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1.
Gut ; 73(7): 1052-1075, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38609165

RESUMO

The first British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS)-endorsed faecal microbiota transplant (FMT) guidelines were published in 2018. Over the past 5 years, there has been considerable growth in the evidence base (including publication of outcomes from large national FMT registries), necessitating an updated critical review of the literature and a second edition of the BSG/HIS FMT guidelines. These have been produced in accordance with National Institute for Health and Care Excellence-accredited methodology, thus have particular relevance for UK-based clinicians, but are intended to be of pertinence internationally. This second edition of the guidelines have been divided into recommendations, good practice points and recommendations against certain practices. With respect to FMT for Clostridioides difficile infection (CDI), key focus areas centred around timing of administration, increasing clinical experience of encapsulated FMT preparations and optimising donor screening. The latter topic is of particular relevance given the COVID-19 pandemic, and cases of patient morbidity and mortality resulting from FMT-related pathogen transmission. The guidelines also considered emergent literature on the use of FMT in non-CDI settings (including both gastrointestinal and non-gastrointestinal indications), reviewing relevant randomised controlled trials. Recommendations are provided regarding special areas (including compassionate FMT use), and considerations regarding the evolving landscape of FMT and microbiome therapeutics.


Assuntos
Infecções por Clostridium , Transplante de Microbiota Fecal , Gastroenterologia , Transplante de Microbiota Fecal/métodos , Humanos , Infecções por Clostridium/terapia , Gastroenterologia/normas , COVID-19/terapia , SARS-CoV-2 , Recidiva , Clostridioides difficile , Reino Unido , Sociedades Médicas
2.
J Antimicrob Chemother ; 73(5): 1368-1388, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29514211

RESUMO

Background: ESBL-producing Enterobacteriaceae (ESBLPE) are increasing in prevalence worldwide and are more difficult to treat than non-ESBLPE. Their prevalence in the UK general population is unknown, as the only previous UK ESBLPE faecal colonization study involved patients with diarrhoea. Objectives: To estimate the prevalence of CTX-M ESBLPE faecal colonization in the general adult population of England in 2014, and investigate risk factors. Methods: A stratified random sample of 58 337 registered patients from 16 general practices within four areas of England were invited to participate by returning faeces specimens and self-completed questionnaires. Specimens were tested for ESBLPE and carbapenemase-producing Enterobacteriaceae (CPE). Results: 2430 individuals participated (4% of those invited). The estimated prevalence of colonization with CTX-M ESBLPE in England was 7.3% (95% CI 5.6%-9.4%) (Shropshire 774 participants, 4.9% colonization; Southampton City 740 participants, 9.2%; Newham 612 participants, 12.7%; Heart of Birmingham 234 individuals, 16.0%) and was particularly high in: those born in Afghanistan (10 participants, 60.0% colonization, 95% CI 29.7%-84.2%); those born on the Indian subcontinent (India, Pakistan, Bangladesh or Sri Lanka) (259 participants, 25.0% colonization, 95% CI 18.5%-32.9%); travellers to South Asia (India, Pakistan, Bangladesh, Sri Lanka or Nepal) in the last year (140 participants, 38.5% colonization, 95% CI 27.8%-50.5%); and healthcare domestics (8 participants, unweighted 37.5% colonization, 95% CI 8.5%-75.5%). Risk factors identified included: being born in the Indian subcontinent (aOR 5.4, 95% CI 3.0-9.7); travel to South Asia (aOR 2.9, 95% CI 1.8-4.8) or to Africa, China, South or Central America, South East or Pacific Asia or Afghanistan (aOR 2.6, 95% CI 1.7-4.1) in the last year; and working as a healthcare domestic (aOR 6.2, 95% CI 1.3-31). None of the 48 participants who took co-amoxiclav in the last year was colonized with CTX-M ESBLPE. blaCTX-M-15 accounted for 66% of CTX-M ESBLPE positives. 0.1% (two participants) were colonized with CPE. Conclusions: CTX-M ESBLPE are established in the general population in England and prevalence is particularly high in people from certain countries of birth or with recent travel. We recommend that these findings be taken into account in guidance on the empirical management of patients presenting with a likely Enterobacteriaceae infection.


