The molecular epidemiological analysis of Shigella sonnei isolates from outbreak cases in Yokohama]

We conducted a molecular epidemiological analysis to evaluate the epidemiologic patterns of Shigella sonnei isolates from outbreak cases in Yokohama to clarify the epidemiologic linkages by contact tracing and sources of infection. In the first case (case A), all of the 6 isolates were the colicin 0 type and resistant to both streptomycin (SM) and trimethoprim/sulfamethoxazole (ST). The 5 isolates have plasmid of 230 kb. By RAPD analysis with 2 kinds of primers specific for Shigella, every 6 isolates showed the same pattern. But the DNA fingerprint analysis by PFGE that was performed according to 2 standardized restriction endonucleases revealed a discriminative pattern. However, the resemblance of all isolates, which was calculated by the UPGMA methods, was 0.90 or higher. In the second case (case B), all of the 14 isolates were the colicin 6 type and sensitive to 16 drugs. The serotype of 13 isolates was phase I. The 11 isolates have plasmids of 230 kb and 3 kb. The resemblance of all isolates, which was calculated by the UPGMA methods, was 0.89 or higher. The analysis with a combination of the plasmid, RAPD analysis and PFGE profiles may be effective in investigating detailed epidemiological features of isolates.     

Genetic and epidemiological relationships among Campylobacter isolates from humans

84 Campylobacter jejuni isolates from Swedish patients with domestic infection were characterized with pulsed-field gel electrophoresis (PFGE), and the subtype information considered in relation to epidemiological data. Based on pattern combinations from restriction cleavage with SmaI and SalI, 52 different PFGE types were identified. Types with an average pattern similarity of at least 82% and 63% were assembled in groups and clusters, respectively. The 2 largest clusters included 71% of the isolates. The distribution in time varied between different groups and clusters, where some were isolated sporadically during the whole period and others appeared more concentrated in time. Types in 1 cluster were significantly more often isolated in summer than other types in the study. Isolates from children showed lower pattern similarity to other isolates than isolates from adults. Sets of type and time related cases, possibly representing small outbreaks, were identified when indistinguishable PFGE patterns were found in isolates from temporally related cases. Our results indicate that although a large number of genotypes may be found among C. jejuni strains infecting humans, a large proportion of these may be genetically related, and that different genotypes may appear during different seasons and infect individuals of different ages.     

一起由空肠弯曲菌所致食源性疾病暴发事件的流行病学及病原学溯源分析

目的 对一起空肠弯曲菌所致的食源性疾病暴发事件进行流行病学及溯源分析。方法 对突发事件进行现场流行病学调查,采集粪便样本、环境涂抹样本、食品样本等进行快速PCR检测和病原菌分离。对分离菌株进行PFGE分子分型和全基因组测序分析,并进行药敏试验。结果 从7份病例样本和2份环境涂抹样本中分离出空肠弯曲菌。PFGE分析和cgMLST聚类结果表明其中3份病例样本和环境涂抹样本(蒸柜容器把手涂抹)分离的菌株克隆聚集成簇,ST型别为ST11105;另2份病例样本和环境涂抹样本(刀具砧板涂抹)分离的菌株属同一克隆株,ST型别为ST2031。还有2份病例样本分离的菌株ST型为ST11106和ST7533。药敏结果表明,分离株对四环素类和喹诺酮类耐药率较高,分别为77.8%、55.6%。基因组测序结果发现最多的耐药基因为bla_OXA-193,gyrA、tet(O),其中gyrA基因86位点发生T-I突变。分离株共获得168个毒力基因,涉及多种致病机理。结论 采用快速PCR法、PFGE分子分型技术、全基因组测序技术等可对突发事件进行快速、准确的溯源分析。     

