Cronobacter sakazakii continues to be isolated from ready-to-eat fresh and frozen produce, flours, dairy powders, cereals, nuts, and spices, in addition to the conventional sources of powdered infant formulae (PIF) and PIF production... more
Cronobacter sakazakii continues to be isolated from ready-to-eat fresh and frozen produce, flours, dairy powders, cereals, nuts, and spices, in addition to the conventional sources of powdered infant formulae (PIF) and PIF production environments. To understand the sequence diversity, phylogenetic relationship, and virulence of C. sakazakii originating from plant-origin foods, comparative molecular and genomic analyses, and zebrafish infection (ZI) studies were applied to 88 strains. Whole genome sequences of the strains were generated for detailed bioinformatic analysis. PCR analysis showed that all strains possessed a pESA3-like virulence plasmid similar to reference C. sakazakii clinical strain BAA-894. Core genome analysis confirmed a shared genomic backbone with other C. sakazakii strains from food, clinical and environmental strains. Emerging nucleotide diversity in these plant-origin strains was highlighted using single nucleotide polymorphic alleles in 2000 core genes. DNA h...
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Salmonella enterica subsp. enterica serovar Bovismorbificans has caused multiple outbreaks involving the consumption of produce, hummus, and processed meat products worldwide. To elucidate the intra-serovar genomic structure of S.... more
Salmonella enterica subsp. enterica serovar Bovismorbificans has caused multiple outbreaks involving the consumption of produce, hummus, and processed meat products worldwide. To elucidate the intra-serovar genomic structure of S. Bovismorbificans, a core-genome analysis with 2690 loci (based on 150 complete genomes representing Salmonella enterica serovars developed as part of this study) and a k-mer-binning based strategy were carried out on 95 whole genome sequencing (WGS) assemblies from Swiss, Canadian, and USA collections of S. Bovismorbificans strains from foodborne infections. Data mining of a digital DNA tiling array of legacy SARA and SARB strains was conducted to identify near-neighbors of S. Bovismorbificans. The core genome analysis and the k-mer-binning methods identified two polyphyletic clusters, each with emerging evolutionary properties. Four STs (2640, 142, 1499, and 377), which constituted the majority of the publicly available WGS datasets from >260 strains a...
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Cronobacter species are considered an opportunistic group of foodborne pathogenic bacteria capable of causing both intestinal and systemic human disease. This review describes common virulence themes shared among the seven Cronobacter... more
Cronobacter species are considered an opportunistic group of foodborne pathogenic bacteria capable of causing both intestinal and systemic human disease. This review describes common virulence themes shared among the seven Cronobacter species and describes multiple exoproteins secreted by Cronobacter, many of which are bacterial toxins that may play a role in human disease. The review will particularly concentrate on the virulence factors secreted by C. sakazakii, C. malonaticus, and C. turicensis, which are the primary human pathogens of interest. It has been discovered that various species-specific virulence factors adversely affect a wide range of eukaryotic cell processes including protein synthesis, cell division, and ion secretion. Many of these factors are toxins which have been shown to also modulate the host immune response. These factors are encoded on a variety of mobile genetic elements such as plasmids and transposons; this genomic plasticity implies ongoing re-assortme...
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Bacteria belonging to the genus Cronobacter have been recognized as causative agents of life-threatening systemic infections primarily in premature and low-birthweight neonates. Validation of putative bacterial virulence components as... more
Bacteria belonging to the genus Cronobacter have been recognized as causative agents of life-threatening systemic infections primarily in premature and low-birthweight neonates. Validation of putative bacterial virulence components as well as host factors potentially involved in the response to infection has been hampered in the past by the availability of suitable neonatal animal models. In the current study, the zebrafish embryo model was employed to study the interaction of the zinc metalloproteinase Zpx present in Cronobacter turicensis LMG 23827 , with the eukaryotic MMP-9, a proteinase that functions to cleave extracellular matrix gelatin and collagen. Cleavage and activation of the human recombinant pro-MMP-9 by zpx-expressing C. turicensis cells were demonstrated in vitro, and the presence and increase of the processed, active form of zebrafish pro-MMP-9 were shown in vivo. We provided evidence that Zpx induces the expression of the mmp-9 but also increases the levels of pro...
