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Gędas A, Schmidt H, Weiss A. Identification and evaluation of Escherichia coli strain ATCC 8739 as a surrogate for thermal inactivation of enterohemorrhagic Escherichia coli in fruit nectars: Impact of applied techniques on the decimal reduction time. Food Microbiol 2024; 122:104544. [PMID: 38839230 DOI: 10.1016/j.fm.2024.104544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 04/12/2024] [Accepted: 04/13/2024] [Indexed: 06/07/2024]
Abstract
The objective of this study was to identify a suitable surrogate for E. coli O157:H7 strain 19685/91 and O113:H21 strain TS18/08, by assessing their thermal resistance at temperatures of 60 °C, 65 °C, and 72 °C in strawberry nectar. The influence of the matrix and the research methodology on the decimal reduction time (D-value) was investigated. Thermal kinetics and safety assessment demonstrated that E. coli ATCC 8739 is a suitable surrogate. The study demonstrated that the presence of fruit particles in the nectar increased thermal resistance of the tested strains. Variations in D-values were observed depending on the research method employed, with D-values in glass capillaries were up to 6.6 times lower compared to larger sample volumes. Encapsulation of E. coli ATCC 8739 exhibited high efficiency of 90.25 ± 0.26% and maintained stable viable counts after 26 days of storage in strawberry nectar at 4 °C. There were no significant differences in thermal resistance between surrogates directly inoculated into strawberry nectar and those encapsulated in alginate beads. Additionally, the encapsulated strains did not migrate outside the beads. Therefore, encapsulated E. coli ATCC 8739 in alginate beads can be effectively utilized in industrial settings to validate thermal treatments as a reliable and safe method.
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Affiliation(s)
- Astrid Gędas
- Food Microbiology, Hamburg School of Food Science, University of Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany; Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 28, 70599, Stuttgart, Germany
| | - Herbert Schmidt
- Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 28, 70599, Stuttgart, Germany
| | - Agnes Weiss
- Food Microbiology, Hamburg School of Food Science, University of Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany.
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Guidone GHM, Cardozo JG, Silva LC, Sanches MS, Galhardi LCF, Kobayashi RKT, Vespero EC, Rocha SPD. Epidemiology and characterization of Providencia stuartii isolated from hospitalized patients in southern Brazil: a possible emerging pathogen. Access Microbiol 2023; 5:000652.v4. [PMID: 37970084 PMCID: PMC10634494 DOI: 10.1099/acmi.0.000652.v4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 10/08/2023] [Indexed: 11/17/2023] Open
Abstract
This study aimed to characterize the virulence factors and antimicrobial resistance of Providencia stuartii , an opportunistic pathogen that causes human infections. We examined 45 isolates of P. stuartii both genotypically and phenotypically by studying their adherence to HeLa cells, biofilm formation, cytotoxicity and antimicrobial resistance, and analysed their genomes for putative virulence and resistance genes. This study found that most isolates possessed multiple virulence genes, including fimA, mrkA, fptA, iutA, ireA and hlyA, and were cytotoxic to Vero cells. All the isolates were resistant to amoxicillin plus clavulanic acid, levofloxacin and sulfamethoxazole plus trimethoprim, and most were resistant to ceftriaxone and cefepime. All isolates harboured extended-spectrum beta-lactamase coding genes such as bla CTX-M-2 and 23/45(51.11 %) of them also harboured bla CTX-M-9. The gene KPC-2 (carbapenemase) was detected in 8/45(17.77 %) isolates. This study also found clonality among the isolates, indicating the possible spread of the pathogen among patients at the hospital. These results have significant clinical and epidemiological implications and emphasize the importance of a continued understanding of the virulence and antimicrobial resistance of this pathogen for the prevention and treatment of future infections.
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Affiliation(s)
| | - Jennifer Germiniani Cardozo
- Laboratory of Basic and Applied Bacteriology, Department of Microbiology, Center of Biological Sciences, State University of Londrina, Londrina, Brazil
| | - Luana Carvalho Silva
- Laboratory of Bacteriology, Department of Microbiology, Center of Biological Sciences, State University of Londrina, Londrina, Brazil
| | - Matheus Silva Sanches
- Laboratory of Bacteriology, Department of Microbiology, Center of Biological Sciences, State University of Londrina, Londrina, Brazil
| | - Ligia Carla Faccin Galhardi
- Virology Laboratory, Department of Microbiology, Center of Biological Sciences, State University of Londrina, Londrina, Brazil
| | - Renata Katsuko Takayama Kobayashi
- Laboratory of Basic and Applied Bacteriology, Department of Microbiology, Center of Biological Sciences, State University of Londrina, Londrina, Brazil
| | - Eliana Carolina Vespero
- Department of Pathology, Clinical and Toxicological Analysis, Health Sciences Center, University Hospital of Londrina, State University of Londrina, Paraná, Brazil
| | - Sergio Paulo Dejato Rocha
- Laboratory of Bacteriology, Department of Microbiology, Center of Biological Sciences, State University of Londrina, Londrina, Brazil
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Kompes G, Duvnjak S, Reil I, Hendriksen RS, Sørensen LH, Zdelar-Tuk M, Habrun B, Cvetnić L, Bagarić A, Špičić S. First Report and Characterization of the mcr-1 Positive Multidrug-Resistant Escherichia coli Strain Isolated from Pigs in Croatia. Microorganisms 2023; 11:2442. [PMID: 37894098 PMCID: PMC10609023 DOI: 10.3390/microorganisms11102442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/21/2023] [Accepted: 09/26/2023] [Indexed: 10/29/2023] Open
Abstract
The emergence and rapid spread of the plasmid-mediated colistin-resistant mcr-1 gene introduced a serious threat to public health. In 2021, a multi-drug resistant, mcr-1 positive Escherichia coli EC1945 strain, was isolated from pig caecal content in Croatia. Antimicrobial susceptibility testing and whole genome sequencing were performed. Bioinformatics tools were used to determine the presence of resistance genes, plasmid Inc groups, serotype, sequence type, virulence factors, and plasmid reconstruction. The isolated strain showed phenotypic and genotypic resistance to nine antimicrobial classes. It was resistant to colistin, gentamicin, ampicillin, cefepime, cefotaxime, ceftazidime, sulfamethoxazole, chloramphenicol, nalidixic acid, and ciprofloxacin. Antimicrobial resistance genes included mcr-1, blaTEM-1B, blaCTX-M-1, aac(3)-IId, aph(3')-Ia, aadA5, sul2, catA1, gyrA (S83L, D87N), and parC (A56T, S80I). The mcr-1 gene was located within the conjugative IncX4 plasmid. IncI1, IncFIB, and IncFII plasmids were also detected. The isolate also harbored 14 virulence genes and was classified as ST744 and O101:H10. ST744 is a member of the ST10 group which includes commensal, extraintestinal pathogenic E. coli isolates that play a crucial role as a reservoir of genes. Further efforts are needed to identify mcr-1-carrying E. coli isolates in Croatia, especially in food-producing animals to identify such gene reservoirs.
