Genomic fingerprinting of shigatoxin-producing Escherichia coli (STEC) strains: comparison of pulsed-field gel electrophoresis (PFGE) and fluorescent amplified-fragment-length polymorphism (FAFLP)

For epidemiological studies of shigatoxin-producing Escherichia coli (STEC) infections, rapid, reproducible and highly discriminative methods are required. In this study, we examined the performance of the fluorescent amplified-fragment-length polymorphism (FAFLP) technique for epidemiological fingerprinting of STEC isolates and compared it to the acknowledged fingerprinting method pulsed-field gel electrophoresis (PFGE). A total of 88 STEC isolates, including 82 of serotype O157:H7 or O157:H-, were subjected to fingerprinting by both PFGE and FAFLP. The isolates included sporadic and epidemiologically related strains of both animal and human origin from widespread geographical locations. The FAFLP fingerprint patterns confirmed the clonal nature of STEC O157 strains. Among the 82 O157:H7/H- isolates belonging to 49 distinct groups of epidemiological unrelated isolates, 24 FAFLP profiles and 51 PFGE patterns were obtained. Thus, PFGE had a higher discriminatory power than FAFLP and overall correlated better to available epidemiological data. Consequently, the PFGE technique remains the method of choice in epidemiological investigations of STEC infections.     

Use of AFLP and PFGE to discriminate between Salmonella enterica serovar Typhimurium DT126 isolates from separate food-related outbreaks in Australia

In 2001 Salmonella enterica serovar Typhimurium definitive phage-type (DT) 126 was isolated at higher frequency in Australia compared to other S. Typhimurium phage types and in comparison to previous years. Associated with this increase was the implication of this phage type in a number of food-related outbreaks. We compared fluorescent amplified fragment length polymorphism (FAFLP) to pulsed-field gel electrophoresis (PFGE), the current 'gold standard' for molecular typing of Salmonella for the discrimination between outbreak-associated isolates and epidemiologically unrelated DT126 strains. FAFLP showed a greater ability to discriminate between isolates than PFGE, with 16 groups of clusters or individual isolates with < 90% similarity to each other compared to three groups as determined by PFGE. Both methods were able to discriminate between isolates from two separate outbreaks in South Australia and isolates associated with an outbreak at a restaurant in New South Wales. The resolving power of both methods was not sufficient to separate all epidemiologically unrelated DT126 isolates from the outbreak isolates. We conclude that amplified fragment length polymorphism is a useful tool to assist in the discrimination of S. Typhimurium DT126 isolates.     

2011-2012年杭州市肠道沙门菌临床分离株的分子型别分析

目的研究2011-2012年杭州市肠道沙门菌临床分离株的型别,了解本地菌株分子流行病学特征。方法对66株肠道沙门菌临床分离株进行血清分型和多位点序列分型(MLST)。对其中主要血清型:鼠伤寒、甲型副伤寒、萨雷甲尼和肠炎沙门菌菌株进行脉冲场凝胶电泳(PFGE)分型。结果分布于21个血清型的66株沙门菌分成26个ST型别。发现一株纽波特沙门菌为新型ST1690。菌株血清型与MLST型别数据库中所对应的血清型符合率为100.00%。9株甲型副伤寒沙门菌的PFGE带型完全一致(P7型),与先前杭州流行菌株有差异(P1-P6型)。6株肠炎沙门菌分成4个PFGE型,型间最小相似性为92.70%。13株鼠伤寒沙门菌分为11个PFGE型,型间最小相似性为71.70%。7株萨雷甲尼沙门菌分成4个PFGE型别,型间最小相似性为91.00%。结论近年杭州腹泻病人中流行的肠道沙门菌菌株主要血清型为鼠伤寒、甲型副伤寒、萨雷甲尼和肠炎等。甲型副伤寒沙门菌菌株在杭州出现了新PFGE型别。MLST数据可以对沙门菌血清学鉴定提供一定的帮助。     

Epidemiological analysis of Salmonella enterica Enteritidis isolates in Japan by phage-typing and pulsed-field gel electrophoresis.

