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Elisabeth Hauser,
Alexander Mellmann,
Torsten Semmler,
Helen Stoeber,
Lothar H Wieler,
Helge Karch,
Nikole Kuebler, Angelika Fruth,
Dag Harmsen,
Thomas Weniger,
Erhard Tietze,
Herbert Schmidt
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ABSTRACT: Seventy-five food-associated Shiga toxin-producing Escherichia coli (STEC) were analyzed by molecular and phylogenetic methods to describe their pathogenic potential. The presence of the locus of proteolysis (LPA), the chromosomal island PAI I(CL3), and the autotransporter encoding gene sabA, were examined by PCR. Furthermore, the occupation of the chromosomal integration sites of the locus of enterocyte effacement (LEE), selC, pheU and pheV as well as the Stx-phage integration sites yehV, yecE, wrbA, z2577 and ssrA were analyzed. Moreover, the antibiotic resistance phenotypes of all STEC were determined.Multilocus sequence typing (MLST) was performed and sequence types (ST) as well as sequence type complexes (STC) were compared with 42 HUS-associated enterohemorrhagic E. coli (HUSEC) strains. Besides 59 STs and 4 STCs, three larger clusters were defined in this strain collection. Clusters A and C mostly consist of highly pathogenic eae-positive HUSEC strains and some related food-borne STEC. A member of a new O26 HUS-associated clone and the 2011 outbreak strain E. coli O104:H4 was found in group A. Cluster B comprises only eae-negative food-borne STEC as well as mainly eae-negative HUSEC. Although food-borne strains of cluster B were not clearly associated with disease, serotypes of important pathogens such as O91:H21 and O113:H21 were in this group and closely related to the food-borne strains.Clonal analysis demonstrated eight closely related genetic groups of food-borne STEC and HUSEC that shared the same ST and were similar in their virulence gene composition. These groups should be considered with respect to their potential for human infection.
Applied and environmental microbiology 02/2013; · 3.69 Impact Factor
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Martina Bielaszewska,
Alexander Mellmann,
Stefan Bletz,
Wenlan Zhang,
Robin Köck,
Annelene Kossow,
Rita Prager, Angelika Fruth,
Dorothea Orth-Höller,
Monika Marejková,
Stefano Morabito,
Alfredo Caprioli,
Denis Piérard,
Geraldine Smith,
Claire Jenkins,
Katarína Curová,
Helge Karch
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ABSTRACT: Background. Enterohemorrhagic Escherichia coli (EHEC) O26 cause diarrhea and hemolytic uremic syndrome (HUS). Strains harboring stx(1a) gene prevail, but strains with stx(2a) as the sole Shiga toxin-encoding gene are now emerging. The traits and virulence of the latter set of strains are unknown. We correlated stx genotypes of 272 EHEC O26 strains isolated in seven European countries between 1996 and 2012 with disease phenotypes. We determined phylogeny, clonal structure and plasmid gene profiles of the isolates and portray geographic and temporal distribution of the different subgroups.Methods. stx genotypes and plasmid genes were identified using PCR, phylogeny was assigned using multilocus sequence typing and clonal relatedness was established using pulsed-field gel electrophoresis.Results. Of the 272 EHEC O26 isolates 107 (39.3%), 139 (51.1%), and 26 (9.6%) possessed stx(1a), stx(2a), or both genes, respectively. Strains harboring stx(2a) only were significantly associated with HUS (OR, 14.2; 95% CI, 7.9-25.6; P<0.001) compared to other stx genotypes. The stx(2a)-harboring strains consist of two phylogenetically distinct groups defined by sequence types ST21 and ST29. The ST29 strains are highly conserved and correspond by plasmid genes to the new virulent clone of EHEC O26 that emerged in Germany in the 1990s. This new clone occurred in six of the seven countries and represented ∼50% of all stx(2a)-harboring EHEC O26 strains isolated between 1996 and 2012.Conclusions. A new highly virulent clone of EHEC O26 has emerged in Europe. Its reservoirs and sources warrant identification.