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Affiliation(s)
- Gordan Kompes
- Department for Bacteriology and Parasitology, Croatian Veterinary Institute, 10000 Zagreb, Croatia; (G.K.); (M.Z.-T.); (B.H.); (L.C.); (A.B.); (S.Š.)
| | - Sanja Duvnjak
- Department for Bacteriology and Parasitology, Croatian Veterinary Institute, 10000 Zagreb, Croatia; (G.K.); (M.Z.-T.); (B.H.); (L.C.); (A.B.); (S.Š.)
| | - Irena Reil
- Department for Bacteriology and Parasitology, Croatian Veterinary Institute, 10000 Zagreb, Croatia; (G.K.); (M.Z.-T.); (B.H.); (L.C.); (A.B.); (S.Š.)
| | - Rene S. Hendriksen
- Research Group for Global Capacity Building, National Food Institute, Technical University of Denmark, Kemitorvet, 2800 Lyngby, Denmark; (R.S.H.); (L.H.S.)
| | - Lauge Holm Sørensen
- Research Group for Global Capacity Building, National Food Institute, Technical University of Denmark, Kemitorvet, 2800 Lyngby, Denmark; (R.S.H.); (L.H.S.)
| | - Maja Zdelar-Tuk
- Department for Bacteriology and Parasitology, Croatian Veterinary Institute, 10000 Zagreb, Croatia; (G.K.); (M.Z.-T.); (B.H.); (L.C.); (A.B.); (S.Š.)
| | - Boris Habrun
- Department for Bacteriology and Parasitology, Croatian Veterinary Institute, 10000 Zagreb, Croatia; (G.K.); (M.Z.-T.); (B.H.); (L.C.); (A.B.); (S.Š.)
| | - Luka Cvetnić
- Department for Bacteriology and Parasitology, Croatian Veterinary Institute, 10000 Zagreb, Croatia; (G.K.); (M.Z.-T.); (B.H.); (L.C.); (A.B.); (S.Š.)
| | - Antonela Bagarić
- Department for Bacteriology and Parasitology, Croatian Veterinary Institute, 10000 Zagreb, Croatia; (G.K.); (M.Z.-T.); (B.H.); (L.C.); (A.B.); (S.Š.)
| | - Silvio Špičić
- Department for Bacteriology and Parasitology, Croatian Veterinary Institute, 10000 Zagreb, Croatia; (G.K.); (M.Z.-T.); (B.H.); (L.C.); (A.B.); (S.Š.)
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Yousefipour M, Rezatofighi SE, Ardakani MR. Detection and characterization of hybrid uropathogenic Escherichia coli strains among E. coli isolates causing community-acquired urinary tract infection. J Med Microbiol 2023; 72. [PMID: 36753429 DOI: 10.1099/jmm.0.001660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Introduction. The main aetiological agent of urinary tract infection (UTI) is Escherichia coli, categorized as uropathogenic E. coli (UPEC). The genome of UPEC shows a high degree of plasticity, which leads to the emergence of 'intermediary strains' with different traits from the parental pathotypes.Gap Statement/Aim. We aimed to assess the frequency and types of the hybrid UPEC among isolates causing UTI and characterize virulence properties of these hybrid isolates molecularly and phenotypically.Methodology. After detection of intestinal pathogenic E. coli (IPEC) virulence markers among 200 UPEC isolates, they were assessed for the presence of 40 virulence genes (VGs) of extraintestinal, uropathogenic and diarrhoeagenic E. coli, phylogenetic group typing, phenotypic traits including biofilm formation, adherence and invasion to HeLa cells, haemolysis activity and antimicrobial resistance.Results. The analysis showed 21 (10.5 %) UPEC isolates carried enteroaggregative E. coli (EAEC) and enteropathogenic E. coli (EPEC) virulence markers. Twenty isolates carried the aggR (EAEC) and one the eae and escV genes (EPEC), which were classified as hybrid strains. The most commonly identified genes were fimH (71.5 %), fyuA (66.7 %), iutA (62 %), chuA (57.1) and traT (47.6 %). Biofilm production, adhesion and invasion were found among 17 (81), 18 (85.7) and 11 (52.4 %) hybrids, respectively. Investigation of the genetic characteristics, phylogenetic group and virulence profile of the detected hybrids revealed that they have genetic diversity and do not belong to a particular clonal lineage.Conclusion. The present study reveals that some UPEC may carry virulence markers of IPEC pathotypes. EAEC and EPEC seem to have a greater tendency to form hybrids and cause UTI. Further studies are needed to elucidate what factors contributed to survival in the urinary tract system and facilitate infection and whether these combinations lead to an increase in pathogenicity or not.
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Affiliation(s)
- Mahta Yousefipour
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
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An Emerging Lineage of Uropathogenic Extended Spectrum β-Lactamase Escherichia coli ST127. Microbiol Spectr 2022; 10:e0251122. [PMID: 36416548 PMCID: PMC9769692 DOI: 10.1128/spectrum.02511-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) is one of the most common causes of urinary tract infections. Here, we report for the first time the whole-genome sequencing (WGS) and analysis of four extended-spectrum β-lactamase (ESBL), UPEC sequence type (ST) 127 isolates that were recovered from patients in five hospitals in Armenia from January to August of 2019. A phylogenetic comparison revealed that our isolates were closely related to each other by their core and accessory genomes, despite having been isolated from different regions and hospitals in Armenia. We identified unique genes in our isolates and in a closely related isolate recovered in France. The unique genes (hemolysin E virulence gene, lactate utilization operon lutABC, and endonuclease restriction modification operon hsdMSR) were identified in three separate genomic regions that were adjacent to prophage genes, including one region containing the TonB-dependent iron siderophore receptor gene ireA, which was only found in 5 other ST127 isolates from the European Nucleotide Archive (ENA). We further identified that these isolates possessed unique virulence and metabolic genes and harbored antibiotic resistance genes, including the ESBL genes blaCTX-M-3 (n = 3), blaCTX-M-236 (n = 1), and blaTEM-1 (n = 1), in addition to a quinolone resistance protein gene qnrD1 (n = 1), which was absent in the ST127 isolates obtained from the ENA. Moreover, a plasmid replicon gene IncI2 (n = 1) was unique to ARM88 of the Armenian isolates. Our findings demonstrate that at the time of this study, E. coli ST127 was a cause of urinary tract infections in patients in different regions of Armenia, with a possibility of cross-country transmission between Armenia and France. IMPORTANCE Whole-genome sequencing studies of pathogens causing infectious diseases are seriously lacking in Armenia, hampering global efforts to track, trace and contain infectious disease outbreaks. In this study, we report for the first-time the whole-genome sequencing and analysis of ESBL UPEC ST127 isolates recovered from hospitalized patients in Armenia and compare them with other E. coli ST127 retrieved from the ENA. We found close genetic similarities of the Armenian isolates, indicating that E. coli ST127 was potentially a dominant lineage causing urinary tract infections in Armenia. Furthermore, we identified unique genes that were horizontally acquired in the clusters of Armenian and French isolates that were absent in other ST127 isolates obtained from the ENA. Our findings highlight a possible cross-country transmission between Armenia and France and the idea that the implementation of WGS surveillance could contribute to global efforts in tackling antibiotic resistance, as bacteria carrying antimicrobial resistance (AMR) genes do not recognize borders.
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Nunes PHS, Valiatti TB, Santos ACDM, Nascimento JADS, Santos-Neto JF, Rocchetti TT, Yu MCZ, Hofling-Lima AL, Gomes TAT. Evaluation of the Pathogenic Potential of Escherichia coli Strains Isolated from Eye Infections. Microorganisms 2022; 10:microorganisms10061084. [PMID: 35744602 PMCID: PMC9229993 DOI: 10.3390/microorganisms10061084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/13/2022] [Accepted: 05/21/2022] [Indexed: 11/29/2022] Open
Abstract
While primarily Gram-positive bacteria cause bacterial eye infections, several Gram-negative species also pose eye health risks. Currently, few studies have tried to understand the pathogenic mechanisms involved in E. coli eye infections. Therefore, this study aimed to establish the pathogenic potential of E. coli strains isolated from eye infections. Twenty-two strains isolated between 2005 and 2019 from patients with keratitis or conjunctivitis were included and submitted to traditional polymerase chain reactions (PCR) to define their virulence profile, phylogeny, clonal relationship, and sequence type (ST). Phenotypic assays were employed to determine hemolytic activity, antimicrobial susceptibility, and adhesion to human primary corneal epithelial cells (PCS-700-010). The phylogenetic results indicated that groups B2 and ST131 were the most frequent. Twenty-five virulence genes were found among our strains, with ecp, sitA, fimA, and fyuA being the most prevalent. Two strains presented a hemolytic phenotype, and resistance to ciprofloxacin and ertapenem was found in six strains and one strain, respectively. Regarding adherence, all but one strains adhered in vitro to corneal cells. Our results indicate significant genetic and virulence variation among ocular strains and point to an ocular pathogenic potential related to multiple virulence mechanisms.