Assuntos
Infecções por Enterobacteriaceae/epidemiologia , Infecções por Enterobacteriaceae/microbiologia , Enterobacteriaceae/enzimologia , Fezes/microbiologia , beta-Lactamases/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Emigração e Imigração , Inglaterra/epidemiologia , Enterobacteriaceae/isolamento & purificação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores de Risco , Viagem , Adulto Jovem
3.
BMC Infect Dis ; 14: 154, 2014 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-24656142

RESUMO

BACKGROUND: Despite scientific advances in typing of C. difficile strains very little is known about how hospital staff use typing results during periods of increased incidence (PIIs). This qualitative study, undertaken alongside a randomised controlled trial (RCT), explored this issue. The trial compared ribotyping versus more rapid genotyping (MLVA or multilocus variable repeat analysis) and found no significant difference in post 48 hour cases (C difficile transmissions). METHODS: In-depth qualitative interviews with senior staff in 11/16 hospital trusts in the trial (5 MLVA and 6 Ribotyping). Semi-structured interviews were conducted at end of the trial period. Transcripts were content analysed using framework analysis supported by NVivo-8 software. Common sub-themes were extracted by two researchers independently. These were compared and organised into over-arching categories or 'super-ordinate themes'. RESULTS: The trial recorded that 45% of typing tests had some impact on infection control (IC) activities. Interviews indicated that tests had little impact on initial IC decisions. These were driven by hospital protocols and automatically triggered when a PII was identified. To influence decision-making, a laboratory turnaround time < 3 days (ideally 24 hours) was suggested; MLVA turnaround time was 5.3 days. Typing results were predominantly used to modify initiated IC activities such as ward cleaning, audits of practice or staff training; major decisions (e.g. ward closure) were unaffected. Organisational factors could limit utilisation of MLVA results. Results were twice as likely to be reported as 'aiding management' (indirect benefit) than impacting on IC activities (direct effect). Some interviewees considered test results provided reassurance about earlier IC decisions; others identified secondary benefits on organisational culture. An underlying benefit of improved discrimination provided by MLVA typing was the ability to explore epidemiology associated with CDI cases in a hospital more thoroughly. CONCLUSIONS: Ribotyping and MLVA are both valued by users. MLVA had little additional direct impact on initial infection control decisions. This would require reduced turnaround time. The major impact is adjustments to earlier IC measures and retrospective reassurance. For this, turnaround time is less important than discriminatory power. The potential remains for wider use of genotyping to examine transmission routes.


Assuntos
Atitude do Pessoal de Saúde , Clostridioides difficile/classificação , Enterocolite Pseudomembranosa/microbiologia , Técnicas de Genotipagem/métodos , Ensaios Clínicos Controlados Aleatórios como Assunto/métodos , Ensaios Clínicos Controlados Aleatórios como Assunto/psicologia , Ribotipagem/métodos , Clostridioides difficile/genética , Clostridioides difficile/isolamento & purificação , Infecção Hospitalar/diagnóstico , Infecção Hospitalar/microbiologia , Enterocolite Pseudomembranosa/diagnóstico , Humanos , Entrevistas como Assunto , Reação em Cadeia da Polimerase/métodos , Estudos Retrospectivos
4.
J Clin Microbiol ; 51(10): 3308-13, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23903542

RESUMO

Clostridium difficile infection is almost unrecognized in mainland China. We have undertaken a study in a large Chinese teaching hospital in Changsha, Hunan, China, to identify cases of C. difficile, record patient characteristics, and define the molecular epidemiology with respect to ribotype distribution and cross-infection. Between April 2009 and February 2010, we examined fecal samples from 70 hospitalized patients with diarrhea who were receiving or had received antibiotics within the previous 6 weeks. Clinical information was collected and the samples were cultured for C. difficile retrospectively. Isolates were ribotyped, and multiple-locus variable-number tandem-repeat assay (MLVA) subtyping was performed on clusters of the same ribotype. The mean age of patients from whom C. difficile was cultured was 58 years, with only 4/21 patients aged >65 years. All patients, with a single exception, had received a third-generation cephalosporin and/or a quinolone antibiotic. Twenty-one isolates of C. difficile were recovered, and seven different ribotypes were identified, the dominant types being 017 (48%), 046 (14%), and 012 (14%). We identified two clusters of cross-infection with indistinguishable isolates of ribotype 017, with evidence of spread both within and between wards. We have identified C. difficile as a possibly significant problem, with cross-infection and a distinct ribotype distribution, in a large Chinese hospital. C. difficile may be underrecognized in China, and further epidemiological studies across the country together with the introduction of routine diagnostic testing are needed to ascertain the size of this potentially significant problem.