Clinical Infectious Diseases 02/2013; · 9.15 Impact Factor
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Muna Abu Sin,
Anja Takla,
Antje Flieger,
Rita Prager, Angelika Fruth,
Erhard Tietze,
Eckhart Fink,
Jutta Korte,
Susanne Schink,
Michael Höhle,
Tim Eckmanns
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ABSTRACT: Background. From May-July 2011, Germany experienced a large Shiga toxin-producing E. coli (STEC) O104:H4 outbreak. Our objective was to identify the prevalence of STEC O104:H4 carriers in households in highly affected areas, the rate of secondary household transmissions, and the duration of long-term shedding.Methods. In a cross-sectional study, we recruited case and control households to determine STEC household prevalence; we then conducted a prospective cohort study (≥2-persons households with ≥1 case) for rates of household transmission and shedding duration.Results. For part 1, we recruited 57 case households (62 cases and 93 household contacts) and 36 control households (89 household members). We only detected cases in previously known case households and identified 1 possible adult-to-adult household transmission. For part 2, we followed 14 households and 20 carriers. No secondary household transmission was detected in the prospective follow-up. The longest prolonged shedding lasted >7 months, however, median estimated shedding time was 10-14 days (95% CI: 0-33 days). Three carriers showed intermittent shedding.Conclusions. Prevalence of STEC O104:H4 carriers even in highly affected areas appears to be low. Despite prolonged shedding in some patients, secondary adult-to-adult household transmissions seem to be rare events in the post-diarrheal disease phase.
The Journal of Infectious Diseases 11/2012; · 6.41 Impact Factor
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ABSTRACT: In this study, the population structure, incidence, and potential sources of human infection caused by the d-tartrate-fermenting variant of Salmonella enterica serovar Paratyphi B [S. Paratyphi B (dT+)] was investigated. In Germany, the serovar is frequently isolated from broilers. Therefore, a selection of 108 epidemiologically unrelated S. enterica serovar Paratyphi B (dT+) strains isolated in Germany between 2002 and 2010 especially from humans, poultry/poultry meat, and reptiles was investigated by phenotypic and genotypic methods. Strains isolated from poultry and products thereof were strongly associated with multilocus sequence type ST28 and showed antimicrobial multiresistance profiles. Pulsed-field gel electrophoresis XbaI profiles were highly homogeneous, with only a few minor XbaI profile variants. All strains isolated from reptiles, except one, were strongly associated with ST88, another distantly related type. Most of the strains were susceptible to antimicrobial agents, and XbaI profiles were heterogeneous. Strains isolated from humans yielded seven sequence types (STs) clustering in three distantly related lineages. The first lineage, comprising five STs, represented mainly strains belonging to ST43 and ST149. The other two lineages were represented only by one ST each, ST28 and ST88. The relatedness of strains based on the pathogenicity gene repertoire (102 markers tested) was mostly in agreement with the multilocus sequence type. Because ST28 was frequently isolated from poultry but rarely in humans over the 9-year period investigated, overall, this study indicates that in Germany S. enterica serovar Paratyphi B (dT+) poses a health risk preferentially by contact with reptiles and, to a less extent, by exposure to poultry or poultry meat.
Applied and environmental microbiology 08/2012; 78(20):7347-57. · 3.69 Impact Factor
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ABSTRACT: One hundred and ten UTI Escherichia coli strains, from Ljubljana, Slovenia, were analyzed for antibiotic resistances, mobile DNA elements, serotype, and phylogenetic
origin. A high prevalence of drug resistance and multidrug resistance was found. Twenty-six percent of the isolates harbored
a class 1 integron, while a majority of the strains (56%) harbored rep sequences characteristic of F-like plasmids. int as well as rep sequences were found to be distributed in a random manner among strains of the four major phylogenetic groups indicating
that all groups have a similar tendency to acquire and maintain mobile genetic elements frequently associated with resistance
determinants.