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Affiliation(s)
- Pedro Henrique Soares Nunes
- Laboratório Experimental de Patogenicidade de Enterobactérias (LEPE), Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia (DMIP), Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (P.H.S.N.); (T.B.V.); (A.C.d.M.S.); (J.A.d.S.N.); (J.F.S.-N.)
- Laboratório de Oftalmologia (LOFT), Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (T.T.R.); (M.C.Z.Y.); (A.L.H.-L.)
| | - Tiago Barcelos Valiatti
- Laboratório Experimental de Patogenicidade de Enterobactérias (LEPE), Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia (DMIP), Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (P.H.S.N.); (T.B.V.); (A.C.d.M.S.); (J.A.d.S.N.); (J.F.S.-N.)
- Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04039-032, Brazil
| | - Ana Carolina de Mello Santos
- Laboratório Experimental de Patogenicidade de Enterobactérias (LEPE), Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia (DMIP), Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (P.H.S.N.); (T.B.V.); (A.C.d.M.S.); (J.A.d.S.N.); (J.F.S.-N.)
| | - Júllia Assis da Silva Nascimento
- Laboratório Experimental de Patogenicidade de Enterobactérias (LEPE), Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia (DMIP), Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (P.H.S.N.); (T.B.V.); (A.C.d.M.S.); (J.A.d.S.N.); (J.F.S.-N.)
| | - José Francisco Santos-Neto
- Laboratório Experimental de Patogenicidade de Enterobactérias (LEPE), Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia (DMIP), Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (P.H.S.N.); (T.B.V.); (A.C.d.M.S.); (J.A.d.S.N.); (J.F.S.-N.)
| | - Talita Trevizani Rocchetti
- Laboratório de Oftalmologia (LOFT), Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (T.T.R.); (M.C.Z.Y.); (A.L.H.-L.)
| | - Maria Cecilia Zorat Yu
- Laboratório de Oftalmologia (LOFT), Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (T.T.R.); (M.C.Z.Y.); (A.L.H.-L.)
| | - Ana Luisa Hofling-Lima
- Laboratório de Oftalmologia (LOFT), Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (T.T.R.); (M.C.Z.Y.); (A.L.H.-L.)
| | - Tânia Aparecida Tardelli Gomes
- Laboratório Experimental de Patogenicidade de Enterobactérias (LEPE), Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia (DMIP), Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo 04023-062, Brazil; (P.H.S.N.); (T.B.V.); (A.C.d.M.S.); (J.A.d.S.N.); (J.F.S.-N.)
- Correspondence: ; Tel.: +55-11-5576-4848
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Comparative Pathogenomics of Escherichia coli: Polyvalent Vaccine Target Identification through Virulome Analysis. Infect Immun 2021; 89:e0011521. [PMID: 33941580 PMCID: PMC8281228 DOI: 10.1128/iai.00115-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Comparative genomics of bacterial pathogens has been useful for revealing potential virulence factors. Escherichia coli is a significant cause of human morbidity and mortality worldwide but can also exist as a commensal in the human gastrointestinal tract. With many sequenced genomes, it has served as a model organism for comparative genomic studies to understand the link between genetic content and potential for virulence. To date, however, no comprehensive analysis of its complete “virulome” has been performed for the purpose of identifying universal or pathotype-specific targets for vaccine development. Here, we describe the construction of a pathotype database of 107 well-characterized completely sequenced pathogenic and nonpathogenic E. coli strains, which we annotated for major virulence factors (VFs). The data are cross referenced for patterns against pathotype, phylogroup, and sequence type, and the results were verified against all 1,348 complete E. coli chromosomes in the NCBI RefSeq database. Our results demonstrate that phylogroup drives many of the “pathotype-associated” VFs, and ExPEC-associated VFs are found predominantly within the B2/D/F/G phylogenetic clade, suggesting that these phylogroups are better adapted to infect human hosts. Finally, we used this information to propose polyvalent vaccine targets with specificity toward extraintestinal strains, targeting key invasive strategies, including immune evasion (group 2 capsule), iron acquisition (FyuA, IutA, and Sit), adherence (SinH, Afa, Pap, Sfa, and Iha), and toxins (Usp, Sat, Vat, Cdt, Cnf1, and HlyA). While many of these targets have been proposed before, this work is the first to examine their pathotype and phylogroup distribution and how they may be targeted together to prevent disease.
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Abstract
Uropathogenic E. coli (UPEC) is the major cause of urinary tract infections and a frequent cause of sepsis. Nearly half of all UPEC strains produce the potent cytotoxin hemolysin, and its expression is associated with enhanced virulence. In this study, we explored hemolysin variation within the globally dominant UPEC ST131 clone, finding that strains from the ST131 sublineage with the greatest multidrug resistance also possess the strongest hemolytic activity. We also employed an innovative forward genetic screen to define the set of genes required for hemolysin production. Using this approach, and subsequent targeted mutagenesis and complementation, we identified new hemolysin-controlling elements involved in LPS inner core biosynthesis and cytoplasmic chaperone activity, and we show that mechanistically they are required for hemolysin secretion. These original discoveries substantially enhance our understanding of hemolysin regulation, secretion and function. Uropathogenic Escherichia coli (UPEC) is the major cause of urinary tract infections. Nearly half of all UPEC strains secrete hemolysin, a cytotoxic pore-forming toxin. Here, we show that the prevalence of the hemolysin toxin gene (hlyA) is highly variable among the most common 83 E. coli sequence types (STs) represented on the EnteroBase genome database. To explore this diversity in the context of a defined monophyletic lineage, we contextualized sequence variation of the hlyCABD operon within the genealogy of the globally disseminated multidrug-resistant ST131 clone. We show that sequence changes in hlyCABD and its newly defined 1.616-kb-long leader sequence correspond to phylogenetic designation, and that ST131 strains with the strongest hemolytic activity belong to the most extensive multidrug-resistant sublineage (clade C2). To define the set of genes involved in hemolysin production, the clade C2 strain S65EC was completely sequenced and subjected to a genome-wide screen by combining saturated transposon mutagenesis and transposon-directed insertion site sequencing with the capacity to lyse red blood cells. Using this approach, and subsequent targeted mutagenesis and complementation, 13 genes were confirmed to be specifically required for production of active hemolysin. New hemolysin-controlling elements included discrete sets of genes involved in lipopolysaccharide (LPS) inner core biosynthesis (waaC, waaF, waaG, and rfaE) and cytoplasmic chaperone activity (dnaK and dnaJ), and we show these are required for hemolysin secretion. Overall, this work provides a unique description of hemolysin sequence diversity in a single clonal lineage and describes a complex multilevel system of regulatory control for this important toxin.
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Kakian F, Shahini Shams Abadi M, Gholipour A, Fadaie M, Zamanzad B, Khairi S, Parchami S, Damavandi MS. Evaluating the prevalence of virulence genes of Escherichia coli in patients affected by urinary tract infection. GENE REPORTS 2019. [DOI: 10.1016/j.genrep.2019.100433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Valadbeigi H, Esmaeeli E, Ghafourian S, Maleki A, Sadeghifard N. Molecular Analysis of Uropathogenic E.coli Isolates from Urinary Tract Infections. Infect Disord Drug Targets 2018; 19:322-326. [PMID: 30421685 DOI: 10.2174/1871526518666181113091322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 09/25/2018] [Accepted: 11/08/2018] [Indexed: 11/22/2022]
Abstract
INTRODUCTION The aim of the current study was to investigate the prevalence of virulence genes in uropathogenic Escherichia coli (UPEC) isolates in Ilam. MATERIALS AND METHODS For this purpose, a total of 80 UPEC isolates were collected for patients with UTIs during a 6 months period. The multiplex polymerase chain reaction (multiplex PCR) was used to detect the papEF, fimH, iucD, hlyA, fyuA, and ompT genes. RESULTS The prevalence of fimH, papEF, iucD, fyuA, hlyA, hlyA, and ompT genes were 87.5%, 47.5%, 60%, 67.5%, 27.5%, 47.5% and 71.2%, respectively. Among all of the isolates, 27 profiles were obtained. CONCLUSION Our findings demonstrated that the most prevalence was found for fimH, and different distribution of virulence genes suggested different ability of pathogenicity.