Assuntos
Clostridioides difficile/classificação , Clostridioides difficile/isolamento & purificação , Infecções por Clostridium/epidemiologia , Infecção Hospitalar/epidemiologia , Diarreia/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/uso terapêutico , Ásia , China/epidemiologia , Clostridioides difficile/genética , Infecções por Clostridium/microbiologia , Análise por Conglomerados , Infecção Hospitalar/microbiologia , Diarreia/microbiologia , Fezes/microbiologia , Feminino , Genótipo , Hospitais , Humanos , Masculino , Pessoa de Meia-Idade , Repetições Minissatélites , Epidemiologia Molecular , Ribotipagem
5.
J Clin Microbiol ; 50(10): 3244-8, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22837319

RESUMO

The early identification of outbreaks is crucial for the control of Clostridium difficile infection. This study aimed to determine if the number of hospital-acquired C. difficile infections could be reduced by rapidly typing C. difficile strains using multiple-locus variable-number tandem-repeat analysis (MLVA) compared to typing using PCR ribotyping. A total of 16 hospitals were recruited to the study, and all periods of increased incidence (PIIs) of C. difficile infection were identified. The hospitals were randomized into two study arms, the test and the control, with all isolates typed in the test using MLVA and in the control using PCR ribotyping. Following a PII, each hospital received a structured questionnaire regarding control measures implemented or stopped prior to or following the typing results. During the study period, there were a total of 1,682 hospital-apportioned C. difficile toxin-positive cases, with 868 in the control and 814 in the test, with modeling demonstrating no differences between the two arms. A total of 245 PIIs occurred, involving 785 patients. There was a significant difference in the mean turnaround time between the ribotyping and MLVA typing (13.6 and 5.3 days, respectively [P < 0.001]). The discriminatory ability of MLVA was greater than ribotyping, with 85 outbreaks being confirmed by ribotyping and 62 by MLVA. In the test arm, 40.6% of respondents strongly agreed that the typing result had aided their management of clusters, as opposed to 9.9% in the control. The study demonstrated the utility of rapidly typing C. difficile strains, demonstrating that it aided the management of clusters, enabling effective targeting of infection control resources.


Assuntos
Clostridioides difficile/classificação , Clostridioides difficile/genética , Infecções por Clostridium/epidemiologia , Infecções por Clostridium/microbiologia , Repetições Minissatélites , Tipagem Molecular/métodos , Clostridioides difficile/isolamento & purificação , Análise por Conglomerados , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Humanos , Epidemiologia Molecular/métodos , Ribotipagem/métodos , Fatores de Tempo
6.
F1000Res ; 10: 373, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34367617

RESUMO

Background: Faecal transplantation is an evidence-based treatment for Clostridioides difficile. Patients infected with SARS-CoV-2 have been shown to shed the virus in stool for up to 33 days, well beyond the average clearance time for upper respiratory tract shedding. We carried out an analytical and clinical validation of reverse-transcriptase quantitative (RT-qPCR) as well as LAMP, LamPORE and droplet digital PCR in the detection of SARS-CoV-2 RNA in stool from donated samples for faecal microbiota transplantation (FMT), spiked samples and asymptomatic inpatients in an acute surgical unit.  Methods: Killed SARS-CoV-2 viral lysate and extracted RNA was spiked into donor stool & FMT and a linear dilution series from 10 -1 to 10 -5 and tested via RT-qPCR, LAMP, LamPORE and ddPCR against SARS-CoV-2. Patients admitted to the critical care unit with symptomatic SARS-CoV-2 and sequential asymptomatic patients from acute presentation to an acute surgical unit were also tested. Results: In a linear dilution series, detection of the lowest dilution series was found to be 8 copies per microlitre of sample. Spiked lysate samples down to 10 -2 dilution were detected in FMT samples using RTQPCR, LamPORE and ddPCR and down to 10 -1 with LAMP. In symptomatic patients 5/12 had detectable SARS-CoV-2 in stool via RT-qPCR and 6/12 via LamPORE, and in 1/97 asymptomatic patients via RT-qPCR. Conclusion: RT-qPCR can be detected in FMT donor samples using RT-qPCR, LamPORE and ddPCR to low levels using validated pathways. As previously demonstrated, nearly half of symptomatic and less than one percent of asymptomatic patients had detectable SARS-CoV-2 in stool.