Current Microbiology 04/2012; 53(2):158-162. · 1.82 Impact Factor
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ABSTRACT: Salmonella enterica serovar Infantis (Salmonella Infantis) is consistently isolated from broiler chickens, pigs, and humans worldwide. This study investigated 93 epidemiologically unrelated Salmonella Infantis strains isolated in Germany between 2005 and 2008 in respect to their transmission along the food chain. Various phenotypic and genotypic methods were applied, and the pathogenicity and resistance gene repertoire was determined. Phenotypically, 66% of the strains were susceptible to all 17 antimicrobials tested, while the others were almost all multidrug-resistant (two or more antimicrobial resistances), with different resistance profiles and preferentially isolated from broiler chickens. A number of phage types (PTs) were shared by strains from pigs, broiler chickens, and humans (predominated by PT 29). One, PT 1, was only detected in strains from pigs/pork and humans. Pulsed-field gel electrophoresis (PFGE) subdivided strains in seven different clusters, named A-G, consisting of 35 various XbaI profiles with coefficient of similarity values of 0.73-0.97. The majority of XbaI profiles were assigned to clusters A and C, and two predominant XbaI profiles were common in strains isolated from all sources investigated. Multi-locus sequence typing (MLST) analysis of selected strains representing the seven PFGE clusters revealed that they all belonged to ST32. The pathogenicity gene repertoire of 37 representative Salmonella Infantis strains analyzed by microarray was also identical. The resistance gene repertoire correlated perfectly with the phenotypic antimicrobial resistance profiles, and multidrug-resistant strains were associated with class 1 integrons. Overall, this study showed that two major closely related genotypes of Salmonella Infantis can transmit in Germany to humans through contaminated broiler meat or pork, and consequently presents a hazard for human health.
Foodborne Pathogens and Disease 03/2012; 9(4):352-60. · 2.26 Impact Factor
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ABSTRACT: A real-time multiplex PCR targeting stx(2), wzy(O104), and fliC(H4) of enterohemorrhagic Escherichia coli (EHEC) O104:H4 correctly determined the presence or absence of these genes in 253 EHEC isolates and enrichment cultures of stool samples from 132 patients. It is a rapid, sensitive, and specific tool for detecting EHEC O104:H4 in human stools.
Journal of clinical microbiology 02/2012; 50(5):1752-4. · 4.16 Impact Factor
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ABSTRACT: Shiga toxin-producing Escherichia coli (STEC) are the most virulent diarrheagenic E. coli known to date. They can be spread with alarming ease via food as exemplified by a large sprout-borne outbreak of STEC O104:H4 in 2011 that was centered in northern Germany and affected several countries. Effective control of such outbreaks is an important public health task and necessitates early outbreak detection, fast identification of the outbreak vehicle and immediate removal of the suspected food from the market, flanked by consumer advice and measures to prevent secondary spread.In our view, opportunities to improve control of STEC outbreaks lie in early clinical suspicion for STEC infection, timely diagnosis of all STEC at the serotype-level and integrating molecular subtyping information into surveillance systems. Furthermore, conducting analytical studies that supplement patients' imperfect food history recall and performing, as an investigative element, product tracebacks, are pivotal but underutilized tools for successful epidemiologic identification of the suspected vehicle in foodborne outbreaks. As a corollary, these tools are amenable to tailor microbiological testing of suspected food. Please see related article: http://www.biomedcentral.com/1741-7015/10/12.