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Affiliation(s)
- Hassan Valadbeigi
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Elham Esmaeeli
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Sobhan Ghafourian
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Abbas Maleki
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Nourkhoda Sadeghifard
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
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Genome sequence of lung pathogenic Escherichia coli O78, a chimeric strain isolated from pneumonia forest musk deer. Genes Genomics 2017. [DOI: 10.1007/s13258-017-0545-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Extended-spectrum β-lactamase, shigatoxin and haemolysis capacity of O157 and non-O157 E. coli serotypes from producer-distributor bulk milk. Int Dairy J 2017. [DOI: 10.1016/j.idairyj.2016.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Ntuli V, Njage P, Buys E. Characterization of Escherichia coli and other Enterobacteriaceae in producer-distributor bulk milk. J Dairy Sci 2016; 99:9534-9549. [DOI: 10.3168/jds.2016-11403] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/18/2016] [Indexed: 11/19/2022]
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14
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Pillay L, Olaniran AO. Assessment of physicochemical parameters and prevalence of virulent and multiple-antibiotic-resistant Escherichia coli in treated effluent of two wastewater treatment plants and receiving aquatic milieu in Durban, South Africa. ENVIRONMENTAL MONITORING AND ASSESSMENT 2016; 188:260. [PMID: 27037695 DOI: 10.1007/s10661-016-5232-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 03/14/2016] [Indexed: 06/05/2023]
Abstract
The poor operational status of some wastewater treatment plants often result in the discharge of inadequately treated effluent into receiving surface waters. This is of significant public health concern as there are many informal settlement dwellers (ISDs) that rely on these surface waters for their domestic use. This study investigated the treatment efficiency of two independent wastewater treatment plants (WWTPs) in Durban, South Africa and determined the impact of treated effluent discharge on the physicochemical and microbial quality of the receiving water bodies over a 6-month period. Presumptive Escherichia coli isolates were identified using biochemical tests and detection of the mdh gene via PCR. Six major virulence genes namely eae, hly, fliC, stx1, stx2, and rfbE were also detected via PCR while antibiotic resistance profiles of the isolates were determined using Kirby-Bauer disc diffusion assay. The physicochemical parameters of the wastewater samples ranged variously between 9 and 313.33 mg/L, 1.52 and 76.43 NTUs, and 6.30 and 7.87 for COD, turbidity, and pH respectively, while the E. coli counts ranged between 0 and 31.2 × 10(3) CFU/ml. Of the 200 selected E. coli isolates, the hly gene was found in 28 %, fliC in 20 %, stx2 in 17 %, eae in 14 %, with stx1 and rfbE in only 4 % of the isolates. Notable resistance was observed toward trimethoprim (97 %), tetracycline (56 %), and ampicillin (52.5 %). These results further highlight the poor operational status of these WWTPs and outline the need for improved water quality monitoring and enforcement of stringent guidelines.
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Affiliation(s)
- Leanne Pillay
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban, 4000, Republic of South Africa
| | - Ademola O Olaniran
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban, 4000, Republic of South Africa.
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15
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Kwak MJ, Kim MS, Kwon SK, Cho SH, Kim JF. Genome sequence of Escherichia coli NCCP15653, a group D strain isolated from a diarrhea patient. Gut Pathog 2016; 8:7. [PMID: 26913081 PMCID: PMC4765171 DOI: 10.1186/s13099-016-0084-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 01/04/2016] [Indexed: 11/22/2022] Open
Abstract
Background Pathogenic strains in Escherichia coli can be divided into several pathotypes according to their virulence features. Among them, uropathogenic E. coli causes most of the urinary tract infections and has a genotype distinct from other virulent strains of E. coli. In this study, we sequenced and analyzed the genome of E. coli NCCP15653 isolated from the feces of a diarrhea patient in 2007 in South Korea. Results A phylogenetic tree based on MLST showed that NCCP15653 belongs to the D group of E. coli and located in the lineage containing strains ST2747, UMN026 and 042. In the genome of NCCP15653, genes encoding major virulence factors of uropathogenic E. coli were detected. They include type I fimbriae, hemin uptake proteins, iron/manganese transport proteins, yersiniabactin siderophore proteins, type VI secretion proteins, and hemolysin. On the other hand, genes encoding AslA, OmpA, and the K1 capsule, which are virulence factors associated with invasion of neonatal meningitis-causing E. coli, were also present, while a gene encoding CNF-1 protein, which is a cytotoxic necrotizing factor 1, was not detected. Conclusions Through the genome analysis of NCCP15653, we report an example of a genome of chimeric pathogenic properties. The gene content of NCCP15653, a group D strain, demonstrates that it could be both uropathogenic E. coli and neonatal meningitis-causing E. coli. Our results suggest the dynamic nature of plastic genomes in pathogenic strains of E. coli.
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Affiliation(s)
- Min-Jung Kwak
- Department of Systems Biology and Division of Life Sciences, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749 Republic of Korea
| | - Myung-Soo Kim
- Department of Systems Biology and Division of Life Sciences, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749 Republic of Korea
| | - Soon-Kyeong Kwon
- Department of Systems Biology and Division of Life Sciences, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749 Republic of Korea
| | - Seung-Hak Cho
- Division of Enteric Diseases, Center for Infectious Diseases, Korea National Institute of Health, Heungdeok-Gu, Cheongju, 363-951 Republic of Korea
| | - Jihyun F Kim
- Department of Systems Biology and Division of Life Sciences, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749 Republic of Korea
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16
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Enow COA, Oscarsson J, Zlatkov N, Westermark M, Duperthuy M, Wai SN, Uhlin BE. Elevated recombinant clyA gene expression in the uropathogenic Escherichia coli strain 536, a clue to explain pathoadaptive mutations in a subset of extraintestinal E. coli strains. BMC Microbiol 2014; 14:216. [PMID: 25178918 PMCID: PMC4164713 DOI: 10.1186/s12866-014-0216-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 08/11/2014] [Indexed: 12/25/2022] Open
Abstract
Background Analysis of the Escherichia coli collection of reference strains (ECOR) for the presence of the gene locus clyA, which encodes the pore-forming protein ClyA (cytolysin A), revealed that a non-functional clyA locus is common among certain extraintestinal pathogenic E. coli (ExPEC). In fact, all 15 ECOR group B2 strains and several additionally examined extraintestinal pathogenic (uropathogenic (UPEC) and neonatal meningitis (NBM)) E. coli strains contained various ΔclyA alleles. Results There are at least four different variants of ΔclyA, suggesting that such deletions in clyA have arisen at more than one occasion. On the basis of this occurrence of the truncated clyA genes, we considered that there may be a patho-adaptive selection for deletions in clyA in extraintestinal pathogenic E. coli. In E. coli K-12 the clyA gene has been viewed as “cryptic” since it is tightly silenced by the nucleoid structuring protein H-NS. We constructed a restored clyA+ locus in derivatives of the UPEC strain 536 for further investigation of this hypothesis and, in particular, how the gene would be expressed. Our results show that the level of clyA+ expression is highly increased in the UPEC derivatives in comparison with the non-pathogenic E. coli K-12. Transcription of the clyA+ gene was induced to even higher levels when the SfaX regulatory protein was overproduced. The derivative with a restored clyA+ locus displayed a somewhat slower growth than the parental UPEC strain 536 when a sub-inhibitory concentration of the antimicrobial peptide Polymyxin B was added to the growth medium. Conclusions Taken together, our findings show that the clyA+ locus is expressed at an elevated level in the UPEC strain and we conclude that this is at least in part due to the effect of the SfaX/PapX transcriptional regulators. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0216-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | - Bernt Eric Uhlin
- Department of Molecular Biology, the Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, S-90187, Sweden.