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Malonate utilization, an important differential trait, well recognized as being possessed by six of the seven species is thought to be largely absent in (Csak). The current study provides experimental evidence that confirms the presence... more
Malonate utilization, an important differential trait, well recognized as being possessed by six of the seven species is thought to be largely absent in (Csak). The current study provides experimental evidence that confirms the presence of a malonate utilization operon in 24 strains of sequence type (ST) 64, obtained from Europe, Middle East, China, and USA; it offers explanations regarding the genomic diversity and phylogenetic relatedness among these strains, and that of other strains. In this study, the presence of a malonate utilization operon in these strains was initially identified by DNA microarray analysis (MA) out of a pool of 347 strains obtained from various surveillance studies involving clinical, spices, milk powder sources and powdered infant formula production facilities in Ireland and Germany, and dried dairy powder manufacturing facilities in the USA. All ST64 strains tested could utilize malonate. Zebrafish embryo infection studies showed that ST64 strains are as ...
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Cronobacter (C.) sakazakii is an opportunistic pathogen and has been associated with serious infections with high mortality rates predominantly in pre-term, low-birth weight and/or immune compromised neonates and infants. Infections have... more
Cronobacter (C.) sakazakii is an opportunistic pathogen and has been associated with serious infections with high mortality rates predominantly in pre-term, low-birth weight and/or immune compromised neonates and infants. Infections have been epidemiologically linked to consumption of intrinsically and extrinsically contaminated lots of reconstituted powdered infant formula (PIF), thus contamination of such products is a challenging task for the PIF producing industry. We present the draft genome of C. sakazakii H322, a highly persistent sequence type (ST) 83, clonal complex (CC) 65, serotype O:7 strain obtained from a batch of non-released contaminated PIF product. The presence of this strain in the production environment was traced back more than 4 years. Whole genome sequencing (WGS) of this strain together with four more ST83 strains (PIF production environment-associated) confirmed a high degree of sequence homology among four of the five strains. Phylogenetic analysis using mi...
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The extent of the occurrence of the plasmid-encoded colistin resistance genes mcr-1 and mcr-2 among humans is currently sparsely studied in Western Europe. To determine the occurrence of MCR-producing Enterobacteriaceae in fecal samples... more
The extent of the occurrence of the plasmid-encoded colistin resistance genes mcr-1 and mcr-2 among humans is currently sparsely studied in Western Europe. To determine the occurrence of MCR-producing Enterobacteriaceae in fecal samples of healthy humans with high occupational exposure to food and primary care patients in Switzerland. Stool samples from 1091 healthy individuals and fecal swabs from 53 primary care patients were screened for polymyxin-resistant Enterobacteriaceae using LB agar containing 4 mg/L colistin. Minimal inhibitory concentrations (MICs) of colistin were determined for non-intrinsic colistin-resistant isolates. Isolates were screened by PCR for the presence of mcr-1 and mcr-2 genes. The fecal carriage rate of colistin resistant (MIC value >2 mg/l) Enterobacteriaceae was 1.5% for healthy people and 3.8% for primary care patients. Isolates included Hafnia alvei (n = 9), Escherichia coli (n = 3), Enterobacter cloacae (n = 4), Klebsiella pneumoniae (n = 1) and ...