O139群霍乱弧菌分子流行病学研究

目的分析2001-2006年广州地区霍乱暴发、散发事件及外环境监测中分离的O139群霍乱弧菌的致病相关基因型和PFGE型,追踪菌株的来源和变迁,探讨本地区O139群霍乱流行特点。方法采用多重PCR方法检测O139群菌株的4种致病相关基因,应用脉冲场凝胶电泳技术(PFGE)对菌株进行分子分型,采用软件Bio Numerics Version4.0对分型数据进行处理和分析。结果广州地区O139群菌株中存在2种致病相关基因型,即A型和C型,18株感染者相关菌株中,除1株外,均为致病相关基因A型;10株珠江水分离株均为致病相关基因C型。28株O139群霍乱弧菌分为20个不同的PFGE型,归为4个聚类群(Ⅰ、Ⅱ、Ⅲ、Ⅳ群)。珠江水中O139群菌株存在PFGE克隆型的多样性。O139群暴发中分离的菌株PFGE型相同或相近,O139群散发疫情中的病例分离株与部分暴发株也具有相同或相近的PFGE型。结论分子分型方法结合流行病学资料,可分析O139群霍乱菌株的流行特点,致病相关基因分型可代替噬菌体-生物分型来判断和区分O139群霍乱弧菌的流行株与非流行株,从而为霍乱的预防、控制和预警提供科学依据。     

Phenotypic and molecular characterization of serogroup C Neisseria meningitidis associated with an outbreak in Bahia,Brazil

Objective

To characterize meningococcal strains isolated from five cases of meningococcal disease (MD) associated with an outbreak in Trancoso – BA, occurred in October 2009. All cases, with the exception of a 39-year-old male, attended a dance party with approximately 1000 youngsters in a rural site.

Materials and methods

The epidemiological investigation was conducted by the Epidemiological Surveillance Service of Bahia State. Meningococcal strains were characterized at Adolfo Lutz Institute, the Brazilian National Reference Laboratory for Bacterial Meningitis by conventional techniques (serotype, serosubtype and antimicrobial susceptibility test) and by molecular methods (Pulsed-field gel electrophoresis – PFGE and Multilocus Sequence Typing – MLST).

Results

The PFGE showed 2 closely related restriction profiles, designated as PFGE types A and A1, having 92% relatedness to each other. MLST characterization showed both A and A1 clones were ST-3780, which belongs to the ST-103 complex. All isolates displayed the phenotype C:23:P1.5 and were susceptible to all antibiotics tested.

Conclusions

This is the first reported MD outbreak associated with serogroup C ST-103 complex in Brazil, as well as the party and illicit drug-use associated outbreak.     

Genetic profiling of Campylobacter jejuni strains from humans infected in Sweden or in Thailand, and from healthy Swedish chickens, studied by pulsed-field gel electrophoresis (PFGE)

The major objective of the study was to explore the genomic diversity between Campylobacter jejuni (C.jejuni) from different sources as a tool for epidemiological considerations. Subtyping was performed using pulsed-field gel electrophoresis (PFGE) and the enzyme used for cleavage was SmaI. Isolates originated from humans infected in Sweden (n=49) and Thailand (n=32) and from healthy Swedish chickens (n=51). Eight PFGE groups were formed in a dendrogram and 48% of the isolates belonged to 1 of these groups. In 2 PFGE groups, strains from humans infected in both Sweden and Thailand were represented. Four of the PFGE groups comprised high frequencies of strains from domestic human infection, as well as from healthy chickens. The PFGE pattern was also compared with the antibiotic resistance pattern in all the above-mentioned isolates. In conclusion, C.jejuni was a diverse group based on PFGE genotyping; about 24% of the clones from Swedish patients and healthy Swedish chickens were similar; and there was no correlation between the antibiotic resistance pattern and the PFGE profiling among the studied strains. Our findings are also in accordance with our hypothesis that there may be similarities between Swedish and Thai strains, which might support a theory of globally occurring C.jejuni.     

Molecular epidemiological analysis of Salmonella enterica serotype Derby infections in Hong Kong