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17
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Gao D, Cheng J, Zheng E, Li Y, Shao Z, Xu Z, Lu C. Eha, a transcriptional regulator of hemolytic activity ofEdwardsiella tarda. FEMS Microbiol Lett 2014; 353:132-40. [DOI: 10.1111/1574-6968.12420] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/02/2014] [Accepted: 03/07/2014] [Indexed: 11/29/2022] Open
Affiliation(s)
- Daqing Gao
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Jing Cheng
- JiangSu University School of Medicine; Zhenjiang China
| | - Enjin Zheng
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Yuhong Li
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Zeye Shao
- Department of Clinical Lab; Southeast University School of Medicine; Nanjing China
| | - Zeyan Xu
- JiangSu University School of Medicine; Zhenjiang China
| | - Chengping Lu
- NanJing Agricultural University, College of Veterinary Medicine; Nanjing China
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18
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Amézquita-López BA, Quiñones B, Lee BG, Chaidez C. Virulence profiling of Shiga toxin-producing Escherichia coli recovered from domestic farm animals in Northwestern Mexico. Front Cell Infect Microbiol 2014; 4:7. [PMID: 24551599 PMCID: PMC3908320 DOI: 10.3389/fcimb.2014.00007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 01/13/2014] [Indexed: 01/13/2023] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a zoonotic enteric pathogen that causes human gastrointestinal illnesses. The present study characterized the virulence profiles of O157 and non-O157 STEC strains, recovered from domestic animals in small rural farms within the agricultural Culiacan Valley in Mexico. Virulence genes coding for adhesins, cytotoxins, proteases, subtypes of Shiga toxin (Stx), and other effectors were identified in the STEC strains by PCR. The genotyping analysis revealed the presence of the effectors nleA, nleB, nleE, and nleH1-2, espK, and espN in the O157:H7 and O111:H8 STEC strains. Furthermore, the genes encoding the autoagglutinating adhesin (Saa) and subtilase (SubA) were exclusively identified in the O8:H19 eae-negative strains. The adhesin (iha) and the silent hemolysin (sheA) genes were detected in 79% of the O157 and non-O157 strains. To examine the relative toxicities of the STEC strains, a fluorescent Vero cell line, Vero-d2EGFPs, was employed to measure the inhibition of protein synthesis by Stx. Analysis of culture supernatants from serotype O8:H19 strains with the stx gene profile stx1a, stx2a, and stx2c and serotypes O75:H8 and O146:H8 strains with the stx gene profile stx1a, stx1c, and stx2b, resulted in a significant reduction in the Vero-d2EGFP fluorescent signal. These observations suggest that these non-O157 strains may have an enhanced ability to inhibit protein synthesis in Vero cells. Interestingly, analysis of the stx2c-positive O157:H7 strains resulted in a high fluorescent signal, indicating a reduced toxicity in the Vero-d2EGFP cells. These findings indicate that the O157 and non-O157 STEC strains, recovered in the Culiacan Valley, display distinct virulence profiles and relative toxicities in mammalian cells and have provided information for evaluating risks associated with zoonotic STEC in this agricultural region in Mexico.
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Affiliation(s)
| | - Beatriz Quiñones
- Produce Safety and Microbiology Research Unit, U.S. Department of Agriculture/Agricultural Research Service, Western Regional Research Center Albany, CA, USA
| | - Bertram G Lee
- Produce Safety and Microbiology Research Unit, U.S. Department of Agriculture/Agricultural Research Service, Western Regional Research Center Albany, CA, USA
| | - Cristóbal Chaidez
- Centro de Investigación en Alimentación y Desarrollo Culiacán, Mexico
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19
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Lorenz SC, Son I, Maounounen-Laasri A, Lin A, Fischer M, Kase JA. Prevalence of hemolysin genes and comparison of ehxA subtype patterns in Shiga toxin-producing Escherichia coli (STEC) and non-STEC strains from clinical, food, and animal sources. Appl Environ Microbiol 2013; 79:6301-11. [PMID: 23934487 PMCID: PMC3811216 DOI: 10.1128/aem.02200-13] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 07/30/2013] [Indexed: 11/20/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) belonging to certain serogroups (e.g., O157 and O26) can cause serious conditions like hemolytic-uremic syndrome (HUS), but other strains might be equally pathogenic. While virulence factors, like stx and eae, have been well studied, little is known about the prevalence of the E. coli hemolysin genes (hlyA, ehxA, e-hlyA, and sheA) in association with these factors. Hemolysins are potential virulence factors, and ehxA and hlyA have been associated with human illness, but the significance of sheA is unknown. Hence, 435 E. coli strains belonging to 62 different O serogroups were characterized to investigate gene presence and phenotypic expression of hemolysis. We further investigated ehxA subtype patterns in E. coli isolates from clinical, animal, and food sources. While sheA and ehxA were widely distributed, e-hlyA and hlyA were rarely found. Most strains (86.7%) were hemolytic, and significantly more hemolytic (95%) than nonhemolytic strains (49%) carried stx and/or eae (P < 0.0001). ehxA subtyping, as performed by using PCR in combination with restriction fragment length polymorphism analysis, resulted in six closely related subtypes (>94.2%), with subtypes A/D being eae-negative STECs and subtypes B, C, E, and F eae positive. Unexpectedly, ehxA subtype patterns differed significantly between isolates collected from different sources (P < 0.0001), suggesting that simple linear models of exposure and transmission need modification; animal isolates carried mostly subtypes A/C (39.3%/42.9%), food isolates carried mainly subtype A (81.9%), and clinical isolates carried mainly subtype C (66.4%). Certain O serogroups correlated with particular ehxA subtypes: subtype A with O104, O113, and O8; B exclusively with O157; C with O26, O111, and O121.
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Affiliation(s)
- Sandra C. Lorenz
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Division of Microbiology, College Park, Maryland, USA
- University of Hamburg, Hamburg School of Food Science, Institute of Food Chemistry, Hamburg, Germany
| | - Insook Son
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Division of Microbiology, College Park, Maryland, USA
| | - Anna Maounounen-Laasri
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Division of Microbiology, College Park, Maryland, USA
| | - Andrew Lin
- U.S. Food and Drug Administration, San Francisco District Laboratory, Alameda, California, USA
| | - Markus Fischer
- University of Hamburg, Hamburg School of Food Science, Institute of Food Chemistry, Hamburg, Germany
| | - Julie A. Kase
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Division of Microbiology, College Park, Maryland, USA
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20
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Molecular and phenotypic characterization of Escherichia coli O26:H8 among diarrheagenic E. coli O26 strains isolated in Brazil. Appl Environ Microbiol 2013; 79:6847-54. [PMID: 23974139 DOI: 10.1128/aem.01693-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli strains of serogroup O26 comprise two distinct groups of pathogens, characterized as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC). Among the several genes related to type III secretion system-secreted effector proteins, espK was found to be highly specific for EHEC O26:H11 and its stx-negative derivative strains isolated in European countries. E. coli O26 strains isolated in Brazil from infant diarrhea, foods, and the environment have consistently been shown to lack stx genes and are thus considered atypical EPEC. However, no further information related to their genetic background is known. Therefore, in this study, we aimed to discriminate and characterize these Brazilian O26 stx-negative strains by phenotypic, genetic, and biochemical approaches. Among 44 isolates confirmed to be O26 isolates, most displayed flagellar antigen H11 or H32. Out of the 13 nonmotile isolates, 2 tested positive for fliCH11, and 11 were fliCH8 positive. The identification of genetic markers showed that several O26:H11 and all O26:H8 strains tested positive for espK and could therefore be discriminated as EHEC derivatives. The presence of H8 among EHEC O26 and its stx-negative derivative isolates is described for the first time. The interaction of three isolates with polarized Caco-2 cells and with intestinal biopsy specimen fragments ex vivo confirmed the ability of the O26 strains analyzed to cause attaching-and-effacing (A/E) lesions. The O26:H32 strains, isolated mostly from meat, were considered nonvirulent. Knowledge of the virulence content of stx-negative O26 isolates within the same serotype helped to avoid misclassification of isolates, which certainly has important implications for public health surveillance.