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Cronobacter (previously known as Enterobacter sakazakii) is a genus of Gram-negative, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped bacteria of the family Enterobacteriaceae. These organisms cause a variety of... more
Cronobacter (previously known as Enterobacter sakazakii) is a genus of Gram-negative, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped bacteria of the family Enterobacteriaceae. These organisms cause a variety of illnesses such as meningitis, necrotizing enterocolitis, and septicemia in neonates and infants, and urinary tract, wound, abscesses or surgical site infections, septicemia, and pneumonia in adults. The total gene content of 379 strains of Cronobacter spp. and taxonomically-related isolates was determined using a recently reported DNA microarray. The Cronobacter microarray as a genotyping tool gives the global food safety community a rapid method to identify and capture the total genomic content of outbreak isolates for food safety, environmental, and clinical surveillance purposes. It was able to differentiate the seven Cronobacter species from one another and from non-Cronobacter species. The microarray was also able to cluster strains within each ...
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Here, we report the draft genome sequence of the lactose-negative, rifampin-resistant, Escherichia coli strain 26R 793. This isolate has been widely used in conjugation experiments as a general recipient strain.
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We present the draft genome of Escherichia coli S51, a colistin-resistant extended-spectrum β-lactamase-producing strain isolated in 2015 from raw chicken meat imported from Germany. Assembly and annotation of this draft genome resulted... more
We present the draft genome of Escherichia coli S51, a colistin-resistant extended-spectrum β-lactamase-producing strain isolated in 2015 from raw chicken meat imported from Germany. Assembly and annotation of this draft genome resulted in a 4,994,918-bp chromosome and revealed a chromosomally encoded mcr-1 gene responsible for the colistin resistance of the strain.
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Ready-to-eat (RTE) prepacked salads and fruit have been successfully marketed for the last decade in Switzerland and are increasingly important as a component of everyday diets. To determine whether extended-spectrum β-lactamase... more
Ready-to-eat (RTE) prepacked salads and fruit have been successfully marketed for the last decade in Switzerland and are increasingly important as a component of everyday diets. To determine whether extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae are present in RTE salads, fresh-cut fruit, and sprouts on the Swiss market, samples of 238 mixed and unmixed RTE produce from a large production plant and 23 sprout samples from two sprout farms were analyzed. Further, four samples from the production plant's recycled wash water, which is used for crop irrigation, were analyzed. Twelve (5%) of the 238 RTE products and one of the recycled wash water samples yielded ESBL-producing Enterobacteriaceae. Strain identification and PCR analysis of the blaESBL genes revealed Kluyvera ascorbata isolated from a tomato sample harboring a blaCTX-M-2-like gene; multidrug-resistant (MDR) Enterobacter cloacae detected in a chives sample imported from Spain harboring the clinically im...
Research Interests: Biology, Medicine, Multidisciplinary, Food Microbiology, Spain, and 13 moreBiological Sciences, Escherichia coli, Polymerase Chain Reaction, Switzerland, Fruit, Enterobacteriaceae, Prevalence, Fast Foods, Food Contamination, Serratia, Medicine and Health Sciences, Beta Lactamases, and Enterobacter cloacae
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Cronobacter sakazakii is a food-borne pathogenic bacterium that may cause severe illness in neonates and the elderly. We present the genome sequence of a rare strain (ST40, CC45), commonly found in multiple food processing facilities and... more
Cronobacter sakazakii is a food-borne pathogenic bacterium that may cause severe illness in neonates and the elderly. We present the genome sequence of a rare strain (ST40, CC45), commonly found in multiple food processing facilities and in powdered infant formula and only indicted in a single clinical case.
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Human isolates of Salmonella enterica serovars Hadar, Kentucky, Virchow, Schwarzengrund, and the monophasic variant of S. Typhimurium, Salmonella enterica subsp. enterica serovar 4,5,12:i:- were examined for mutations within the quinolone... more
Human isolates of Salmonella enterica serovars Hadar, Kentucky, Virchow, Schwarzengrund, and the monophasic variant of S. Typhimurium, Salmonella enterica subsp. enterica serovar 4,5,12:i:- were examined for mutations within the quinolone resistance target genes gyrA, gyrB, parC, and parE and for plasmid-mediated resistance genes. Differences were observed among the serovars. A novel variant of qnrD, qnrD2, was detected in an S. Hadar isolate.