OBJECTIVES: We aimed to study the antimicrobial susceptibilities and molecular epidemiology of Salmonella enterica serotype Derby, a unique and common salmonella serotype in Hong Kong. METHODS: Salmonella Derby strains isolated from stools of patients in a large general hospital in Hong Kong from 1989 to 1994 and from food samples isolated in the Public Health Laboratory were randomly selected and investigated for the antimicrobial susceptibilities by determining the minimal inhibitory concentrations of 19 antimicrobial agents and their relatedness using plasmid analysis, ribotyping, pulsed-field gel electrophoresis (PFGE) and total DNA fingerprinting. RESULTS: About 50% of the 127 isolates studied were susceptible to all the 19 antibiotics tested, although resistance to tetracycline (49%) and sulfamethoxazole (38%) was high. Only 12% did not harbour any detectable plasmids, while the rest contained plasmids in 51 profiles. There were two predominant clones, one comprising of 35% of isolates that could not be pulsotyped because discrete bands were not discernible after PFGE and another comprising 34% of isolates that could be pulsotyped. The remaining 31% belonged to a variety of types. CONCLUSIONS: Approximately 70% of S. Derby belonging to two clones were endemic in the community, while the remaining isolates belonged to a variety of types which were probably a result of sporadic infection. The sources of human infections were foods, since most isolates from foods also belonged to the two endemic clones. Typing of S. Derby isolates from other sources such as animals or the environment would help elucidate how foods were contaminated. PFGE might not be universally applicable to all salmonella strains.     

Serotypes and antimicrobial resistance of Campylobacter jejuni isolated from humans and animals in Thailand

We investigated the serotypes, distributions, and antimicrobial resistance of Campylobacter jejuni isolates from humans and animals as a source of infection in poultry between 2002 and 2003. A total of 50 C. jejuni isolates from humans and 29 C. jejuni isolates from poultry were studied for serotype using the Penner serotyping scheme and the drug susceptibilities of the isolates which were determined for 7 antimicrobial drugs using the disk diffusion method. Serotype B (10%), serotype E (8%) and serotype R (8%) were found in humans isolates, while serotype A (27%) was most freguently isolated from poultry, followed by serotype K (21%) and serotype C (13%). Resistance in human isolates to cephalothin was high (100%). Resistance to trimethoprim/sulfamethoxazole, ciprofloxacin, and nalidixic acid were observed in 90, 82 and 78% of isolates, respectively. Most of the isolates (88%) were susceptible to erythromycin. High levels of resistance to drugs (ciprofloxacin and nalidixic acid) were observed in the isolates from poultry. These results indicate the importance of poultry as a reservoir of C. jejuni infection in Thailand is limited. In addition, a high proportion of the isolates were resistant to antimicrobial drugs, particularly the quinolone group.     

Pulsed-field gel electrophoresis of Campylobacter jejuni and Campylobacter coli genomic DNA and its epidemiologic application

Genomic DNA from 12 different Campylobacter jejuni and 10 Campylobacter coli isolates was digested with SmaI and analyzed by pulsed-field gel electrophoresis (PFGE) and 16S rRNA hybridization studies. Although the two Campylobacter species displayed species-specific restriction and hybridization patterns, significant intraspecies differences were observed. Combined PFGE and hybridization pattern analysis failed to provide any more epidemiologic information than was obtained from PFGE restriction profiles alone. Therefore, results from these studies indicate that PFGE analysis of SmaI-restricted genomic DNA provides a reliable means of differentiating C. jejuni from C. coli and may represent a more practical approach to epidemiologic studies than combining conventional DNA restriction digestion pattern with RNA hybridization procedures.     

Clonal circulation of Salmonella enterica serotype Heidelberg in Italy?

Phenotypic and genetic characteristics of 21 strains of Salmonella serotype Heidelberg isolated in the years 1999-2003 from different sources in Italy were studied. Susceptibility patterns, plasmid analysis, and PFGE were used as epidemiological markers. Although non-homogeneous drug resistance patterns and plasmid profiles had been detected, PFGE patterns suggest the hypothesis of a nationwide clonal spread of this serotype associated with poultry.     