BMC Medicine 02/2012; 10:11. · 6.03 Impact Factor
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Hendrik Wilking,
Udo Götsch,
Helma Meier,
Detlef Thiele,
Mona Askar,
Manuel Dehnert,
Christina Frank, Angelika Fruth,
Gérard Krause,
Rita Prager,
Klaus Stark,
Boris Böddinghaus,
Oswald Bellinger,
René Gottschalk
Emerging Infectious Diseases 01/2012; 18(1):169-70. · 6.79 Impact Factor
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ABSTRACT: Salmonella enterica serovar Derby (S. Derby) is one of the most prevalent serovars in pigs in Europe and in the U.S. and ranks among the 10 most frequently isolated serovars in humans. Therefore, a set of 82 epidemiologically unrelated S. Derby strains isolated between 2006 and 2008 from pigs, pork and humans in Germany was selected and investigated in respect to the transmission of clonal groups of the serovar along the food chain. Various phenotypic and genotypic methods were applied and the pathogenicity and resistance gene repertoire was determined. Phenotypically 72% of the strains were susceptible to all 17 antimicrobials tested while the others were monoresistant to tetracycline or multi-resistant with different resistance profiles. Four major clonal groups were identified based on PFGE, sequence data of the virulence genes sopA, sopB and sopD, VNTR-locus STTR5 and MLST revealing also the new sequence type ST774. Thirty different PFGE profiles were detected resulting in four clusters representing the four groups. The pathogenicity gene repertoire of 32 representative S. Derby strains analyzed by microarray showed six types with differences in the Salmonella pathogenicity islands, pathogenicity genes on smaller islets or prophages and fimbriae coding genes. The pathogenicity gene repertoire of the predominant types PAT DE1 and DE2 were most similar to the ones of S. Paratyphi B (dT+, O5-) and to a minor degree to S. Infantis and S. Virchow PATs. Overall this study showed that in Germany currently one major S. Derby clone is frequently isolated from pigs and humans. Contaminated pork was identified as one vehicle and consequently is a risk for human health. To prevent this serovar from entering the food chain, control measurements should be applied at the farm level.
International journal of food microbiology 08/2011; 151(2):141-9. · 3.01 Impact Factor
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Christina Frank,
Dirk Werber,
Jakob P Cramer,
Mona Askar,
Mirko Faber,
Matthias An Der Heiden,
Helen Bernard, Angelika Fruth,
Rita Prager,
Anke Spode, [......],
Sabine Jordan,
Markus J Kemper,
Per Follin,
Luise Müller,
M Sc,
Lisa A King,
Bettina Rosner,
Udo Buchholz,
Klaus Stark,
Gérard Krause
New England Journal of Medicine 07/2011; 365:10561771-80. · 53.30 Impact Factor
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Christina Frank,
Dirk Werber,
Jakob P Cramer,
Mona Askar,
Mirko Faber,
Matthias an der Heiden,
Helen Bernard, Angelika Fruth,
Rita Prager,
Anke Spode, [......],
Alexander Zoufaly,
Sabine Jordan,
Markus J Kemper,
Per Follin,
Luise Müller,
Lisa A King,
Bettina Rosner,
Udo Buchholz,
Klaus Stark,
Gérard Krause
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ABSTRACT: We describe an outbreak of gastroenteritis and the hemolytic-uremic syndrome caused by Shiga-toxin-producing Escherichia coli in Germany in May, June, and July, 2011. The consumption of sprouts was identified as the most likely vehicle of infection.
We analyzed data from reports in Germany of Shiga-toxin-producing E. coli gastroenteritis and the hemolytic-uremic syndrome and clinical information on patients presenting to Hamburg University Medical Center (HUMC). An outbreak case was defined as a reported case of the hemolytic-uremic syndrome or of gastroenteritis in a patient infected by Shiga-toxin-producing E. coli, serogroup O104 or serogroup unknown, with an onset of disease during the period from May 1 through July 4, 2011, in Germany.
A total of 3816 cases (including 54 deaths) were reported in Germany, 845 of which (22%) involved the hemolytic-uremic syndrome. The outbreak was centered in northern Germany and peaked around May 21 to 22. Most of the patients in whom the hemolytic-uremic syndrome developed were adults (88%; median age, 42 years), and women were overrepresented (68%). The estimated median incubation period was 8 days, with a median of 5 days from the onset of diarrhea to the development of the hemolytic-uremic syndrome. Among 59 patients prospectively followed at HUMC, the hemolytic-uremic syndrome developed in 12 (20%), with no significant differences according to sex or reported initial symptoms and signs. The outbreak strain was typed as an enteroaggregative Shiga-toxin-producing E. coli O104:H4, producing extended-spectrum beta-lactamase.
In this outbreak, caused by an unusual E. coli strain, cases of the hemolytic-uremic syndrome occurred predominantly in adults, with a preponderance of cases occurring in women. The hemolytic-uremic syndrome developed in more than 20% of the identified cases.