Research Interests: Microbiology, Medical Microbiology, Biology, Medicine, Humans, and 14 moreSwitzerland, Plasmids, Quinolones, Salmonella, Anti-Bacterial Agents, Dna Gyrase, Microbial Sensitivity Tests, Base Sequence, Medicine and Health Sciences, Serotype, Nalidixic acid, Salmonella enterica, Pharmacology and pharmaceutical sciences, and Serogroup
We report the draft genome sequence of Enterobacter helveticus strain LMG 23733, isolated from fruit powder. The draft genome assembly for E. helveticus strain LMG 23733 has a size of 4,635,476 bp and a G+C content of 55.9%.
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Extended-spectrum β-lactamase (ESBL)-encoding genes are frequently mapped to plasmids, yet few of these structures have been characterized at the molecular level, to date. Eighty-seven ESBL-producing Escherichia coli were isolated from... more
Extended-spectrum β-lactamase (ESBL)-encoding genes are frequently mapped to plasmids, yet few of these structures have been characterized at the molecular level, to date. Eighty-seven ESBL-producing Escherichia coli were isolated from fecal samples of food-producing animals and healthy humans in Switzerland from 2009 to 2011. Plasmid DNA of all isolates was purified. Broth mating assays were carried out individually for 32 isolates to determine if the ESBL marker could be transferred by conjugation. The plasmid sizes were determined by S1-nuclease pulsed-field gel electrophoresis (PFGE) and the plasmids were typed by PCR-based replicon typing. Susceptibility tests by disk diffusion followed with a re-analysis S1-nuclease PFGE and PCRs were performed to confirm plasmid transfer. Microarray was performed to detect additional antibiotic resistance markers and multi-locus sequence typing was also performed in selected donor strains. The phylotypes were identified by triplex PCR. About ...
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We report the draft genome sequences of the Enterobacter pulveris strains 601/05(T) (=LMG24057(T) =DSM19144(T)) and 1160/04 (=LMG24058 =DSM19146), isolated from fruit powder. The genome assemblies for the E. pulveris type strain,... more
We report the draft genome sequences of the Enterobacter pulveris strains 601/05(T) (=LMG24057(T) =DSM19144(T)) and 1160/04 (=LMG24058 =DSM19146), isolated from fruit powder. The genome assemblies for the E. pulveris type strain, LMG24057, and strain LMG24058 have sizes of 4,708,624 and 4,811,103 bp and G+C contents of 56.6% and 56.5%, respectively.
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Research Interests: Microbiology, Medical Microbiology, Fluorescence Microscopy, Biology, Medicine, and 15 moreColonization, FISH, Colonisation, Maize, Habitat, Bacteria, Cluster Analysis, Cronobacter, Enterobacteriaceae, Green Fluorescent Protein, Confocal Laser Scanning Microscopy, Lycopersicon esculentum, Cronobacter Sakazakii, Molecular Sequence Data, and Case fatality rate
Research Interests: Microbiology, Primary Health Care, Medicine, Antibiotic Resistance, Biological Sciences, and 15 moreHumans, Female, Male, Cephalosporins, Enterobacteriaceae, Antibiotics, Aged, Middle Aged, Adult, Feces, Cross Sectional Studies, Beta Lactamases, microbial drug resistance, Carriage, and Medical and Health Sciences
Research Interests: Microbiology, Biology, Industrial Biotechnology, Medicine, Food Microbiology, and 11 moreSequence alignment, Polymerase Chain Reaction, Species identification, Cronobacter, Enterobacteriaceae, Food Sciences, Species Specificity, Base Sequence, Medicine and Health Sciences, Epidemiologic Studies, and Molecular Sequence Data
Research Interests: Microbiology, Comparative Genomics, Biology, Industrial Biotechnology, Medicine, and 13 moreFood Microbiology, Lipopolysaccharide, Cluster Analysis, Cronobacter, Enterobacteriaceae, Hierarchical Clustering, Food Sciences, Indexation, Species Specificity, Open Reading Frame, Medicine and Health Sciences, Comparative Genomic Hybridization, and Cronobacter Sakazakii
Research Interests: Engineering, Microbiology, Biology, Medicine, Diarrhea, and 15 moreBiological Sciences, Humans, Mutation, Bacteria, Polymerase Chain Reaction, Phenotype, Anti-Bacterial Agents, Efflux, Dna Gyrase, Microbial Sensitivity Tests, Medicine and Health Sciences, Virulence Factors, Yersinia Enterocolitica, Nalidixic acid, and Medical and Health Sciences