Serotypes, genotypes and drug resistance of group A streptococcal strains isolated in 1991, 2001 and 2002 in Tokushima Prefecture--comparison after decade

Sixty two strains of Group A streptococcus were isolated between August 2001 and June 2002. They were examined for T serotypes, pyrogenic exotoxin genes and resistance against antibiotics. The results were compared with those for 61 isolates of the same species collected between April and December 1991. Among the strains isolated in 1991, T4 was the dominant serotype (18 strains) followed by T12 and T1 (each 15 strains). These three serotypes represented 78.7% of the total number. In contrast, among the strains isolated in 2001 and 2002 T28 (13 strains) was the dominant serotype followed by T1 (12 strains) and T4 (7 strains). Examination of these isolates for pyrogenic exotoxin gene revealed that all carried speB and more than half of the strains isolated in 1991, 2001 and 2002 carried both speB and speC. Regarding the combination of T type and toxin genotype, out of the isolates in 1991 fifteen T4 strains were associated with B and C, eleven T12 types with B and C, and nine T1 strains with A and B, while out of the strains isolated in 2001 and 2002 eleven T28 strains were associated with B and C, six T1 strains with B and C, and both five T4 and T12 types with B and C. Sma I Pulsed-field gel electrophorasis analysis revealed that PFGE patterns of T4:spe B and C and T12:spe B and C strains in 2001 and 2002 are same as one of those in 1991, respectively. On the other hand, during the decade strains resistant to macrolide increased from 1 strain (1.6%) to 11 strains (17.7%) and those to tetracycline increased from 23 strains (37.7%) to 32 strains (41.6%). During the same period the incidence of multiple resistance increased from 9 strains (14.7%) to 14 strains (22.5%).     

Molecular, antibiogram and serological typing of Staphylococcus aureus isolates recovered from Al-Makased hospital in East Jerusalem

Staphylococcus aureus is a major cause of nosocomial infections and a risk in patients who have either undergone surgery or are on haemodialysis. The S. aureus infections in patients admitted to the clinical departments of Al-Makased Charitable Hospital in Jerusalem during a period of one year were investigated. Isolates included were from blood, surgical wounds, or other nonsuperficial sites. Of 63 isolates available for analysis, 46 (73.0%) expressed type 8 capsular polysaccharide; 13 (20.7%), type 5 capsular polysaccharide; only 4 isolates (6.3%) did not express type 5 or type 8 antibodies. The strains fitted in 7 different antibiogram types, with the type showing resistance only to penicillin and ampicillin prevalent in 34 out of 63 isolates (54.0%). Of the 12 methicillin-resistant S. aureus (MRSA) isolates (19.1%), 8(66.7%) possessed the type 8 capsule and 4(33.7%) the type 5 capsule. Pulsed-field gel electrophoresis of all isolates with the restriction-endonuclease enzymes Sma I revealed 34 patterns demonstrating that no single methicillin-sensitive S. aureus strain was endemic in the hospital. However, all MRSA isolates with a type 8 capsule showed identical PFGE patterns using the 2 restriction-endonuclease enzymes Sma I and SST II. Moreover, type 5 isolates showed identical patterns (one isolate differed from the rest with one band only). These data suggest and confirm the clonality of type 5 and type 8 MRSA isolates. Analysing the results of the capsular and antibiogram typing schemes in conjunction proved useful and suggested that such an analysis can be employed as a helpful epidemiological tool in hospitals with limited resources.     

A rare outbreak of food poisoning caused by Salmonella enterica serovar. Oranienburg--a case report and features of isolates

A rare food poisoning outbreak caused by S. Oranienburg occurred at a junior high school athletic meet in Kurashiki, Okayama, in September 2005. The 70 patients included junior high school students, teachers and other school staff, and their families. This bacillus was isolated from stools of two employees and another in catered sandwiches. The cause of the outbreak was determined by evidence and epidemiological investigation to be sandwiches served at the athletic meet. Biochemical features, sensitivity to 12 antibacterial agents, and DNA patterns determined by pulse field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic sequence PCR (ERIC2-PCR) agreed for all isolates from outbreak samples. Isolates resembled strains isolated from broilers and a patient stool in an outbreak involving cuttlefish chips from 1998 to 1999 in Okayama Prefecture. A number of differences in strains isolated from broilers, chicken appendix content, and feed were detected in 2004, so we concluded that few outbreaks of food poisoning occurred due to S. Oranienburg in Okayama, attention is required for food poisoning by S. Oranienburg in the future because the dissemination of S. Oranienburg strains showing different features has been confirmed.     