Salmonella enterica serotype Enteritidis isolates of phage types (PTs) PT1, PT4, PT13a and PT22 derived from sporadic cases and outbreaks of food poisoning in Japan during 1994 and 1995 were analysed by pulsed-field gel electrophoresis (PFGE). While PT1 strains from 5 different outbreaks showed 14 PFGE patterns, 5 PFGE patterns were observed among PT4 isolates from 5 different outbreaks and 6 independent isolates from imported chicken. Interestingly, 8 out of 9 PT4 strains associated with foreign travel to Southeast Asia were indistinguishable in PFGE pattern from 5 independent isolates of imported chicken from England. Although both PT13a and PT22 were first reported in Japan in 1994, PT22 showed various PFGE patterns compared to PT13a which had the same pattern within an outbreak, unlike PT1. These results could indicate that multiple clonal lines of PT1 and PT22 had already spread while relatively fewer clonal lines of PT4 and PT13a might exist in Japan.     

Pulsed-field gel electrophoresis subtyping database for foodborne Salmonella enterica serotype discrimination

Nontyphoid Salmonella is one of the main causes of bacterial gastroenteritis worldwide and is responsible for 65% of reported outbreaks of foodborne diseases in France. Serotyping is widely used for isolate preliminary identification, but it poorly discriminates strains. Rapid, efficient molecular subtyping tools have therefore been developed for the investigation of outbreaks. We evaluated the performance of the pulsed-field gel electrophoresis (PFGE) method for discrimination of 31 Salmonella serotypes frequently isolated in France. We set up a genomic database of Salmonella strains isolated from food, animals, the environment, and humans to improve the management of contamination and reactions to foodborne disease outbreaks. We studied 1128 isolates by PFGE, according to the standardized PulseNet protocol. We identified 452 PFGE patterns, 67.5% of which corresponded to a single isolate. The ability of this method to distinguish between isolates was estimated by calculating the Simpson index and the 95% confidence interval. Values obtained ranged between 0.33 (0.11-0.54) to 0.99 (0.96-1.00), depending on serotype. Epidemiological information about isolates was used for analyses of intra- and interserotype diversity results and for determining whether PFGE patterns were linked to the source of the isolate. Clustering analysis of the PFGE patterns obtained confirmed that serotype and PFGE genotype were closely linked. Some PFGE patterns were identified as major patterns, each of these patterns being found in at least 10 isolates. The database generated has already proved its effectiveness in epidemiological investigations in livestock production and foodborne outbreaks.     

Molecular epidemiological investigation of a diffuse outbreak caused by Salmonella enterica serotype Montevideo isolates in Osaka Prefecture, Japan

In Osaka Prefecture, Japan, three foodborne outbreaks were caused by Salmonella enterica serotype Montevideo in rapid succession between September 2007 and May 2008. Further, Salmonella Montevideo was also isolated from several sporadic diarrhea patients and asymptomatic carriers examined during approximately the identical period. To investigate the relatedness of the isolates, we performed antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE) analysis, and multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA) for 29 Salmonella Montevideo isolates obtained in this region between 1991 and 2008. Although antimicrobial susceptibility tests had low discriminatory power, PFGE patterns revealed 17 unique types with <90% similarity in combined analyses involving XbaI and BlnI. Moreover, we detected three VNTR loci that were useful to genotype Salmonella Montevideo isolates, with our method ultimately classifying the isolates into 11 MLVA types based on differences in repeat unit number in each examined locus. Six isolates obtained from patients of two separate foodborne disease outbreaks, one sporadic patient, and three different carriers between 2007 and 2008 had nearly identical PFGE patterns and were classified into the identical MLVA type; further, the isolates with this PFGE and MLVA pattern appeared only at that time between 1991 and 2008. These data strongly suggest that genetically identical Salmonella Montevideo strains may have caused the 2007 and 2008 outbreaks in Osaka Prefecture. Our results demonstrate that PFGE using XbaI and BlnI is useful for discriminating between Salmonella Montevideo isolates, even within a limited area, and reconfirm that continuous epidemiological surveillance for bacterial intestinal infections such as salmonellosis may be useful to not only monitor changes in the genetic diversity of isolates, but to also detect diffuse outbreaks.     