Background Cronobacter spp. are opportunistic pathogens that can cause septicemia and infections of the central nervous system primarily in premature, low-birth weight and/or immune-compromised neonates. Serum resistance is a crucial... more
Background Cronobacter spp. are opportunistic pathogens that can cause septicemia and infections of the central nervous system primarily in premature, low-birth weight and/or immune-compromised neonates. Serum resistance is a crucial virulence factor for the development of systemic infections, including bacteremia. It was the aim of the current study to identify genes involved in serum tolerance in a selected Cronobacter sakazakii strain of clinical origin. Results Screening of 2749 random transposon knock out mutants of a C. sakazakii ES 5 library for modified serum tolerance (compared to wild type) revealed 10 mutants showing significantly increased/reduced resistance to serum killing. Identification of the affected sites in mutants displaying reduced serum resistance revealed genes encoding for surface and membrane proteins as well as regulatory elements or chaperones. By this approach, the involvement of the yet undescribed Wzy_C superfamily domain containing coding region in se...
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Background Members of the genus Cronobacter are causes of rare but severe illness in neonates and preterm infants following the ingestion of contaminated infant formula. Seven species have been described and two of the species genomes... more
Background Members of the genus Cronobacter are causes of rare but severe illness in neonates and preterm infants following the ingestion of contaminated infant formula. Seven species have been described and two of the species genomes were subsequently published. In this study, we performed comparative genomics on eight strains of Cronobacter, including six that we sequenced (representing six of the seven species) and two previously published, closed genomes. Results We identified and characterized the features associated with the core and pan genome of the genus Cronobacter in an attempt to understand the evolution of these bacteria and the genetic content of each species. We identified 84 genomic regions that are present in two or more Cronobacter genomes, along with 45 unique genomic regions. Many potentially horizontally transferred genes, such as lysogenic prophages, were also identified. Most notable among these were several type six secretion system gene clusters, transposons...
Research Interests: Genetics, Genomics, Molecular Evolution, Comparative Genomics, Biology, and 14 moreMedicine, Food Microbiology, Biological Sciences, Virulence, Phylogeny, Molecular Phylogenetics and Evolution, Genome, Cronobacter, Species Specificity, Mobile Genetic Elements, Medicine and Health Sciences, Prophage, Molecular Sequence Data, and Medical and Health Sciences
Re-examination of the taxonomic status of Enterobacter helveticus, Enterobacter pulveris and Enterobacter turicensis as members of the genus Cronobacter and their reclassification in the genera Franconibacter gen. nov. and Siccibacter gen. nov. as Franconibacter helveticus comb. nov., Franconibac...more
Recently, a taxonomical re-evaluation of the genus Enterobacter, based on multi-locus sequence typing (MLST) analysis, has led to the proposal that the species Enterobacter pulveris, Enterobacter helveticus and Enterobacter turicensis... more
Recently, a taxonomical re-evaluation of the genus Enterobacter, based on multi-locus sequence typing (MLST) analysis, has led to the proposal that the species Enterobacter pulveris, Enterobacter helveticus and Enterobacter turicensis should be reclassified as novel species of the genus Cronobacter. In the present work, new genome-scale analyses, including average nucleotide identity, genome-scale phylogeny and k-mer analysis, coupled with previously reported DNA-DNA hybridization values and biochemical characterization strongly indicate that these three species of the genus Enterobacter are not members of the genus Cronobacter, nor do they belong to the re-evaluated genus Enterobacter. Furthermore, data from this polyphasic study indicated that all three species constitute two new genera. We propose reclassifying Enterobacter pulveris and Enterobacter helveticus in the genus Franconibacter gen. nov. as Franconibacter pulveris comb. nov. (type strain 601/05(T) = LMG 24057(T) = DSM 1...