Epidemiological study on Staphylococcus epidermidis isolated from bloodstream and blood vessel catheter

An epidemiological study on 35 strains of Staphylococcus epidermidis was conducted in Juntendo University Hospital between 1994 and 1996. The strains were isolated from blood and blood vessel catheters. Three epidemiological markers; PFGE type (pulsed-field gel electrophoresis using SmaI), biotype by STAPHYOGRAM and antibiotype (antibiotic resistant pattern) were used. There were 12 types in PFGE type, 6 types in biotype and 7 types in antibiotype. 1. The predominant types were PFGE type A (57.1%), biotype 1 (62.9%), and antibiotype I (resistant for oxacillin, ampicillin and gentamicin; 34.3%) in Juntendo University Hospital. 2. The strains with antibiotic V-VII (resistant for over 6 antibiotics) showed only PFGE type A and B. All strains with PFGE type B showed biotype 4-6 (negative nitrate reduction strain). 3. The strains having PFGE type A and B were isolated from various patient wards. The strains showing PFGE type A and antibiotype I were isolated from the pediatric ward. 4. There was no strain with PFGE type C or D in 1996. 5. Three patients in whom S. epidermidis was frequently isolated for a few months had the same types of PFGE type, biotype as well as antibiotype.     

贵州省8例空肠弯曲菌病例的病原学诊断与分析

目的 对来自贵州省的8例空肠弯曲菌病疑似病例进行病原学诊断与分子流行病学特征分析,为病例的确诊和贵州省空肠弯曲菌病疫情的预防和控制提供科学依据。方法 对8例疑似病例粪便和血液标本进行细菌分离,采用传统方法和多重PCR方法对空肠弯曲菌可疑菌株进行鉴定,应用脉冲场凝胶电泳分型技术(PFGE)对空场弯曲菌分离株进行分析。结果 8例空肠弯曲菌病疑似病例标本均分离出空肠弯曲菌可疑菌株,PCR扩增出空肠弯曲菌预期大小的目的基因片段,PFGE显示8株菌经SamI酶切后产生7~10条DNA条带,聚类分析显示,8株菌株分为7个PFGE带型,8株菌的相似性>50%,其中GZ201004和GZ201005两株腹泻病例来源分离株相似性为100%,血培养血液标本分离株GZ201201与粪便标本分离株GZ201007相似性为66.7%。结论 8例空肠弯曲菌病疑似病例均检出空肠弯曲菌,PFGE显示GZ201004和GZ201005两株为同一来源,但8例病例来源菌株存在PFGE带型多态性,该研究结果为病例的确诊和疫情的预防和控制提供了科学依据。     

Waterborne Campylobacter jejuni epidemic in a Finnish hospital for rheumatic diseases

A waterborne Campylobacter jejuni outbreak in the Rheumatism Foundation Hospital in Heinola, Finland, in November-December 1986 is described. 32 patients and 62 members of the staff developed gastrointestinal symptoms. C. jejuni heat-stable serotype 45 was isolated from the faeces of 32 enteritis patients and from none of the controls. No other enteropathogens were found. Positive serological responses to C. jejuni acid extract antigen were detected by enzyme immunoassay in 34% of the symptomatic hospital patients, in 40% of the symptomatic staff members, and in 10% of the controls. The clinical course of the illness was mostly mild and self-limited. No striking progress in the arthritis symptoms of the patients was found after the outbreak. The hospital has its own water supply. C. jejuni of the same serotype as the epidemic strain was isolated from the water of the pipeline system. After a careful examination some aged components of the waterworks were found to be responsible for leaks that resulted in the contamination of the water.     

上海市汤卜逊沙门菌流行特征分析

目的研究上海市汤卜逊沙门菌暴发菌株的流行特征。方法调查和收集本地区在全球沙门菌监测(GSS)腹泻病例中分离的汤卜逊沙门菌散发和暴发病例的菌株,并经过系统表型鉴定和耐药性分析;脉冲凝胶电泳(PFGE)选用:XbaⅠ限制性内切酶,聚类软件选用BioNumerics4.0软件。结果2007年GSS分离汤卜逊沙门菌22株,在上海市非伤寒沙门菌型的确诊腹泻病例中排第3位,2007年黄浦区中心医院报告的8株集聚性腹泻病例分离的汤卜逊沙门菌对四环素、奥格门丁、氨苄西林、氯霉素、萘啶酸、磺胺异恶唑6种抗生素的耐药率均为100%,耐药谱明显高于其他散发病例菌株。20株腹泻株和2株食品被PFGE图谱分为15个带型,其中8株暴发菌株显示单一PFGE图谱,其余14个PFGE带型的菌株均仅有1株,分别来自汤卜逊沙门菌散发菌株(12株)和食品株(2株),菌株间的遗传相似度不高。结论2007年10月上海市黄浦区某工地发生的1起暴发病例是由在遗传上完全相同的汤卜逊沙门菌的多重耐药克隆株引起的,PFGE技术可以通过菌株之间的分子同源性关系来证实监测病例中存在的局部暴发病例。     