New England Journal of Medicine 06/2011; 365(19):1771-80. · 53.30 Impact Factor
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ABSTRACT: In an ongoing outbreak of haemolytic uraemic syndrome and bloody diarrhoea caused by a virulent Escherichia coli strain O104:H4 in Germany (with some cases elsewhere in Europe and North America), 810 cases of the syndrome and 39 deaths have occurred since the beginning of May, 2011. We analysed virulence profiles and relevant phenotypes of outbreak isolates recovered in our laboratory.
We analysed stool samples from 80 patients that had been submitted to the National Consulting Laboratory for Haemolytic Uraemic Syndrome in Münster, Germany, between May 23 and June 2, 2011. Isolates were screened with standard PCR for virulence genes of Shiga-toxin-producing E coli and a newly developed multiplex PCR for characteristic features of the outbreak strain (rfb(O104), fliC(H4), stx(2), and terD). Virulence profiles of the isolates were determined with PCR targeting typical virulence genes of Shiga-toxin-producing E coli and of other intestinal pathogenic E coli. We sequenced stx with Sanger sequencing and measured Shiga-toxin production, adherence to epithelial cells, and determined phylogeny and antimicrobial susceptibility.
All isolates were of the HUSEC041 clone (sequence type 678). All shared virulence profiles combining typical Shiga-toxin-producing E coli (stx(2), iha, lpf(O26), lpf(O113)) and enteroaggregative E coli (aggA, aggR, set1, pic, aap) loci and expressed phenotypes that define Shiga-toxin-producing E coli and enteroaggregative E coli, including production of Shiga toxing 2 and aggregative adherence to epithelial cells. Isolates additionally displayed an extended-spectrum β-lactamase phenotype absent in HUSEC041.
Augmented adherence of the strain to intestinal epithelium might facilitate systemic absorption of Shiga toxin and could explain the high progression to haemolytic uraemic syndrome. This outbreak demonstrates that blended virulence profiles in enteric pathogens, introduced into susceptible populations, can have extreme consequences for infected people.
German Federal Ministry of Education and Research, Network Zoonoses.
The Lancet Infectious Diseases 06/2011; 11(9):671-6. · 17.39 Impact Factor
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Ariane Liebchen,
Inga Benz,
Alexander Mellmann,
Helge Karch,
Tânia A T Gomes,
Denise Yamamoto,
Rodrigo T Hernandes,
Jorge Sampaio,
Suely C F Sampaio, Angelika Fruth,
M Alexander Schmidt
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ABSTRACT: Intestinal pathogenic Escherichia coli is a major causative agent of severe diarrhea. In this study the prevalences of different pathotypes among 702 E. coli isolates from Brazilian patients with diarrhea were determined by multiplex PCR. Interestingly, most strains were enteroaggregative E. coli (EAEC) strains, followed by atypical EPEC (ATEC) strains. Classical enteropathogenic E. coli (EPEC) strains were not detected.
Journal of clinical microbiology 06/2011; 49(6):2274-8. · 4.16 Impact Factor
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ABSTRACT: An analysis for stx(2) variants among the 2010 human stx(2)-positive Shiga toxin-producing Escherichia coli (STEC) strains from Germany collected at the National Reference Centre 1999-2008 revealed 0.6% to possess the recently described stx(2g) gene. Sequencing of the whole stx(2g) operons showed new alleles and pseudogenes. The further molecular, phenotypic, and phylogenetic comparison of 12 human stx(2g)-harbouring isolates with 12 stx(2g)-harbouring isolates from animals or environmental sources demonstrated that both groups are closely related, indicating the human infections as a potential zoonotic disease. Although originating from various different sources, the stx(2g)-containing strains belong to only 3 phylogenetic lineages, represented by 4 serovars belonging to 4 sequence types. In view of the huge diversity among other STEC, this suggests the emergence of the stx(2g) variant as a rather recent microevolutionary event. Interestingly, in the strains under investigation, Stx2g was not expressed. However, all of them contained the estIa gene which typically is associated with enterotoxin-producing E. coli and did express STIa. By this combination of virulence genes of different pathotypes of intestinal pathogenic E. coli, these strains represent a new, intermediate pathotype and emerging pathogens. Given a rising number of intermediate pathotypes becoming described among E. coli, a wider range of virulence markers should be included in the regular pathotype diagnostics.