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The recent identification of Enterobacteriaceae harbouring the plasmid-mediated transferable colistin resistance mcr-1 gene is of great concern to public health (1-4).….
Research Interests: Microbiology, Medical Microbiology, Biology, Rivers, Medicine, and 15 moreGene expression, Humans, Switzerland, Enterobacteriaceae, Plasmids, Vegetables, Colistin, Public Health Surveillance, Beta Lactams, McR, Microbial Sensitivity Tests, Water Microbiology, Plasmid, Beta Lactamases, and Pharmacology and pharmaceutical sciences
Research Interests: Multidisciplinary, Antibiotic Resistance, Animal Husbandry, Genetic Diversity, Resistance, and 14 moreAnimals, Applied Environmental Microbiology, Bacteria, Polymerase Chain Reaction, Switzerland, Prevalence, Anti-Bacterial Agents, POULTRY DISEASES, Chickens, Microbial Sensitivity Tests, Genetic variation, Campylobacter jejuni, Campylobacter coli, and Flagellin
ABSTRACT
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Research Interests: Water, Molecular Biology, Dairy Science, Culture, Animal Production, and 17 moreFood Microbiology, real time PCR, Raw materials, Animals, Bacteria, Polymerase Chain Reaction, Switzerland, Water Activity, Milk products, Real Time, Cheese, Prevalence, Food Contamination, Food Sciences, Raw Milk, Microspheres, and Hydrogen-Ion Concentration
ABSTRACT Cronobacter spp. (former Enterobacter sakazakii) are occasional contaminants of powdered infant formula (PIF) and have been implicated in rare cases of neonatal infections. Surveys on the prevalence of these organisms and/or... more
ABSTRACT Cronobacter spp. (former Enterobacter sakazakii) are occasional contaminants of powdered infant formula (PIF) and have been implicated in rare cases of neonatal infections. Surveys on the prevalence of these organisms and/or contamination routes during the processing of the infant formula are of importance to the manufacturers in order to reduce the level of contamination of these products. Increasing customer awareness on possible contamination of other milk powder based products intended for consumption by (older) infants posed the question about the presence of Enterobacteriaceae and especially Cronobacter spp. in products other than PIF e. g. milk concentrate (intermediate) and milk powder, both added to a variety of infant foods. It was the aim of this study to create data on the prevalence of Enterobacteriaceae and possible epidemiologic correlation of Cronobacter spp. in raw milk, milk concentrate and milk powder obtained from a Swiss milk powder production facility (2 production sites). A total of 100 raw milk samples, 91 milk concentrate samples and 172 milk powder samples were collected and tested for the presence of Enterobacteriaceae including Cronobacter spp. by cultural means. Subsets of isolates from each sample category were selected for further molecular identification and subtyping analysis. A variety of members of the Enterobacteriaceae family were observed in all types of samples, whereas Cronobacter spp. was isolated from milk powder only. Subtyping revealed a relatively high degree of heterogeneity among Cronobacter spp. isolates from both production sites suggesting continuous entry and dissemination of organisms from the production environment into the products.