Distribution of molecular subtypes within Salmonella enterica serotype Enteritidis phage type 4 and S. Typhimurium definitive phage type 104 in nine European countries, 2000-2004: results of an international multi-centre study

This study investigates the distribution of pulsed-field gel electrophoresis (PFGE) profiles within Salmonella enterica serotype Enteritidis phage type (PT) 4 and S. Typhimurium definitive phage type (DT) 104, from cases of human infection in nine European countries from 2000 to 2004. Isolates were subtyped using standardized methods and gel images submitted by each participating country to the coordinating centre (Health Protection Agency Centre for Infections, London, UK), where they were entered into a central database, developed within BioNumerics software, and designated using an agreed nomenclature. S. Enteritidis PT4 (n=3637) was differentiated into 38 different profiles. Simpson's index of diversity (D) of profiles ranged from 0.2 to 0.4. Profile SENTXB.0001 represented at least 80% of all profiles in each country. S. Typhimurium DT104 (n=1202) was differentiated into 28 different profile types. Simpson's D was at least 0.6 in all countries except in Austria and Italy. In both these countries over 74% of S. Typhimurium DT104 profiles were STYMXB.0013. Profile STYMXB.0061, was predominant in Denmark, Spain, Finland and England and Wales where it represented between 36% and 45% of profiles. Profile STYMXB.0001 represented nearly half of all profiles in Scotland and 23% in England and Wales. PFGE is proving useful for further discrimination within S. Enteritidis PT4 and S. Typhimurium DT104. Ascertainment of international outbreaks involving common serotypes and phage types may be increased by the timely pooling of PFGE profiles within a central database readily accessible to all participating countries.     

Pheno-genotyping of Salmonella enterica serotype Enteritidis isolates identified in Sicily during a reemergence period

After an upward trend paralleling that occurring in most European countries, including Italy, since October 2002 Salmonella enterica serotype Enteritidis (S. Enteritidis) has again gained the first position among outbreak and sporadic human isolates of Salmonella in Sicily. Because phage typing of S. Enteritidis has many technical and epidemiological limitations and molecular methods have proved to be poorly discriminative for this organism, multiple typing, using phage typing together with pulsed field gel electrophoresis (PFGE) and plasmid profiling on a sample of fifty human and poultry isolates identified during the period October 2002 to May 2003 in Sicily, was chosen as the most valuable strategy to explore key features of this new epidemic wave. Although the limited number of strains imposes a cautious interpretation of the results, an apparently increasing phage type heterogeneity has emerged with rise in PT6 as the more striking event. While PFGE has confirmed the findings by other authors about the close genetic homogeneity between PT4 and PT6, plasmid profiling has provided discriminative patterns for PT6 strains. Combined phenotypic and genotypic profiles are necessary for epidemiological studies and public health investigations on S. enteritidis.     

Laboratory-based surveillance of non-typhoidal Salmonella infections in Guangdong Province, China

Salmonella is one of the most common foodborne pathogens in humans. Laboratory-based surveillance for non-typhoidal Salmonella infection was conducted in Guangdong Province, China to improve understanding about the disease burden and detection of dispersed outbreaks. Salmonella isolated from patients with diarrhea were sent from 16 sentinel hospitals to local public health laboratories for confirmation, serotyping, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (PFGE). PFGE patterns were analyzed to identify clusters representing potential outbreaks. Between September 2009 and October 2010, 352 (4%) Salmonella isolates were obtained from 9167 stool specimens. Salmonella enterica serotype Typhimurium (45%) and Salmonella enterica serotype Enteritidis (13%) were the most common serotypes, and multidrug resistance was high, especially in Salmonella Typhimurium isolates. PFGE patterns of obtained Salmonella isolates were found to be diverse, but a unique PFGE pattern comprising 53 Salmonella Typhimurium isolates were found to occur almost exclusively in infants. Epidemiologic studies are ongoing to determine whether a common exposure is the source of the Salmonella Typhimurium strain frequently isolated from infants.     

Molecular characterization of Salmonella enterica serotype Enteritidis isolates from humans by antimicrobial resistance, virulence genes, and pulsed-field gel electrophoresis