International journal of medical microbiology: IJMM 03/2011; 301(3):181-91. · 2.80 Impact Factor
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ABSTRACT: Molecular analysis of Shiga toxin-producing Escherichia coli (STEC) from different sources is considered as a major approach to assess their risk potential. However, only limited data are available about the correlation of evolutionary relationship, the presence of major virulence factor genes and the putative risk of an STEC strain for human infection. In this study, we analysed the evolutionary relationship of 136 pathogenic E. coli strains from human, animal and food sources by multi-locus sequence typing (MLST) and molecular subtyping of their Shiga toxin (stx) and intimin (eae) genes. Moreover, the distribution of three type III effector genes, encoded within the locus of enterocyte effacement (LEE), and 16 effector genes, which are encoded outside the LEE, was analysed. One hundred and five strains from different sources harboured 5-15 of the analysed non-LEE-encoded effector genes. In 101 of these strains, the LEE genes eae, map, espF and espG were present simultaneously. Thirty-one isolates deriving mainly from food and patients suffering from haemolytic uraemic syndrome (HUS) were eae-negative and did not carry any of the analysed effector genes. By combination of MLST and virulence gene data, we defined five genetic clusters. Within these clusters a clear-cut affiliation of particular sequence types and the occurrence of certain effector genes was observed. However, in contrast to other studies, a significant correlation between the amount and type of effector genes and the risk to cause HUS could not be demonstrated.
Environmental Microbiology 09/2010; 13(2):439-52. · 5.84 Impact Factor
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Viktor Merkel,
Barbara Ohder,
Martina Bielaszewska,
Wenlan Zhang, Angelika Fruth,
Christian Menge,
Erika Borrmann,
Barbara Middendorf,
Johannes Müthing,
Helge Karch,
Alexander Mellmann
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ABSTRACT: eibG in Shiga toxin-producing Escherichia coli (STEC) O91 encodes a protein (EibG) which binds human immunoglobulins G and A and contributes to bacterial chain-like adherence to human epithelial cells. We investigated the prevalence of eibG among STEC, the phylogeny of eibG, and eibG allelic variations and their impact on the adherence phenotype. eibG was found in 15.0% of 240 eae-negative STEC strains but in none of 157 eae-positive STEC strains. The 36 eibG-positive STEC strains belonged to 14 serotypes and to eight multilocus sequence types (STs), with serotype O91:H14/H(-) and ST33 being the most common. Sequences of the complete eibG gene (1,527 bp in size) from eibG-positive STEC resulted in 21 different alleles with 88.11% to 100% identity to the previously reported eibG sequence; they clustered into three eibG subtypes (eibG-alpha, eibG-beta, and eibG-gamma). Strains expressing EibG-alpha and EibG-beta displayed a mostly typical chain-like adherence pattern (CLAP), with formation of long chains on both human and bovine intestinal epithelial cells, whereas strains with EibG-gamma adhered in short chains, a pattern we termed atypical CLAP. The same adherence phenotypes were displayed by E. coli BL21(DE3) clones containing the respective eibG-alpha, eibG-beta, and eibG-gamma subtypes. We propose two possible evolutionary scenarios for eibG in STEC: a clonal development of eibG in strains with the same phylogenetic background or horizontal transfer of eibG between phylogenetically unrelated STEC strains.