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Randomly amplified polymorphic DNA (RAPD) assay was used for epidemiological subtyping of B. cereus and B. lentus. Within 25 isolates of B. cereus up to 22 strain types could be determined when five primers were used. RAPD patterns, which... more
Randomly amplified polymorphic DNA (RAPD) assay was used for epidemiological subtyping of B. cereus and B. lentus. Within 25 isolates of B. cereus up to 22 strain types could be determined when five primers were used. RAPD patterns, which were found in three B. lentus strains, clearly differed form those of B. cereus. The RAPD technique proved to be an effective tool for the characterization of B. cereus strains.
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In the past 25 years, Listeria monocytogenes has become increasingly important as a food-associated pathogen. Most European Union countries have an annual incidence of human listeriosis of between two and ten reported cases per million.... more
In the past 25 years, Listeria monocytogenes has become increasingly important as a food-associated pathogen. Most European Union countries have an annual incidence of human listeriosis of between two and ten reported cases per million. Because of its high case fatality rate, listeriosis ranks among the most frequent causes of death due to food-borne illness. Listeria monocytogenes infections are responsible for the highest hospitalisation rates (91%) amongst known food-borne pathogens and have been linked to sporadic episodes and large outbreaks of human illness worldwide. The ability to persist in food-processing environments and multiply under refrigeration temperatures makes L. monocytogenes a significant threat to public health. Listeria monocytogenes contamination is one of the leading microbiological causes of food recalls, mainly of meat, poultry, seafood and dairy products. Prevention and control measures are based on hazard analysis and critical control point programmes throughout the food industry, and on specific recommendations for high-risk groups. Understanding how these micro-organisms adapt their cellular physiology to overcome stress is important in controlling L. monocytogenes in food environments.
Research Interests: Food Safety, European Union, Public Health, Food Processing, Food Microbiology, and 14 moreVirulence, Disease Outbreaks, Humans, Animals, Listeria monocytogenes, Hygiene, Food Industry, Infection prevention and control, Listeriosis, Dairy Products, Food Contamination, Veterinary Sciences, Food Processing Industry, and Hazard Analysis and Critical Control Point
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A total of 42 Shiga toxin-producing (STEC) strains from slaughtered healthy cattle in Switzerland were characterized by phenotypic and genotypic traits.The 42 sorbitol-positive, non-O157 STEC strains belonged to 26 O:H serotypes... more
A total of 42 Shiga toxin-producing (STEC) strains from slaughtered healthy cattle in Switzerland were characterized by phenotypic and genotypic traits.The 42 sorbitol-positive, non-O157 STEC strains belonged to 26 O:H serotypes (including eight new serotypes) with four serotypes (O103:H2, O113:H4, O116:H-, ONT:H-) accounting for 38.1% of strains. Out of 16 serotypes previously found in human STEC (71% of strains), nine serotypes (38% of strains) were serotypes that have been associated with hemolytic–uremic syndrome (HUS). Polymerase chain reaction (PCR) analysis showed that 18 (43%) strains carried the stx1 gene, 20 strains (48%) had the stx2 gene, and four (9%) strains had both stx1 and stx2 genes. Of strains encoding for stx2 variants, 63% were positive for stx2 subtype. Enterohemolysin (ehxA), intimin (eae), STEC autoagglutinating adhesin (saa) were detected in 17%, 21%, and 19% of the strains, respectively. Amongst the seven intimin-positive strains, one possessed intimin type β1 (O5:H-), one intimin γ1 (O145:H), one intimin γ2/θ, (O111:H21), and four intimin ɛ (O103:H2).The strains belonged to 29 serovirotypes (association between serotypes and virulence factors). O103:H2 stx1eae-ɛ ehxA, O116:H- stx2, and ONT:H- stx2c were the most common accounting for 29% of the strains. Only one strain (2.4%) of serovirotype O145:H- stx1stx2eae-γ1ehxA showed a pattern of highly virulent human strains. This is the first study providing characterization data of bovine non-O157 STEC in Switzerland, and underlining the importance of the determination of virulence factors (including intimin types) in addition to serotypes to assess the potential pathogenicity of these strains for humans.