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21
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Los FCO, Randis TM, Aroian RV, Ratner AJ. Role of pore-forming toxins in bacterial infectious diseases. Microbiol Mol Biol Rev 2013; 77:173-207. [PMID: 23699254 PMCID: PMC3668673 DOI: 10.1128/mmbr.00052-12] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pore-forming toxins (PFTs) are the most common bacterial cytotoxic proteins and are required for virulence in a large number of important pathogens, including Streptococcus pneumoniae, group A and B streptococci, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis. PFTs generally disrupt host cell membranes, but they can have additional effects independent of pore formation. Substantial effort has been devoted to understanding the molecular mechanisms underlying the functions of certain model PFTs. Likewise, specific host pathways mediating survival and immune responses in the face of toxin-mediated cellular damage have been delineated. However, less is known about the overall functions of PFTs during infection in vivo. This review focuses on common themes in the area of PFT biology, with an emphasis on studies addressing the roles of PFTs in in vivo and ex vivo models of colonization or infection. Common functions of PFTs include disruption of epithelial barrier function and evasion of host immune responses, which contribute to bacterial growth and spreading. The widespread nature of PFTs make this group of toxins an attractive target for the development of new virulence-targeted therapies that may have broad activity against human pathogens.
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Affiliation(s)
| | - Tara M. Randis
- Department of Pediatrics, Columbia University, New York, New York, USA
| | - Raffi V. Aroian
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, USA
| | - Adam J. Ratner
- Department of Pediatrics, Columbia University, New York, New York, USA
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22
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Márquez-López A, Ruiz Del Castillo B, Cano ME, Rodríguez-Mirones C, Oteo J, Sáez D, Martínez-Martínez L. Production of HlyA and ClyA haemolysins among quinolone-resistant Escherichia coli isolated from clinical samples. SPRINGERPLUS 2013; 2:71. [PMID: 23543875 PMCID: PMC3607716 DOI: 10.1186/2193-1801-2-71] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 02/15/2013] [Indexed: 11/10/2022]
Abstract
Most Escherichia coli resistant to quinolones are not haemolytic. The objective of this study was to determine the phylogroup, clonal relationship, mechanism of quinolone resistance and virulence factors in 70 haemolytic E. coli resistant to nalidixic acid. Sixty-six isolates contained the hlyA gene, belonged to phylogroup B2, and 61 of them presented low-level resistance to fluoroquinolones. Four isolates presented high-level resistance to fluoroquinolones, contained the clyA gene and were included in phylogroup D. One single isolate (phylogroup D, with low level resistance to fluoroquinolones) contained both cytotoxins.
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Affiliation(s)
- Alicia Márquez-López
- Service of Microbiology, University Hospital Marqués de Valdecilla-IFIMAV, Santander, Spain
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23
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Hilbert DW, Paulish-Miller TE, Tan CK, Carey AJ, Ulett GC, Mordechai E, Adelson ME, Gygax SE, Trama JP. Clinical Escherichia coli isolates utilize alpha-hemolysin to inhibit in vitro epithelial cytokine production. Microbes Infect 2012; 14:628-38. [DOI: 10.1016/j.micinf.2012.01.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 01/18/2012] [Accepted: 01/18/2012] [Indexed: 10/14/2022]
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24
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Fuchs TM, Eisenreich W, Heesemann J, Goebel W. Metabolic adaptation of human pathogenic and related nonpathogenic bacteria to extra- and intracellular habitats. FEMS Microbiol Rev 2012; 36:435-62. [DOI: 10.1111/j.1574-6976.2011.00301.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 07/21/2011] [Indexed: 01/02/2023] Open
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25
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Magalhães CA, Rossato SS, Barbosa AS, Santos TOD, Elias WP, Sircili MP, Piazza RMF. The ability of haemolysins expressed by atypical enteropathogenic Escherichia coli to bind to extracellular matrix components. Mem Inst Oswaldo Cruz 2011; 106:146-52. [PMID: 21537672 DOI: 10.1590/s0074-02762011000200005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 12/01/2010] [Indexed: 01/29/2023] Open
Abstract
Typical and atypical enteropathogenic Escherichia coli (EPEC) are considered important bacterial causes of diarrhoea. Considering the repertoire of virulence genes, atypical EPEC (aEPEC) is a heterogeneous group, harbouring genes that are found in other diarrheagenic E. coli pathotypes, such as those encoding haemolysins. Haemolysins are cytolytic toxins that lyse host cells disrupting the function of the plasma membrane. In addition, these cytolysins mediate a connection to vascular tissue and/or blood components, such as plasma and cellular fibronectin. Therefore, we investigated the haemolytic activity of 72 aEPEC isolates and determined the correlation of this phenotype with the presence of genes encoding enterohaemolysins (Ehly) and cytolysin A (ClyA). In addition, the correlation between the expression of haemolysins and the ability of these secreted proteins to adhere to extracellular matrix (ECM) components was also assessed in this study. Our findings demonstrate that a subset of aEPEC presents haemolytic activity due to the expression of Ehlys and/or ClyA and that this activity is closely related to the ability of these isolates to bind to ECM components.
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26
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Conversion of commensal Escherichia coli K-12 to an invasive form via expression of a mutant histone-like protein. mBio 2011; 2:mBio.00182-11. [PMID: 21896677 PMCID: PMC3172693 DOI: 10.1128/mbio.00182-11] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The HUαE38K, V42L mutant of the bacterial histone-like protein HU causes a major change in the transcription profile of the commensal organism Escherichia coli K-12 (Kar S, Edgar R, Adhya S, Proc. Natl. Acad. Sci. U. S. A. 102:16397–16402, 2005). Among the upregulated genes are several related to pathogenic interactions with mammalian cells, as evidenced by the expression of curli fibers, Ivy, and hemolysin E. When E. coli K-12/ HUαE38K, V42L was added to Int-407 cells, there was host cell invasion, phagosomal disruption, and intracellular replication. The invasive trait was also retained in a murine ileal loop model and intestinal explant assays. In addition to invasion, the internalized bacteria caused a novel subversion of host cell apoptosis through modification and regulation of the BH3-only proteins BimEL and Puma. Changes in the transcription profile were attributed to positive supercoiling of DNA leading to the altered availability of relevant promoters. Using the E. coli K-12/HUαE38K, V42L variant as a model, we propose that traditional commensal E. coli can adopt an invasive lifestyle through reprogramming its cellular transcription, without gross genetic changes. Escherichia coli K-12 is well established as a benign laboratory strain and a human intestinal commensal. Recent evidences, however, indicate that the typical noninvasive nature of resident E. coli can be reversed under specific circumstances even in the absence of any major genomic flux. We previously engineered an E. coli strain with a mutant histone-like protein, HU, which exhibited significant changes in nucleoid organization and global transcription. Here we showed that the changes induced by the mutant HU have critical functional consequences: from a strict extracellular existence, the mutant E. coli adopts an almost obligate intracellular lifestyle. The internalized E. coli exhibits many of the prototypical characteristics of traditional intracellular bacteria, like phagosomal escape, intracellular replication, and subversion of host cell apoptosis. We suggest that E. coli K-12 can switch between widely divergent lifestyles in relation to mammalian host cells by reprogramming its cellular transcription program and without gross changes in its genomic content.