Salmonella enterica serovar Enteritidis (S. Enteritidis) is a major serovar associated with human salmonellosis. A total of 425 clinical S. Enteritidis isolates of human origin were collected between June 2009 and September 2010 from North Carolina. The isolates were further characterized for antimicrobial susceptibility, antimicrobial resistance coding determinants, virulence genes, and fingerprint profiles to determine whether they were similar or different to the S. Enteritidis strain responsible for the human outbreak due to consumption of contaminated eggs. Ten different antimicrobial resistance phenotypes were observed with the highest frequency of resistance exhibited to ampicillin (n=10; 2.35%). The isolates were predominantly pansusceptible (n=409; 96.23%); however, seven isolates were multidrug resistant (MDR; i.e., resistant to three or more antimicrobials). Extended spectrum β-lactamase (ESBL) coding genes (bla(TEM) and bla(PSE)) were detected in the ampicillin-resistant isolates, whereas a single MDR isolate tested positive for class 1 integron (1 kb). The majority of the isolates (n=422; 99.3%) carried the invA, mgtC, stn, sopB, sopE1, and sefA virulence genes. However, 37 (8.7%) and 46 (10.82%) S. Enteritidis isolates tested negative for the plasmid encoded genes spvC and rck, respectively. Pulsed-field gel electrophoresis (PFGE) typing of 118 S. Enteritidis isolates by restriction enzymes XbaI and BlnI resulted in seven clusters, each with a discriminatory index (DI) of 0.715 and 0.785, respectively. The combination of XbaI-BlnI patterns generated a dendrogram with 14 clusters and a higher DI of 0.914. The PFGE profile of 80 isolates matched 100% with the S. Enteritidis strain that has been cited for the recent outbreak in the United States due to consumption of contaminated eggs. In conclusion, we identified a genotypic similar S. Enteritidis population in our study based on antimicrobial susceptibility, virulence gene, and PFGE fingerprint profiles.     

表型和分子分型技术在霍乱弧菌研究中的应用

目的分析1999～2005年广州地区O1群和O139群霍乱弧菌代表菌株的致病基因型和PFGE型别,确定霍乱菌株的分子流行病学特征和同源性,研究本地霍乱弧菌的分子特性。方法采用多重PCR方法检测霍乱弧菌的4种致病相关基因,采用限制性内切酶Not I,以脉冲场凝胶电泳技术(PFGE)对菌株进行分子分型,采用分型处理软件BioNumerics Version对PFGE图谱做聚类分析。结果本地霍乱弧菌代表株中存在3种致病基因型(A、B、C型),病例分离的霍乱弧菌多为A型基因,而环境分离的霍乱弧菌则多为C型和B型。总共96株霍乱弧菌分为60个不同的PFGE型,带型范围:8 kb-650 kb。相同或相近的PFGE型(相差1～3条带)存在于多次霍乱暴发疫情分离株中、环境分离霍乱与临床株之间、输入病例与本地病例分离霍乱弧菌间,不同的PFGE克隆型(4～6带及以上)的流行病学联系也较远。结论将致病基因分型、PFGE型与流行病学资料结合,揭示了本地霍乱菌株从受污染的珠江水及水产品传递给人并引起霍乱暴发、散发的特征,提示开展霍乱菌株PFGE分子分型监测及加强地区间合作的必要性和急迫性。     

2008-2009年北京市沙门菌流行特征和分子分型

目的 分析2008-2009年北京市沙门菌流行特征及脉冲场凝胶电泳(PFGE)分子分型. 方法 对2008-2009年通过WHO全球沙门菌监测系统及北京市肠道门诊监测系统分离到的137株沙门菌进行生化鉴定、血清分型和相关流行病学分析;利用PFGE进行分子分型. 结果 北京市2008-2009年沙门菌的流行具有明显季节性,6-9月份高发,共分离菌株84株,占64.1%(84/131);患者年龄多为18～40岁,占46.1%(58/128);男性80例,女性51例,男女比例为1.57:1.137株沙门菌分属于20种血清型,其中肠炎沙门菌和鼠伤寒沙门菌为优势菌型,分别占46.7%(64/137)和17.5%(24/137).共分71种PFGE带型,其中肠炎沙门菌和鼠伤寒沙门菌都有16种PFGE型别.肠炎沙门菌的4种PFGE型别(JEGX01.CN0001、JEGX01.CN0003、JFGX01.CN0002、JEGX01.CN0019)和鼠伤寒沙门菌的JPXX01.CN0001为优势分子型别. 结论 2008-2009年北京市沙门菌的流行具有性别、年龄和季节性分布特征;PFGE分子型别较多,且存在差异明显的多个克隆系.