Molecular tracking of the lineage of strains of Vibrio cholerae O1 biotype El Tor associated with a cholera outbreak in Andaman and Nicobar Islands, India

A large outbreak of acute watery diarrhoea involving all age groups of mongoloid tribal aborigines occurred during October-November, 2002 in the Nancowry group of Andaman and Nicobar Islands in the Indian Ocean. Twenty-one of the 67 stool samples from 67 patients were positive for toxigenic Vibrio cholerae O1, serotype Ogawa biotype El Tor, which showed striking similarity in its antibiogram with some of the strains of V. cholerae O1 Serotype Ogawa biotype El Tor isolated in Kolkata. The Nancowry and Kolkata isolates were compared with molecular tools involving random amplified polymorphic DNA (RAPD) fingerprinting, ribotyping and pulsed-field gel electrophoresis (PFGE). RAPD fingerprinting and ribotyping techniques revealed that all the V. cholerae strains associated with the outbreak in these islands were clonal in nature and identical to a population of isolates obtained from Kolkata since 1993. PFGE could discriminate within these Kolkata isolates further and established that a particular subtype of this population reached the remote Nancowry islands and was responsible for the outbreak.     

Usefulness of pulsed-field gel electrophoresis in tracking two outbreaks of invasive meningococcal disease serogroup C in British Columbia

Two major outbreaks of invasive meningococcal disease serogroup C (IMD-C) were identified in British Columbia between 2000 and 2004. Pulsed-field gel electrophoresis (PFGE) and porA gene sequencing of all retained IMD-C isolates were used to assess correlations between genotypes and epidemiological patterns. PFGE patterns of IMD-C genotypes correlated with epidemiological patterns between 2000 and 2004 in British Columbia, and demonstrated that PFGE can identify outbreak-related cases. Both IMD-C outbreaks correlated with a respective PFGE pattern. PFGE analysis demonstrated that the 2004 British Columbia outbreak strain in men who have sex with men was closely related to the 2001 Abbotsford outbreak strain. PorA sequencing data indicated low diversity of class 1 outer membrane proteins in British Columbia, and did not correlate with epidemiological trends. There was a trend for outbreak-associated PFGE types to demonstrate higher case fatality rates.     

Molecular epidemiology of a multiresistant Pseudomonas aeruginosa outbreak in a paediatric intensive care unit.

After isolation of multiresistant (MR) Pseudomonas aeruginosa from 3 hospitalized patients in a paediatric intensive care unit (PICU), a prospective surveillance programme was established to detect infected and/or colonized patients in the hospital. Isolates were examined by means of outer membrane protein (OMP) profiles, serotyping and DNA genomic analysis using pulsed-field gel electrophoresis (PFGE). Fifty-five P. aeruginosa strains were isolated from 23 hospitalized patients during September and October 1997. The median hospital stay before isolation of P. aeruginosa was 8 d. PFGE demonstrated that the same clone infected 14 patients, 4 of whom were not hospitalized in the PICU. Susceptibility patterns and OMP profiles correlated with PFGE results in 37.8% and 36.4% of cases, respectively. Serotype O11 correlated with pattern A in 77% of cases and serotype O4 correlated with unrelated strains in 75% of cases but did not discriminate between outbreak and unrelated isolates. Extensive investigation of cultures failed to identify a reservoir of P. aeruginosa. PFGE was superior to OMP analysis and serotyping for discriminating between strains. The possible mode of acquisition for most of the patients infected with the same clone was cross-contamination.