Enhanced subtyping scheme for Salmonella enteritidis

To improve pulsed-field gel electrophoresis-based strain discrimination of 76 Salmonella Enteritidis strains, we evaluated 6 macro-restriction endonucleases, separately and in various combinations. One 3-enzyme subset, SfiI/PacI/NotI, was highly discriminatory. Five different indices, including the Simpson diversity index, supported this 3-enzyme combination for improved differentiation of S. Enteritidis.     

Extended phage-typing scheme for Campylobacter jejuni and Campylobacter coli.

The extended phage-typing scheme described for Campylobacter jejuni and Campylobacter coli has established 46 different phage types using 19 typing phages. Altogether 754 campylobacter isolates, 672 C. jejuni and 82 C. coli, isolated from human and non-human sources received from 17 different countries were phage-typed. Overall, 80.6% of the total isolates were typable. Among typable strains, 9 phage types (3, 5, 10, 11, 18, 19, 23, 26 and 44) represented 57.0% of the strains, 21.3% of the strains belonged to another 37 phage types and the remaining 2.3% of isolates were designated atypical. The most common phage type 11 (140/754) was frequently observed among C. jejuni isolates from human (113/561) and non-human sources (18/111), whereas type 44 was frequent among C. coli isolates from human (22/59) and from non-human sources (8/23). A study of the animal host-associations of common phage types showed that contaminated cattle and poultry appear to be the most common sources of human infection. The greatest variety of phage types was observed in Canada (24 phage types), followed by Portugal (17 types) and the UK (14 types), reflecting the larger sample sizes from these countries. Phage type 11 was encountered in 12 different countries and prevalence of other phage types varied from one country to another. The number of isolates typable with the scheme varied from 93.2% (261/280) in Canada to 61% (47/77) in Thailand. However, the number and diversity of phage types makes phage typing the method of choice in epidemiological studies of campylobacter infections.     

一起肠炎沙门菌所致食物中毒的调查报告

2007-05—20／23，德昌县麻栗乡民主村发生1起因大办丧宴，食物受肠炎沙门菌污染引起的食物中毒。现将调查结果报告如下。     

Developing epidemiological markers for Shigella sonnei: a proposed phage-typing scheme

BACKGROUND: Shigella sonnei isolates are homogeneous when examined by serological methods. Since this micro-organism is one of the common isolates in outbreaks of shigellosis, a strong necessity was felt to find a sub-division of it, useful in epidemiological studies. METHODS: 103 phages previously found to be active on various groups of Enterobacteriaceae were tested on 129 strains of S. sonnei. Among 47 phages active on S. sonnei, eight were selected as giving the best differentiation between the isolates and clear-cut reactions. RESULTS: Twelve main phage-types were identified. Among the strains of phage-type 1, some showed full sensitivity to all the eight phages; others showed minor differences in the sensitivity to one or some of them. The significance of these minor phage-types has to be further analyzed. CONCLUSIONS: A tentative phage-typing scheme appropriate for S. sonnei has been proposed. This method provides a potentially useful tool for epidemiological study of this organism. Further validation of the scheme using local isolates is necessary.     

Extended phage-typing scheme for Escherichia coli O157:H7

In Canada, the number of human isolates of verotoxigenic (VT + ve) Escherichia coli O157:H7 from diarrhoeal cases and haemolytic uraemic syndrome and haemorrhagic colitis has increased from 25 in 1982 to 2384 in 1989. A total of 3273 VT + ve E. coli O157:H7 strains (3255 strains isolated in Canada and 18 isolates from other countries) were phage typed. The phage typing scheme has been extended from 14 to 62 phage types. Of these, five types occurred exclusively in other countries (type 47 in Japan; and types 49, 50, 51 and 52 in the U.K.). Thirty-five different phage types were identified in Canada; only nine of these (1, 2, 4, 8, 14, 21, 23, 31 and 32), each accounted for more than 1% of the cases from human sources. The same nine types were the only ones observed among the isolates from non-human sources (meat and slaughter houses) suggesting a food-borne transmission in most of the human cases. Phage types 1 (30.5%); 4 (21%); 8 (13.5%); 31 (8.9%) and 14 (8%) were encountered in varying frequencies in most of the provinces; infrequently occurring phage types also showed regional variation. Thirteen different phage types were identified among 151 outbreaks representing 556 isolates of E. coli O157:H7. More than one phage type were encountered in 12 outbreaks whereas in 141 outbreaks, all strains in each, had the same phage type.     