Abstract：

Objective To study the epidemiological characteristics and molecular phenotypes of Salmonella by pulsed-field gel electrophoresis (PFGE) in Beijing from 2008 to 2009. Methods A total of one hundred thirty-seven isolates recovered from the WHO Global Samonella Surveillance system and entero clinic surveillance system were identified by biochemical tests and serotyping.The related epidemiological informations were also analyzed.The isolates were further typed by PFGE. Results The prevalence of Salmonella from 2008 to 2009 showed obvious seasonal character.High incidence occurred from June to September,and 64.1% (84/131) isolates were recovered in this period.Patients of 18-40 year-old were 46.1% (58/128) and 80 patients were male and 40 patients were female with the ratio of 1.57:1.These 137 Salmonella isolates belonged to 20 serotypes,including Enteritidis (46.7%,64/137) and Typhimurium (17.5%,24/137) as the dominant serotype.In total,71 PFGE profiles were identified.Four PFGE patterns of S.Enteritidis isolates (JEGX01.CN0001,JEGX01.CN0003,JEGXO1.CN0002,JEGX01.CN0019) and S.Typhimurium pattern of JPXX01.CN0001 were dominant patterns. Conclusion The prevalence of Salmonella from 2008 to 2009 showed distribution characteristics of sex,age and seasons.The numerous PFGE patterns of Salmonella showed diversity of these isolates and different clones existed in Beijing.     

An outbreak of human salmonellosis caused by ampicillin-resistant Salmonella enterica serovar Enteritidis PT13 in the Czech Republic

In summer 2004, an outbreak caused by Salmonella enterica serovar Enteritidis phage type 13 (S. Enteritidis PT13) was recorded in the Czech Republic. As well being a relatively rare phage type the strain was also ampicillin resistant. Outbreak (n=39) and pre-outbreak isolates (n=13) were characterized by pulsed-field gel electrophoresis (PFGE), beta-lactamase gene polymerase chain reaction and plasmid profile. The majority of outbreak isolates (n=37) were identical in XbaI PFGE profile, and two other outbreak isolates each differed from this profile by one or two fragments respectively. The pre-outbreak isolates were uniform in PFGE profile but distinct from the outbreak strain. Ampicillin resistance was confirmed to be encoded by the blaTEM gene located on the TnA transposon. This gene was readily transferable to a S. Enteritidis recipient strain and was associated with the transfer of a 200-kb plasmid. Our results indicate that all S. Enteritidis PT13 tested from 2004 belonged to a single outbreak strain which prior to 2004 had not been recognized in the Czech Republic.     

Relationship of pulsed-field profiles with key phage types of Salmonella enterica serotype Enteritidis in Europe: results of an international multi-centre study

Salmonella is one of the most common causes of foodborne infection in Europe with Salmonella enterica serovar Enteritidis (S. Enteritidis) being the most commonly identified serovar. The predominant phage type for S. Enteritidis is phage type (PT) 4, although PT 8 has increased in incidence. Within these phage types, pulsed-field gel electrophoresis (PFGE) provides a method of further subdivision. The international project, Salm-gene, was established in 2001 to develop a database of PFGE profiles within nine European countries and to establish criteria for real-time pattern recognition. It uses DNA fingerprints of salmonellas to investigate outbreaks and to evaluate trends and emerging issues of foodborne infection within Europe. The Salm-gene database contains details of about 11 700 S. Enteritidis isolates, demonstrating more than 65 unique PFGE profiles. The clonal nature of S. Enteritidis is evidenced by the high similarity and distribution of PFGE profiles. Over 56% (6603/11 716) of the submitted isolates of several different phage types were profile SENTXB.0001, although this profile is most closely associated with PT 4. The next most common profiles, SENTXB.0002 and SENTXB.0005, were closely associated with PT 8 and PT 21 respectively. Studies to investigate the relationship of profile types with outbreaks and possible vehicles of infection suggest that the incidence of PFGE profile SENTXB.0002, and thus PT 8, in some countries may be due to importation of foods or food production animals from Eastern Europe, where PT 8 is amongst the most frequently identified phage types. Collation of subtyping data, especially in the commonly recognized phage types, is necessary in order to evaluate trends and emerging issues in salmonella infection.     