Assuntos
COVID-19 , SARS-CoV-2 , Transplante de Microbiota Fecal , Humanos , RNA Viral/genética , Reação em Cadeia da Polimerase em Tempo Real
7.
J Gastrointestin Liver Dis ; 30(1): 147-163, 2021 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-33723543

RESUMO

Fecal microbiota transplantation involves the infusion of intestinal microorganisms via the transfer of a stool from a healthy individual into a diseased individual, with the intent of restoring normal intestinal flora. Fecal transplant is proposed for the treatment of refractory Clostridioides difficile infection. At present, recurrent Clostridioides difficile infection is the only indication supported by solid scientific evidence. Regulations by healthcare authorities vary among different countries. Considering that Romania does not have an available national guideline to offer standardization, this paper aimed to create a national fecal microbiota transplantation guideline concerning indications, techniques and donor screening, developed by international and local scientific working groups.


Assuntos
Infecções por Clostridium/terapia , Transplante de Microbiota Fecal/métodos , Clostridioides difficile , Transplante de Microbiota Fecal/normas , Fezes/microbiologia , Humanos , Guias de Prática Clínica como Assunto , Romênia
8.
Microb Genom ; 7(3)2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33720817

RESUMO

The Liverpool epidemic strain (LES) is an important transmissible clonal lineage of Pseudomonas aeruginosa that chronically infects the lungs of people with cystic fibrosis (CF). Previous studies have focused on the genomics of the LES in a limited number of isolates, mostly from one CF centre in the UK, and from studies highlighting identification of the LES in Canada. Here we significantly extend the current LES genome database by genome sequencing 91 isolates from multiple CF centres across the UK, and we describe the comparative genomics of this large collection of LES isolates from the UK and Canada. Phylogenetic analysis revealed that the 145 LES genomes analysed formed a distinct clonal lineage when compared with the wider P. aeruginosa population. Notably, the isolates formed two clades: one associated with isolates from Canada, and the other associated with UK isolates. Further analysis of the UK LES isolates revealed clustering by clinic geography. Where isolates clustered closely together, the association was often supported by clinical data linking isolates or patients. When compared with the earliest known isolate, LESB58 (from 1988), many UK LES isolates shared common loss-of-function mutations, such as in genes gltR and fleR. Other loss-of-function mutations identified in previous studies as common adaptations during CF chronic lung infections were also identified in multiple LES isolates. Analysis of the LES accessory genome (including genomic islands and prophages) revealed variations in the carriage of large genomic regions, with some evidence for shared genomic island/prophage complement according to clinic location. Our study reveals divergence and adaptation during the spread of the LES, within the UK and between continents.


Assuntos
Infecções por Pseudomonas/microbiologia , Infecções por Pseudomonas/transmissão , Pseudomonas aeruginosa/isolamento & purificação , Adaptação Fisiológica , Canadá , Fibrose Cística/complicações , Epidemias , Genoma Bacteriano , Humanos , Pulmão/microbiologia , Infecções Oportunistas/microbiologia , Infecções Oportunistas/transmissão , Filogenia , Infecções por Pseudomonas/etiologia , Pseudomonas aeruginosa/classificação , Pseudomonas aeruginosa/fisiologia , Reino Unido/epidemiologia
9.
BMJ Open ; 7(12): e017947, 2017 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-29229656