Infection and immunity 08/2010; 78(8):3625-36. · 4.21 Impact Factor
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ABSTRACT: Salmonella enterica subsp. enterica serovar 4,[5],12:i:- is a monophasic variant of S. enterica serovar Typhimurium (antigenic formula 4,[5],12:i:1,2). Worldwide, especially in several European countries and the United States, it has been reported among the 10 most frequently isolated serovars in pigs and humans. In the study reported here, 148 strains of the monophasic serovar isolated from pigs, pork, and humans in 2006 and 2007 in Germany were characterized by various phenotypic and genotypic methods. This characterization was done in order to investigate their clonality, the prevalence of identical subtypes in pigs, pork, and humans, and the genetic relatedness to other S. enterica serovar Typhimurium subtypes in respect to the pathogenic and resistance gene repertoire. Two major clonal lineages of the monophasic serovar were detected which can be differentiated by their phage types and pulsed-field gel electrophoresis (PFGE) profiles. Seventy percent of the strains tested belonged to definite phage type DT193, and those strains were mainly assigned to PFGE cluster B. Nineteen percent of the strains were typed to phage type DT120 and of these 86% belonged to PFGE cluster A. Sixty-five percent of the isolates of both lineages carried core multiresistance to ampicillin, streptomycin, tetracycline, and sulfamethoxazole encoded by the genes bla(TEM1-like), strA-strB, tet(B), and sul2. No correlation to the source of isolation was observed in either lineage. Microarray analysis of 61 S. enterica serovar 4,[5],12:i:- and 20 S. enterica serovar Typhimurium isolates tested determining the presence or absence of 102 representative pathogenicity genes in Salmonella revealed no differences except minor variations in single strains within and between the serovars, e.g., by presence of the virulence plasmid in four strains. Overall the study indicates that in Germany S. enterica serovar 4,[5],12:i:- strains isolated from pig, pork, and human are highly related, showing their transmission along the food chain. Since the pathogenicity gene repertoire is highly similar to that of S. enterica serovar Typhimurium, it is essential that interventions are introduced at the farm level in order to limit human infection.
Applied and environmental microbiology 07/2010; 76(14):4601-10. · 3.69 Impact Factor
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ABSTRACT: The diversity and relatedness of 100 Shiga toxin-producing Escherichia coli O91 isolates from different patients were examined by multilocus sequence typing. We identified 10 specific sequence types (ST) and 4 distinct clonal groups. ST442 was significantly associated with hemolytic uremic syndrome.
Emerging Infectious Diseases 09/2009; 15(9):1474-7. · 6.79 Impact Factor
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ABSTRACT: Shiga toxin (Stx)-producing Escherichia coli (STEC) strains of serogroup O91 are the most common human pathogenic eae-negative STEC strains. To facilitate diagnosis and subtyping of these pathogens, we genotypically and phenotypically characterized 100 clinical STEC O91 isolates. Motile strains expressed flagellar antigens H8 (1 strain), H10 (2 strains), H14 (52 strains), and H21 (20 strains) or were H nontypeable (Hnt) (10 strains); 15 strains were nonmotile. All nonmotile and Hnt strains possessed the fliC gene encoding the flagellin subunit of the H14 antigen (fliC(H14)). Most STEC O91 strains possessed enterohemorrhagic E. coli hlyA and expressed an enterohemolytic phenotype. Among seven stx alleles identified, stx(2dact), encoding mucus- and elastase-activatable Stx2d, was present solely in STEC O91:H21, whereas most strains of the other serotypes possessed stx(1). Moreover, only STEC O91:H21 possessed the cdt-V cluster, encoding cytolethal distending toxin V; the toxin was regularly expressed and was lethal to human microvascular endothelial cells. Infection with STEC O91:H21 was associated with hemolytic-uremic syndrome (P = 0.0015), whereas strains of the other serotypes originated mostly in patients with nonbloody diarrhea. We conclude that STEC O91 clinical isolates belong to at least four lineages that differ by H antigens/fliC types, stx genotypes, and non-stx putative virulence factors, with accumulation of virulence determinants in the O91:H21 lineage. Isolation of STEC O91 from patients' stools on enterohemolysin agar and the rapid initial subtyping of these isolates using fliC genotyping facilitate the identification of these emerging pathogens in clinical and epidemiological studies and enable prediction of the risk of a severe clinical outcome.
Journal of clinical microbiology 05/2009; 47(7):2061-6. · 4.16 Impact Factor