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27
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Mutations affecting export and activity of cytolysin A from Escherichia coli. J Bacteriol 2010; 192:4001-11. [PMID: 20511497 DOI: 10.1128/jb.01283-09] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cytolysin A (known as ClyA, HlyE, and SheA) is a cytolytic pore-forming protein toxin found in several Escherichia coli and Salmonella enterica strains. The structure of its water-soluble monomeric form and that of dodecameric ClyA pores is known, but the mechanisms of ClyA export from bacterial cells and of pore assembly are only partially understood. Here we used site-directed mutagenesis to study the importance of different regions of the E. coli ClyA protein for export and activity. The data indicate that ClyA translocation to the periplasm requires several protein segments located closely adjacent to each other in the "tail" domain of the ClyA monomer, namely, the N- and C-terminal regions and the hydrophobic sequence ranging from residues 89 to 101. Deletion of most of the "head" domain of the monomer (residues 181 to 203), on the other hand, did not strongly affect ClyA secretion, suggesting that the tail domain plays a particular role in export. Furthermore, we found that the N-terminal amphipathic helix alphaA1 of ClyA is crucial for the formation and the properties of the transmembrane channel, and hence for hemolytic activity. Several mutations affecting the C-terminal helix alphaG, the "beta-tongue" region in the head domain, or the hydrophobic region in the tail domain of the ClyA monomer strongly impaired the hemolytic activity and reduced the activity toward planar lipid bilayer membranes but did not totally prevent formation of wild-type-like channels in these artificial membranes. The latter regions thus apparently promote membrane interaction without being directly required for pore formation in a lipid bilayer.
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Hunt S, Green J, Artymiuk PJ. Hemolysin E (HlyE, ClyA, SheA) and Related Toxins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 677:116-26. [DOI: 10.1007/978-1-4419-6327-7_10] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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29
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Stenske KA, Bemis DA, Gillespie BE, Oliver SP, Draughon FA, Matteson KJ, Bartges JW. Prevalence of urovirulence genes cnf, hlyD, sfa/foc, and papGIII in fecal Escherichia coli from healthy dogs and their owners. Am J Vet Res 2009; 70:1401-6. [PMID: 19878023 DOI: 10.2460/ajvr.70.11.1401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the prevalence of 4 urovirulence genes in fecal Escherichia coli isolates from healthy dogs and their owners and to determine whether detection of E coli strains with these genes was associated with a history of urinary tract infection (UTI). SAMPLE POPULATION 61 healthy dog-owner pairs and 30 healthy non-dog owners. PROCEDURES A fecal specimen was obtained from each participant, and 3 colonies of E coli were isolated from each specimen. A multiplex PCR assay was used to detect 4 genes encoding virulence factors: cytotoxic necrotizing factor (cnf), hemolysin (hlyD), s-fimbrial and F1C fimbriae adhesin (sfa/foc), and pilus associated with pyelonephritis G allele III (papGIII). Human participants completed a questionnaire to provide general information and any history of UTI for themselves and, when applicable, their dog. RESULTS 26% (16/61) of dogs, 18% (11/61) of owners, and 20% (6/30) of non-dog owners had positive test results for >or= 1 E coli virulence gene. One or more genes were identified in fecal E coli isolates of both dog and owner in 2% (1/61) of households. There was no difference in the detection of any virulence factor between dog-owner pairs. Female owner history of UTI was associated with detection of each virulence factor in E coli strains isolated from their dogs' feces. CONCLUSIONS AND CLINICAL RELEVANCE Dogs and humans harbored fecal E coli strains possessing the genes cnf, hlyD, sfa/foc, and papGIII that encode urovirulence factors. It was rare for both dog and owner to have fecal E coli strains with these virulence genes.
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Affiliation(s)
- Katherine A Stenske
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA
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Silva E, Leitão S, Tenreiro T, Pomba C, Nunes T, Lopes da Costa L, Mateus L. Genomic and phenotypic characterization of Escherichia coli isolates recovered from the uterus of puerperal dairy cows. J Dairy Sci 2009; 92:6000-10. [DOI: 10.3168/jds.2009-2358] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Hong S, Oh KH, Cho SH, Kim JC, Park MS, Lim HS, Lee BK. Asymptomatic healthy slaughterhouse workers in South Korea carrying Shiga toxin-producing Escherichia coli. ACTA ACUST UNITED AC 2009; 56:41-7. [PMID: 19309486 DOI: 10.1111/j.1574-695x.2009.00545.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A total of 1602 stool samples from healthy employees in a slaughter company were screened by PCR for Shiga toxin (Stx)-producing Escherichia coli (STEC). The PCR product of Stx-encoding genes was detected in 90 (5.6%) of 1602 stool samples. Among the 90 stx-positive workers, the Residual Products Handlers and Slaughterers had rates of 8.0% and 6.0%--higher than Inspectors, Grading Testers and Livestock Hygiene Controllers at 3.3%, 2.0% and 3.5%, respectively. Forty-nine (54.4%) were shown to have stx2; 25 (27.7%) carried stx1 and 16 (17.7%) had both stx1 and 2. Distribution of the stx PCR-positive workers by age revealed an increase in STEC infection with age (P<0.05). Phenotypic and genotypic traits of nine STEC strains isolated from eight slaughter plant workers were characterized. A variety of serotypes, five O serogroups (O8, O54, O59, O103 and O153) and two H serogroups (H7 and H32) were found, but none of the strains belonged to the serogroup O157. Eight Vero cell cytotoxicity assay-positive strains were isolated from the workers and these workers were asymptomatic and healthy. The results of the study show that slaughter plant workers are at high risk of STEC infection.
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Affiliation(s)
- Sahyun Hong
- Center for Infectious Diseases, Division of Enteric Bacterial Infections, Korea National Institute of Health, Seoul, Korea
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Ram S, Vajpayee P, Tripathi U, Singh R, Seth P, Shanker R. Determination of antimicrobial resistance and virulence gene signatures in surface water isolates ofEscherichia coli. J Appl Microbiol 2008; 105:1899-908. [DOI: 10.1111/j.1365-2672.2008.03879.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Hunt S, Moir AJG, Tzokov S, Bullough PA, Artymiuk PJ, Green J. The formation and structure of Escherichia coli K-12 haemolysin E pores. Microbiology (Reading) 2008; 154:633-642. [DOI: 10.1099/mic.0.2007/011700-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Stuart Hunt
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Arthur J. G. Moir
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Svetomir Tzokov
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Per A. Bullough
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Peter J. Artymiuk
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Jeffrey Green
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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Lithgow JK, Haider F, Roberts IS, Green J. Alternate SlyA and H-NS nucleoprotein complexes control hlyE expression in Escherichia coli K-12. Mol Microbiol 2007; 66:685-98. [PMID: 17892462 PMCID: PMC2156107 DOI: 10.1111/j.1365-2958.2007.05950.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Haemolysin E is a cytolytic pore-forming toxin found in several Escherichia coli and Salmonella enterica strains. Expression of hlyE is repressed by the global regulator H-NS (histone-like nucleoid structuring protein), but can be activated by the regulator SlyA. Expression of a chromosomal hlyE–lacZ fusion in an E. coli slyA mutant was reduced to 60% of the wild-type level confirming a positive role for SlyA. DNase I footprint analysis revealed the presence of two separate SlyA binding sites, one located upstream, the other downstream of the hlyE transcriptional start site. These sites overlap AT-rich H-NS binding sites. Footprint and gel shift data showed that whereas H-NS prevented binding of RNA polymerase (RNAP) at the hlyE promoter (PhlyE), SlyA allowed binding of RNAP, but inhibited binding of H-NS. Accordingly, in vitro transcription analyses showed that addition of SlyA protein relieved H-NS-mediated repression of hlyE. Based on these observations a model for SlyA/H-NS regulation of hlyE expression is proposed in which the relative concentrations of SlyA and H-NS govern the nature of the nucleoprotein complexes formed at PhlyE. When H-NS is dominant RNAP binding is inhibited and hlyE expression is silenced; when SlyA is dominant H-NS binding is inhibited allowing RNAP access to the promoter facilitating hlyE transcription.