RESUMO

OBJECTIVES: This study aims to highlight problems with recruiting to an English stool sample community prevalence study. It was part of a larger cross-sectional research to determine the risk factors for the presence of extended-spectrum beta-lactamase and carbapenemase-producing coliforms in stool samples of the asymptomatic general English population. SETTING: Four National Health Service primary care trusts (PCTs) of England representing a different section of the population of England: Newham PCT; Heart of Birmingham Teaching PCT; Shropshire County PCT; and Southampton City PCT. PARTICIPANTS: Sixteen general practices across the four PCTs were purposefully selected. After stratification of GP lists by age, ethnicity and antibiotic use, 58 337 randomly selected patients were sent a postal invitation.Patients who had died, moved to a different surgery, were deemed too ill by their General Practitioner or hospitalised at the time of mailing were excluded. RESULTS: Stool and questionnaire returns varied by area, age, gender and ethnicity; the highest return rate of 27.3% was in Shropshire in the age group of over 60 years; the lowest, 0.6%, was in Birmingham in the age group of 18-39 years. Whereas only 3.9%(2296) returned a completed questionnaire and stool sample, 94.9% of participants gave permission for their sample and data to be used in future research. CONCLUSION: Researchers should consider the low stool specimen return rate and wide variation by ethnicity and age when planning future studies involving stool specimen collection. This is particularly pertinent if the study has no health benefit to participants. Further research is needed to explore how to improve recruitment in multicultural communities and in younger people.


Assuntos
Fezes , Seleção de Pacientes , Kit de Reagentes para Diagnóstico/estatística & dados numéricos , Recusa de Participação/estatística & dados numéricos , Adulto , Estudos Transversais , Inglaterra , Fezes/microbiologia , Feminino , Medicina Geral , Bactérias Gram-Negativas , Inquéritos Epidemiológicos/estatística & dados numéricos , Humanos , Pessoa de Meia-Idade , Serviços Postais/estatística & dados numéricos , Manejo de Espécimes
10.
J Mol Biol ; 349(2): 302-16, 2005 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-15890197

RESUMO

KorB, encoded by plasmid RK2, belongs to the ParB family of active partitioning proteins. It binds to 12 operators on the RK2 genome and was previously known to repress promoters immediately adjacent to operators O(B)1, O(B)10 and O(B)12 (proximal) or up to 154 bp away (distal) from O(B)2, O(B)9 and O(B)11. To achieve strong repression, KorB requires a cooperative interaction with one of two other plasmid-encoded repressors, KorA or TrbA. Reporter gene assays were used in this study to test whether the additional KorB operators may influence transcription and to test how KorB acts at a distance. The distance between O(B)9 and trbBp could be increased to 1.6kb with little reduction in repression or cooperativity with TrbA. KorB was also able to repress the promoter and cooperate with TrbA when the O(B) site was placed downstream of trbBp. This suggested a potential regulatory role for O(B) sites located a long way from any known promoter on RK2. O(B)4, 1.9kb upstream of traGp, was shown to mediate TrbA-potentiated KorB repression of this promoter, but no effect on traJp upstream of O(B)4 was observed, which may be due to the roadblocking or topological influence of the nucleoprotein complex formed at the adjacent transfer origin, oriT. Repression and cooperativity were alleviated significantly when a lac operator was inserted between O(B)9 and trbBp in the context of a LacI+ host, a standard test for spreading of a DNA-binding protein. On the other hand, a standard test for DNA looping, movement of the operator to the opposite face of the DNA helix from the natural binding site, did not significantly affect KorB repression or cooperativity with TrbA and KorA over relatively short distances. While these results are more consistent with spreading as the mechanism by which KorB reaches its target, previous estimates of KorB molecules per cell are not consistent with there being enough to spread up to 1kb from each O(B). A plausible model is therefore that KorB can do both, spreading over relatively short distances and looping over longer distances.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Plasmídeos/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Sítios de Ligação , Proteínas de Escherichia coli/metabolismo , Regiões Operadoras Genéticas/genética , Regiões Promotoras Genéticas/genética , Ligação Proteica
12.
J Infect ; 73(2): 115-22, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27246801

RESUMO

OBJECTIVES: We aim to study the disease burden, risk factors and severity of Clostridium difficile infection (CDI) in Hong Kong. METHODS: We conducted a prospective, case-control study in three acute-care hospitals in Hong Kong. Adult inpatients who developed CDI diarrhoea confirmed by PCR (n = 139) were compared with the non-CDI controls (n = 114). Ribotyping of isolates and antimicrobial susceptibility testing were performed. RESULTS: The estimated crude annual incidence of CDI was 23-33/100,000 population, and 133-207/100,000 population among those aged ≥65 years. The mean age of CDI patients was 71.5. Nursing home care, recent hospitalization, antibiotics exposure (adjusted OR 3.0, 95% CI 1.3-7.1) and proton-pump inhibitors use (adjusted OR 2.2, 95% CI 1.2-3.9) were risk factors. Severe CDI occurred in 41.7%. Overall mortality was 16.5% (among severe CDI, 26.5%). The commonest ribotypes were 002 (22.8%), 014 (14.1%), 012 and 046; ribotype 027 was absent. Ribotype 002 was associated with fluoroquinolone resistance and higher mortality (47.6% vs. 12.7%; adjusted HR 2.8, 95% CI 1.1-7.0). CONCLUSIONS: Our findings show high morbidity and mortality of CDI in the older adults, and identify ribotype 002 as a possible virulent strain causing serious infections in this cohort.