Antimicrobial susceptibility and phage types of Salmonella enteritidis strains isolated in the Lublin area

The study aimed at specifying the value of two traditional methods of typing, using the collection of 241 strains of Salmonella Enteritidis isolated from people and animals in the Lublin area in 1994-1995 from the occasional cases of infections. There were 8 phage types identified among the examined strains. Phage types PT 6 (40.24% of strains) and PT 7 (29.46%) were the most numerous ones. Salmonella Enteritidis was numbered among 38 profiles on the basis of the analysis of resistance to 15 antimicrobial agents. It was found that nitrofurantoin had the lowest efficacy in vitro in relation to the examined collection of Salmonella isolates. High percentage of strains were characterized by lack of susceptibility to streptomycin, neomycin, cefixime, tetracycline and canamycine. While analyzing the profiles of resistance to chemiotherapeutics and the expression of phage type of the examined strains it was observed that only 14.1% of all strains showing resistance to nitrofurantoin represented at the same time phage type PT 6, whereas 10.8% of strains belonging to the same resistance profile indicated PT 7 phage type. In correlated analysis of resistance to chemiotherapeutics and phage type expression of the examined collection of 241 isolates of Salmonella Enteritidis, 18.3% of strains showed distinct and unique set of these two features, which can be used in epidemiological investigations for the preliminary characterization of the bacterial population.     

肠炎沙门菌食物中毒的病原学检测分析

目的 对一起食物中毒事件进行病原学分析和流行病学调查,探讨其中毒原因、传染源及传播途径。方法 通过现场流行病学调查对数据资料进行Fisher确切概率检验,对患者肛拭子、剩余食品、原材料等28份样品进行实时荧光PCR检测及分离培养;对分离菌株进行生化鉴定和血清分型,用改良K-B法进行药敏试验,应用脉冲场凝胶电泳（PFGE）分型技术进行同源性分析。 结果 从可疑食品蛋糕和6个患者中共分离到7株肠炎沙门菌,生物学性状、血清型和药敏试验结果一致, PFGE条带聚类分析显示所有菌株属同一克隆株。结论 这是一起肠炎沙门菌污染引起的食物中毒事件。食品卫生监督部门应加强网购食品卫生管理,减少食物中毒的发生。     

A Comparison of Subtyping Methods for Differentiating Salmonella enterica Serovar Enteritidis Isolates Obtained from Food and Human Sources

PurposeTo evaluate the abilities of these subtyping methods, we distinguished Salmonella Enteritidis (S. Enteritidis) isolated from food products and human clinical samples between 2009 and 2010 in Seoul using five subtyping methods.MethodsWe determined the subtypes of 20 S. Enteritidis isolates from food and human sources using phage typing, antimicrobial susceptibility, pulsed-field gel electrophoresis (PFGE), repetitive sequence-based PCR (rep-PCR), and multilocus sequence typing (MLST).ResultsA total of 20 tested isolates were differentiated into six antimicrobial susceptibility patterns, three different phage types, four different PFGE profiles, seven rep-PCR patterns, and one MLST type. Food isolates were considerably more susceptible to antibiotics than human isolates. We were best able to discriminate among S. Enteritidis isolates using rep-PCR, and obtained the highest Simpson's diversity index of 0.82, whereas other methods produced indices that were less than 0.71. PFGE pattern appeared to be more related to antimicrobial resistance and phage types of S. Enteritidis isolates than rep-PCR. MLST revealed identical alleles in all isolates at all seven loci examined, indicating no resolution.ConclusionThe results of this study suggest that rep-PCR provided the best discriminatory power for phenotypically similar S. Enteritidis isolates of food and human origins, whereas the discriminatory ability of MLST may be problematic because of the high sequence conservation of the targeted genes.     

广东省2008－2009 年沙门菌监测

目的 了解广东省腹泻患者中沙门菌的感染及沙门菌暴发的情况以及沙门菌株的血清型别、耐药性和分子特征.方法 对纳入研究的腹泻病患者进行沙门菌的检测,对日常监测中分离到的菌株和暴发监测收集到的菌株进行血清分型、药物敏感试验和脉冲场凝胶电泳(PFGE)分型.结果 2008年共检测1922份粪便标本,分离到7l株沙门菌,阳性率为3.7%;2009年检测2110份粪便标本,分离到85株沙门菌,阳性检出率为4.0%;156株菌共分37种血清型,鼠伤寒和肠炎沙门菌居多;监测到10起由沙门菌污染引起的食物中毒事件,其中有4起由肠炎沙门菌引起,有3起由鼠伤寒沙门菌引起;发现1起疑似肠炎沙门菌暴发,并开展流行病学调查,结果提示4名病例中有2名病例是感染同一来源的肠炎沙门菌;229株沙门菌对头孢类和喹诺酮类抗菌药物敏感率达80%以上,59.3%是多重耐药沙门菌.结论 在广东省引起感染性腹泻和食物中毒的沙门菌主要为肠炎沙门菌和鼠伤寒沙门菌.