一起由两种血清型沙门氏菌共同引起的食源性疾病暴发调查

目的 调查一起高考期间学校食源性疾病暴发的原因,为预防类似事件的发生提供参考,并为食源性疾病事件调查溯源提供可借鉴的经验。方法 采用描述性流行病学方法分析流行特征,采集标本进行实验室相关检测,综合分析判定疫情原因。结果 该起事件首发病例发病时间为6月6日,持续4 d,罹患率为10.77%(155/1 436);临床表现以腹泻、腹痛、发热为主;病例均有在学校2层食堂的就餐史,调查到一楼食堂就餐的5例病例均食用了6日中餐鸡蛋香干和(或)卤牛肉,在三楼食堂就餐的86例病例食用了6日中餐卤牛肉和(或)7日晚餐卤鸡腿的占95.35%。同时发现食堂食品加工用具和盛装容器存在生熟混用的情况。从一楼食堂就餐的5份病例生物标本、3份食堂从业人员肛拭子、留样食物(鸡蛋香干)中检出肠炎沙门氏菌,且PFGE图谱一致;从三楼食堂就餐的8份病例生物标本、留样食物(卤牛肉、卤鸡腿)中检出鼠伤寒沙门氏菌,且PFGE图谱一致。结论 该事件为一起因食品加工用具和容器生熟不分所致的食源性疾病暴发,致病因子为肠炎和鼠伤寒两种不同血清型沙门氏菌。建议规范和落实学校餐饮卫生监管,确保加工用具和容器生熟分开,加强从业人员食品安全培训,制定定期体检制度,防止类似事件再次发生。     

一起沙门氏菌引起的自助餐食物中毒案例分析

目的 对一起食物中毒事件进行流行病学调查分析和病原菌检验以确定引起本次食物中毒的原因,为今后预防食物中毒事件的发生提供数据参考。方法 采用现场流行病学调查和实验室检验相结合的方法。结果 共同就餐者216人,发病者26人,发病率为9.96%,根据患者临床表现、潜伏期、现场卫生状况、流行病学特点及实验室检验结果,确定此次食物中毒病原体为沙门氏菌,中毒原因是食用了被沙门氏菌污染的食物。结论 引起本次食物中毒的原因是多方面的,今后应加强食品卫生管理和宣传教育,提高对食源性疾病的监控能力,广泛宣传食物中毒的危害和预防知识,避免类似事件再次发生。     

A study of the epidemiology of Salmonella bareilly in India using a new phage-typing system

A total of 637 strains of Salmonella bareilly received from different parts of India between 1959 and 1985 were phage typed using five locally isolated wild phages. The overall typability was 94.5% and 11 different phage types could be defined. Phage types 10 and 1 were the most prevalent and the geographical and source distribution is described.     

Salmonella enteritidis phage types in Germany

In order to monitor the epidemiological situation ofS. enteritidis in Germany, in 1990–91 1138 isolates from more than 180 locations in West Germany were phage typed. 1124 strains (98.8%) from all sources were typeable, belonging to 21 different phage types (PT). PT4 strains were isolated most frequently (70.8%). In addition, PT7, 25, 34 and 8 were of epidemiological relevance with incidences of 7.2 to 4.5%. The comparison of data shows that in Germany, like in other parts of Europe, PT4 predominates. This phage type is, however, infrequent in North America, where PT8 has the highest incidence.     

Salmonella enteritidis outbreak in a home for the aged

BACKGROUND: An outbreak of gastroenteritis caused by Salmonella Enteritidis (SE), phagotype 1, reported at a senior citizen living facility in Burgos on November 15, 1999 is discussed. The objective of the research of this outbreak was that of ascertaining the source of infection, the mechanism by which it was transmitted and to propose the suitable measures for preventing any recurrence of this problem. METHODS: An observational retrospective cohort study has been made by surveying 106 of a total of 119 residents and 9 employees at the center in question. The Relative Risk of being affected by this disorder has been estimated in terms of the intake of different foods. Logic Regression was employed for calculating the odds ratio adjusted by age, sex and by the intake of foods and wine. The concordance of the clinical diagnosis with the coproculture diagnosis was studied using the Cohen's Kappa index of agreement. RESULTS: A total of 42 individuals reported symptoms (37 residents and 5 employees). The clinical attack rate was 36.5%. Forty-five (45) of the 91 coprocultures performed (82 on residents and 9 on employees) were positive (41 in residents and 4 in employees). The attack rate for cases confirmed by coproculture was 49.5% among those investigated. Fried breaded milk and flour batter sweets was the food product implicated epidemiologically with the onset of the outbreak: RR 3.25 (C.I at 95% 1.10-9.59). The protective effect of the wine (Odds Ratio: 0.68) was not high enough to be statistically significant (p = 0.36). The Kappa index was 0.43 (p < 0.001), which reveals very little agreement between the clinical diagnosis and the coproculture diagnosis. CONCLUSIONS: Epidemiological evidence exists of the intake of fired breaded milk and flour batter sweets having been the mechanism for the transmission of the infection, and the food product in question having been stored at room temperature having been the determining contributing factor in the start of the outbreak. This reveals that the best way of preventing this type of outbreaks are clean habits and practices on the part of all those involved in the food-handling sector.     

