrates in media containing high concentrations of NaCl promoted the growth of V. parahaemolyticus and resulted in a marked decrease in medium pH and increased hemolysin production. The Kanagawa hemolysis of test strains differed according to the carbohydrates added. Clearly defined Kanagawa hemolysis was observed in blood agars of high salt content, but the distinction was lost in media containing 3% NaCl. From the results of this study, the Kanagawa hemolysis was interpreted as an expression of quantitative difference in hemolysin production, a conclusion that is clearly demonstrated on special blood agar of high salt content.     

Wound infection caused by Kanagawa-negative Vibrio parahaemolyticus.

Kanagawa-positive Vibrio parahaemolyticus strains are considered to be human pathogens and are most commonly associated with summer diarrhea. Kanagawa-negative strains are most frequently isolated from the environment and are generally considered to be nonpathogens. We report a wound infection caused by a Kanagawa-negative V. parahaemolyticus strain. The infection occurred in October, an unusual time of the year for a V. parahaemolyticus infection to occur in the mid-Atlantic region of the United States.