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Research Interests: Multidisciplinary, Antibiotic Resistance, Animal Husbandry, Genetic Diversity, Resistance, and 14 moreAnimals, Applied Environmental Microbiology, Bacteria, Polymerase Chain Reaction, Switzerland, Prevalence, Anti-Bacterial Agents, POULTRY DISEASES, Chickens, Microbial Sensitivity Tests, Genetic variation, Campylobacter jejuni, Campylobacter coli, and Flagellin
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During the summer of 2013, an increase of Salmonella enterica ssp. enterica serovar Szentes isolates from human clinical cases was registered by the Swiss National Centre for Enteropathogenic Bacteria and Listeria. In the course of the... more
During the summer of 2013, an increase of Salmonella enterica ssp. enterica serovar Szentes isolates from human clinical cases was registered by the Swiss National Centre for Enteropathogenic Bacteria and Listeria. In the course of the ensuing 9 months, 18 isolates originating from 13 patients and from one food sample were collected. Of the 13 human cases, 10 (77%) were female. The patients' ages ranged from 27 to 83 years (median age 49 years). Pulsed-field gel electrophoresis (PFGE) performed with XbaI, and multilocus sequence typing (MLST) were used to type the strains. PFGE as well as MLST showed the strains as indistinguishable. The PFGE pattern and MLST sequence type (ST427) were identical to those of Salmonella enterica serovar Szentes isolated in previous years (2002-2013) from sporadic cases in Switzerland and Germany. The increased isolation frequency continued for 6 months after the detection of Salmonella Szentes in sprouts. No common food exposure could be establish...
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In July 2014, an outbreak of Salmonella enterica ssp. enterica serovar Bovismorbificans was detected in Switzerland. The goal of the outbreak investigation was to rapidly identify and eliminate the contamination source in order to prevent... more
In July 2014, an outbreak of Salmonella enterica ssp. enterica serovar Bovismorbificans was detected in Switzerland. The goal of the outbreak investigation was to rapidly identify and eliminate the contamination source in order to prevent new cases. A case-case study design was applied comprising reported cases of S. Bovismorbificans and cases of other serovars. A trawling questionnaire was administered by telephone interview. Data were collected for 34 cases (20 S. Bovismorbificans and 14 Salmonella spp.) pertaining to food consumption during the 72 hours prior to symptom onset. A statistically significant association between an S. Bovismorbificans infection and the consumption of 'salads' (odds ratio [OR] 14.3, 95% confidence interval [CI] 1.47-138.27) as well as the consumption of 'sprouts' (OR 10.6, 95% CI 1.16-97.59) was found. Principal places of consumption of 'salads' and 'sprouts' in outbreak cases were restaurants in southern Germany (80.0%,...
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Leitfaden zur Validierung mikro- biologischer Prüfverfahren und zur Abschätzung der Messunsicherheit im Bereich Lebensmittel- und Umweltmikrobiologie Lignes directrices pour la validation de méthodes d'essais microbiologiques et l'évaluation de leur incertitude de mesure dans les domaines de la m...more
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Rapid and reliable identification of strains of the genus Cronobacter and its differentiation from phenotypically similar, apathogenic Enterobacter turicensis, Enterobacter helveticus and Enterobacter pulveris is important for... more
Rapid and reliable identification of strains of the genus Cronobacter and its differentiation from phenotypically similar, apathogenic Enterobacter turicensis, Enterobacter helveticus and Enterobacter pulveris is important for surveillance, prevention and control of this food-borne pathogen. Moreover, for Cronobacter a species differentiation is relevant for epidemiological studies. This review summarizes methods for detection, identification and typing of Cronobacter spp.