Competitive exclusion of Salmonella enteritidis by Salmonella gallinarum in poultry

Salmonella Enteritidis emerged as a major egg-associated pathogen in the late 20th century. Epidemiologic data from England, Wales, and the United States indicate that S. Enteritidis filled the ecologic niche vacated by eradication of S. Gallinarum from poultry, leading to an epidemic increase in human infections. We tested this hypothesis by retrospective analysis of epidemiologic surveys in Germany and demonstrated that the number of human S. Enteritidis cases is inversely related to the prevalence of S. Gallinarum in poultry. Mathematical models combining epidemiology with population biology suggest that S. Gallinarum competitively excluded S. Enteritidis from poultry flocks early in the 20th century.     

Bavaroise and an epidemic of Salmonella enteritidis

In the literature an association is made between the increasing prevalence of Salmonella enteritidis in poultry products and in the isolates of patients with gastroenteritis, without sufficient evidence of a causal relationship between the increasing prevalences. A microbiological and epidemiological analysis of a food poisoning incident among 239 visitors of a restaurant by way of food specific attack rates and food specific infection rates revealed an epidemic of 70 cases of S. enteritidis enteritis. The analysis supports the causal relationship with the consumption of an infected, unhygienically prepared egg product, in this case bavaroise.     

Egg-related Salmonella enteritidis, Italy, 1991

In recent years, Salmonella enteritidis has become an increasingly important public health problem in Italy. In some parts of the country, the fraction of total human salmonella isolates accounted for by S. enteritidis has risen from 3-4% in the mid-1980s to more than 30% in 1990. Between 1990 and 1991, the number of reported S. enteritidis outbreaks increased more than sixfold. The 33 outbreaks reported in 1991 occurred in seven contiguous regions in northern and central Italy and were clustered in time between June and October; in the majority, products containing raw or undercooked shell eggs were implicated. Five of the egg-related outbreaks that occurred within a 30 kilometre radius over a 7-week period were investigated in detail. A phage type 1 strain containing a 38·9 MDa plasmid appeared responsible for three of the outbreaks, while in the remaining two a phage type 4 strain, also with a 38·9 MDa plasmid was isolated. Efforts are being made to enhance epidemiological surveillance and laboratory evaluation, and the use of pasteurized eggs has been recommended for high-risk populations.     

Interrelationships between strains of Salmonella enteritidis.

In contrast to S. typhimurium [19], S. enteritidis is a serotype which has its primary food-animal reservoir in poultry. To date, phage typing has been of paramount importance in studying the epidemiology of this serotype and in particular, has demonstrated the involvement of both poultry meat and whole shell eggs in the transmission of S. enteritidis PT4 to humans. The findings discussed above describe various aspects of the serotype, particularly in relation to the involvement of both LPS and plasmids in its virulence and phage type identity (Fig. 2). These findings have led to an increased understanding of the biology of this serotype, which is of major importance in human food-poisoning in England and Wales at the present time.     

A nosocomial outbreak of Salmonella enteritidis associated with lyophilized enteral nutrition

Outbreaks of Salmonella spp. gastro-enteritis in hospitals are of concern because of the increased susceptibility of patients and associated high morbidity. This study is a report of a nosocomial outbreak of Salmonella enteritidis associated with enteral nutrition. In December 1999, one sample of enteral feed tested positive for S. enteritidis. During the subsequent 6 weeks, eight cases of nosocomial salmonellosis occurred. Patients involved in the outbreak were aged 19-79 years (median = 36.5), and salmonella was isolated from the blood of two patients. All patients were receiving enteral nutrition at the time and all had diarrhoea. Three patients died. All 13 employees of the Nutrition Department were asymptomatic and their stool samples were negative. Environmental and water samples were also negative. The diet, however, contained lyophilized egg albumin. Molecular typing showed that the isolates of seven patients were indistinguishable from the one obtained from the enteral diet. It was thought that the nosocomial salmonellosis probably occurred due to the use of a commercial lyophilized diet. Another method of processing diets may be necessary to ensure patient safety.     

不同来源肠炎沙门菌的溯源研究

目的:应用脉冲场凝胶电泳(PFGE)技术对不同来源的肠炎沙门菌进行分子分型,为政府部门修订相关的卫生法规提供了重要科学依据。方法:采用限制性内切酶Xba I,对广州地区2009-2011年间从业人员健康体检和食物中毒中检出的36株肠炎沙门菌进行PFGE分子分型,用BioNumerics Version 4.0软件(复选Dice相关系数和UPGMA方法)进行聚类分析。结果:36株肠炎沙门菌PFGE图谱显示菌株之间密切相关,相似度在88.8%～100%。结论:从业人员健康体检和食物中毒分离的肠炎沙门菌菌株之间存在较高分子水平的同源性,提示健康带菌从业人员是沙门菌食物中毒不可忽视的污染源。