Abstract：

Objective To understand the infection of Salmonella (S.) in patients with diarrhea and outbreaks caused by Salmonella to identify the serotypes, resistance to antibiotics and PFGE types of the strains from the surveillance program in Guangdong province. Methods S. strains from patients with diarrhea were detected, and all the positive strains collected in routine and outbreak surveillance programs, were tested by serum agglutination, antibiotic susceptibility and PFGE.Results 71 S. strains were isolated from 1922 stool samples in 2008, with positive rate as 3.7%.85 S. strains were isolated from 2110 stool samples in 2009, with positive rate as 4.0%. All the 156 strains were divided into 37 serotypes, with S. serotype typhimurium and enteritidis as the most common serotypes. 10 incidents of food poisoning were detected, of which 4 were caused by enteritidis and 3 by typhimurium. A suspected outbreak by enteritidis was discovered and under epidemiological investigation. The findings indicated that 2 of the 4 patients from this outbreak were infected with identical enteritidis isolates. 80% of the 229 isolates were found susceptible to cephalosporins and quinoione and 59.3% of them were muitiresistant to the antibiotics. Conclusion S. enteritidis and S. typhimurium were the most common serotypes that caused infectious diarrhoea and food poisoning in Guangdong province.     

Fluorescent amplified fragment length polymorphism (FAFLP) based molecular epidemiology of hospital infections in a tertiary care setting in Hyderabad, India.

Bacterial isolates from respiratory and urinary tract infections in an Indian hospital setting were genotyped using FAFLP analysis. The 77 different isolates analyzed belonged to five genera namely Escherichia, Staphylococcus, Pseudomonas, Enterobacter and Pantoea. Before carrying out FAFLP analysis all the isolates were subjected to16S-23S ribosomal RNA-based species identification. Cluster analysis of FAFLP profiles of 77 isolates generated five groups corresponding to five bacterial genera that are used in the study. Further analyses of the dendrograms revealed efficient species and strain differentiation. Cluster analysis identified genetically distant clones among the clinical isolates of Staphylococcus aureus, two distinct genetic lineages among the Escherichia coli strains and a single cluster of closely related Pseudomonas aeruginosa isolates. Ribosomal spacer region amplification identified different species accurately but intraspecies discrimination could not be accomplished completely. Comparison of FAFLP profiles of our isolates, with a pilot database of validated strains, was very useful in identification and worked better in conjunction with dendrogram analysis.     

上海市肠炎沙门菌流行特征和分子分型研究

[目的]分析上海市2006—2007年肠炎沙门菌菌株,了解上海市肠炎沙门菌分子流行病学特征。[方法]回顾2002—2007年肠炎沙门菌食品株来源并与肠炎沙门菌腹泻株作耐药性比较;对2006—2007年全球沙门菌监测(GSS)病例和食品分离的肠炎沙门菌进行表型验证、药敏试验和脉冲凝胶电泳(PFGE)分析。[结果]2006—2007年肠炎沙门菌在本市非伤寒沙门菌病例中列首位,而80%的食品株源自禽及禽肉制品,食品株的抗生素耐药性高于腹泻株。2007年肠炎沙门菌腹泻株的耐药谱和2006年有较大差异。包括13株食品株在内共76株肠炎菌株可分为21种PFGE带型,遗传同源性接近80%,优势带型依次为3型(34株)、1型(12株)、2型(5株)和5型(5株),除2型外均发现有与腹泻株同型的食源株。2006和2007年的PFGE 1/2型病例分别为4例和12例。[结论]上海市肠炎沙门菌病例与食用污染的鸡肉等禽类制品有密切关系,PFGE 3型肠炎沙门菌是目前上海市肠炎沙门菌流行株的优势菌型,2007年发现由鹅肝传播的1/2型肠炎沙门菌可能是3型的变异株并有取代之成为流行菌株的趋势。开展对腹泻病例和食物链的综合监测和以实验室为主的实时分子分型检测能快速预警肠炎沙门菌散在爆发和追溯污染源。