Assuntos
Clostridioides difficile/patogenicidade , Infecções por Clostridium/epidemiologia , Infecções por Clostridium/microbiologia , Infecção Hospitalar/epidemiologia , Ribotipagem , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/uso terapêutico , Estudos de Casos e Controles , Clostridioides difficile/classificação , Clostridioides difficile/genética , Clostridioides difficile/isolamento & purificação , Infecções por Clostridium/imunologia , Infecções por Clostridium/mortalidade , Colite/tratamento farmacológico , Colite/microbiologia , Efeitos Psicossociais da Doença , Infecção Hospitalar/microbiologia , Diarreia/epidemiologia , Diarreia/microbiologia , Feminino , Fluoroquinolonas/uso terapêutico , Hong Kong/epidemiologia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Estudos Prospectivos , Fatores de Risco , Índice de Gravidade de Doença
13.
Plasmid ; 59(3): 163-75, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18374415

RESUMO

The ParB family partitioning protein, KorB, of plasmid RK2 is central to a regulatory network coordinating replication, maintenance and transfer genes. Previous immunofluorescence microscopy indicated that the majority of KorB is localized in plasmid foci. The 12 identified KorB binding sites on RK2 are differentiated by: position relative to promoters; binding strength; and cooperativity with other repressors and so the distribution of KorB may be sequestered around a sub-set of sites. However, chromatin immunoprecipitation analysis showed that while RK2 DNA molecules appear to sequester KorB to create a higher local concentration, cooperativity between DNA binding proteins does not result in major differences in binding site occupancy. Thus under steady state conditions all operators are close to fully occupied and this correlates with gene expression on the plasmid being highly repressed.


Assuntos
Proteínas de Bactérias/química , Regulação Bacteriana da Expressão Gênica , Sítios de Ligação , Imunoprecipitação da Cromatina , DNA/química , DNA/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Inativação Gênica , Genes Reporter , Genoma Bacteriano , Imunoprecipitação , Modelos Genéticos , Plasmídeos/metabolismo , Ligação Proteica , Pseudomonas putida/metabolismo , Simportadores/metabolismo
14.
Mol Microbiol ; 49(4): 1095-108, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12890031

RESUMO

A network of circuits, with KorB and TrbA as key regulators, controls genes for conjugative transfer of broad host range plasmid RK2. To assess the importance of the TrbA regulon, mutational analysis was applied to the TrbA operator at the trbB promoter and then to other TrbA-regulated promoters in the tra region. All identified TrbA operators are submaximal; in the case of trbBp, a G to A transition that made the operator core a perfect palindrome increased repression by about 50% compared to the wild type. When this change was introduced into the RK2 genome, decreases in transfer frequency of up to three orders of magnitude were observed, with bigger effects when Escherichia coli was the donor compared to Pseudomonas putida. Western blotting showed a significant decrease in Trb protein levels. These effects were much greater than the effect of the mutation on repression by TrbA alone. When KorB was introduced into the reporter system, the effects were closer to those observed in the whole RK2 context. These results indicate that co-operativity, previously observed between TrbA and KorB, allows big changes in transfer gene expression to result from small changes in individual regulator activities.


Assuntos
Proteínas de Bactérias/metabolismo , Conjugação Genética , Proteínas de Escherichia coli , Regulação Bacteriana da Expressão Gênica , Plasmídeos/genética , Proteínas Repressoras/genética , Proteínas de Bactérias/genética , Sequência de Bases , Genes Reporter , Dados de Sequência Molecular , Mutação , Regiões Operadoras Genéticas , Plasmídeos/metabolismo , Regiões Promotoras Genéticas , Proteínas Repressoras/metabolismo
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