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Affiliation(s)
- James K Lithgow
- Department of Molecular Biology and Biotechnology, The University of SheffieldWestern Bank, Sheffield S10 2TN, UK.
| | - Fouzia Haider
- Department of Molecular Biology and Biotechnology, The University of SheffieldWestern Bank, Sheffield S10 2TN, UK.
| | - Ian S Roberts
- 1.800 Stopford Building, Faculty of Life Sciences, University of ManchesterOxford Road, Manchester M13 9PT, UK.
| | - Jeffrey Green
- Department of Molecular Biology and Biotechnology, The University of SheffieldWestern Bank, Sheffield S10 2TN, UK.
- For correspondence. E-mail ; Tel. (+44) 114 222 4403; Fax (+44) 0114 222 2800
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Müller D, Greune L, Heusipp G, Karch H, Fruth A, Tschäpe H, Schmidt MA. Identification of unconventional intestinal pathogenic Escherichia coli isolates expressing intermediate virulence factor profiles by using a novel single-step multiplex PCR. Appl Environ Microbiol 2007; 73:3380-90. [PMID: 17400780 PMCID: PMC1907121 DOI: 10.1128/aem.02855-06] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Intestinal pathogenic Escherichia coli represents a global health problem for mammals, including humans. At present, diarrheagenic E. coli bacteria are grouped into seven major pathotypes that differ in their virulence factor profiles, severity of clinical manifestations, and prognosis. In this study, we developed and evaluated a one-step multiplex PCR (MPCR) for the straightforward differential identification of intestinal pathotypes of E. coli. The specificity of this novel MPCR was validated by using a subset of reference strains and further confirmed by PCR-independent pheno- and genotypic characterization. Moreover, we tested 246 clinical E. coli isolates derived from diarrhea patients from several distinct geographic regions. Interestingly, besides strains belonging to the defined and well-described pathotypes, we identified five unconventional strains expressing intermediate virulence factor profiles. These strains have been further characterized and appear to represent intermediate strains carrying genes and expressing factors associated with enteropathogenic E. coli, Shiga toxin-producing E. coli, enterotoxigenic E. coli, and enteroaggregative E. coli alike. These strains represent further examples of the extraordinary plasticity of the E. coli genome. Moreover, this implies that the important identification of specific pathotypes has to be based on a broad matrix of indicator genes. In addition, the presence of intermediate strains needs to be accounted for.
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Affiliation(s)
- Daniel Müller
- Institut für Infektiologie, Zentrum für Molekularbiologie der Entzündung (ZMBE), Von-Esmarch-Str. 56, D-48149 Münster, Germany
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Müller CM, Dobrindt U, Nagy G, Emödy L, Uhlin BE, Hacker J. Role of histone-like proteins H-NS and StpA in expression of virulence determinants of uropathogenic Escherichia coli. J Bacteriol 2006; 188:5428-38. [PMID: 16855232 PMCID: PMC1540026 DOI: 10.1128/jb.01956-05] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The histone-like protein H-NS is a global regulator in Escherichia coli that has been intensively studied in nonpathogenic strains. However, no comprehensive study on the role of H-NS and its paralogue, StpA, in gene expression in pathogenic E. coli has been carried out so far. Here, we monitored the global effects of H-NS and StpA in a uropathogenic E. coli isolate by using DNA arrays. Expression profiling revealed that more than 500 genes were affected by an hns mutation, whereas no effect of StpA alone was observed. An hns stpA double mutant showed a distinct gene expression pattern that differed in large part from that of the hns single mutant. This suggests a direct interaction between the two paralogues and the existence of distinct regulons of H-NS and an H-NS/StpA heteromeric complex. hns mutation resulted in increased expression of alpha-hemolysin, fimbriae, and iron uptake systems as well as genes involved in stress adaptation. Furthermore, several other putative virulence genes were found to be part of the H-NS regulon. Although the lack of H-NS, either alone or in combination with StpA, has a huge impact on gene expression in pathogenic E. coli strains, its effect on virulence is ambiguous. At a high infection dose, hns mutants trigger more sudden lethality due to their increased acute toxicity in murine urinary tract infection and sepsis models. At a lower infectious dose, however, mutants lacking H-NS are attenuated through their impaired growth rate, which can only partially be compensated for by the higher expression of numerous virulence factors.
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Affiliation(s)
- Claudia M Müller
- Institut für Molekulare Infektionsbiologie, Röntgenring 11, D-97070 Würzburg, Germany
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Eifler N, Vetsch M, Gregorini M, Ringler P, Chami M, Philippsen A, Fritz A, Müller SA, Glockshuber R, Engel A, Grauschopf U. Cytotoxin ClyA from Escherichia coli assembles to a 13-meric pore independent of its redox-state. EMBO J 2006; 25:2652-61. [PMID: 16688219 PMCID: PMC1478193 DOI: 10.1038/sj.emboj.7601130] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Accepted: 04/13/2006] [Indexed: 11/09/2022] Open
Abstract
ClyA is a pore-forming toxin from virulent Escherichia coli and Salmonella enterica strains. Here, we show that the intrinsic hemolytic activity of ClyA is independent of its redox state, and that the assembly of both reduced and oxidized ClyA to the ring-shaped oligomer is triggered by contact with lipid or detergent. A rate-limiting conformational transition in membrane-bound ClyA monomers precedes their assembly to the functional pore. We obtained a three-dimensional model of the detergent-induced oligomeric complex at 12 A resolution by combining cryo- and negative stain electron microscopy with mass measurements by scanning transmission electron microscopy. The model reveals that 13 ClyA monomers assemble into a cylinder with a hydrophobic cap region, which may be critical for membrane insertion.
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Affiliation(s)
- Nora Eifler
- Maurice E Müller Institute for Microscopy, Biozentrum, University of Basel, Basel, Switzerland
| | - Michael Vetsch
- Institute for Molecular Biology & Biophysics, ETH Zürich, Zürich, Switzerland
| | - Marco Gregorini
- Maurice E Müller Institute for Microscopy, Biozentrum, University of Basel, Basel, Switzerland
| | - Philippe Ringler
- Maurice E Müller Institute for Microscopy, Biozentrum, University of Basel, Basel, Switzerland
| | - Mohamed Chami
- Maurice E Müller Institute for Microscopy, Biozentrum, University of Basel, Basel, Switzerland
| | - Ansgar Philippsen
- Maurice E Müller Institute for Microscopy, Biozentrum, University of Basel, Basel, Switzerland
| | - Andrea Fritz
- Institute for Molecular Biology & Biophysics, ETH Zürich, Zürich, Switzerland
| | - Shirley A Müller
- Maurice E Müller Institute for Microscopy, Biozentrum, University of Basel, Basel, Switzerland
| | - Rudi Glockshuber
- Institute for Molecular Biology & Biophysics, ETH Zürich, Zürich, Switzerland
| | - Andreas Engel
- Maurice E Müller Institute for Microscopy, Biozentrum, University of Basel, Basel, Switzerland
- Maurice E Müller Institute for Microscopy, Bonzentrum, University of Basel, 4056 Basel, Switzerland. Tel.: +41 61 267 22 61; Fax: +41 61 267 21 09; E-mail:
| | - Ulla Grauschopf
- Institute for Molecular Biology & Biophysics, ETH Zürich, Zürich, Switzerland
- Institute for Molecular Biology & Biophysics, ETH Zürich, 8093 Zürich, Switzerland. Tel.: +41 44 633 24 82; Fax: +41 44 633 10 36; E-mail:
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