Genomic Avenue to Avian Colisepticemia

ABSTRACTHere we present an extensive genomic and genetic analysis of Escherichia coli strains of serotype O78 that represent the major cause of avian colisepticemia, an invasive infection caused by avian pathogenicEscherichia coli(APEC) strains. It is associated with high mortality and morbidity, resulting in significant economic consequences for the poultry industry. To understand the genetic basis of the virulence of avian septicemic E. coli, we sequenced the entire genome of a clinical isolate of serotype O78—O78:H19 ST88 isolate 789 (O78-9)—and compared it with three publicly available APEC O78 sequences and one complete genome of APEC serotype O1 strain. Although there was a large variability in genome content between the APEC strains, several genes were conserved, which are potentially critical for colisepticemia. Some of these genes are present in multiple copies per genome or code for gene products with overlapping function, signifying their importance. A systematic deletion of each of these virulence-related genes identified three systems that are conserved in all septicemic strains examined and are critical for serum survival, a prerequisite for septicemia. These are the plasmid-encoded protein, the defective ETT2 (E. colitype 3 secretion system 2) type 3 secretion system ETT2sepsis, and iron uptake systems. Strain O78-9 is the only APEC O78 strain that also carried the regulon coding for yersiniabactin, the iron binding system of theYersiniahigh-pathogenicity island. Interestingly, this system is the only one that cannot be complemented by other iron uptake systems under iron limitation and in serum.IMPORTANCEAvian colisepticemia is a severe systemic disease of birds causing high morbidity and mortality and resulting in severe economic losses. The bacteria associated with avian colisepticemia are highly antibiotic resistant, making antibiotic treatment ineffective, and there is no effective vaccine due to the multitude of serotypes involved. To understand the disease and work out strategies to combat it, we performed an extensive genomic and genetic analysis of Escherichia coli strains of serotype O78, the major cause of the disease. We identified several potential virulence factors, conserved in all the colisepticemic strains examined, and determined their contribution to growth in serum, an absolute requirement for septicemia. These findings raise the possibility that specific vaccines or drugs can be developed against these critical virulence factors to help combat this economically important disease.

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Control freaks—signals and cues governing the regulation of virulence in attaching and effacing pathogens

Biochemical Society Transactions ◽

10.1042/bst20180546 ◽

2018 ◽

Vol 47 (1) ◽

pp. 229-238 ◽

Cited By ~ 7

Author(s):

Natasha C.A. Turner ◽

James P.R. Connolly ◽

Andrew J. Roe

Keyword(s):

Escherichia Coli ◽

Transcriptional Regulation ◽

Virulence Factors ◽

Secretion System ◽

Master Regulators ◽

Enterohaemorrhagic Escherichia Coli ◽

Type 3 Secretion System ◽

Enterocyte Effacement ◽

Type 3 ◽

Fine Tune

AbstractEnterohaemorrhagic Escherichia coli (EHEC) mediates disease using a type 3 secretion system (T3SS), which is encoded on the locus of enterocyte effacement (LEE) and is tightly controlled by master regulators. This system is further modulated by a number of signals that help to fine-tune virulence, including metabolic, environmental and chemical signals. Since the LEE and its master regulator, Ler, were established, there have been numerous scientific advancements in understanding the regulation and expression of virulence factors in EHEC. This review will discuss the recent advancements in this field since our previous review, with a focus on the transcriptional regulation of the LEE.

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The Repeat-In-Toxin Family Member TosA Mediates Adherence of Uropathogenic Escherichia coli and Survival during Bacteremia

Infection and Immunity ◽

10.1128/iai.05713-11 ◽

2011 ◽

Vol 80 (2) ◽

pp. 493-505 ◽

Cited By ~ 31

Author(s):

Patrick D. Vigil ◽

Travis J. Wiles ◽

Michael D. Engstrom ◽

Lev Prasov ◽

Matthew A. Mulvey ◽

...

Keyword(s):

Escherichia Coli ◽

Urinary Tract ◽

Virulence Factors ◽

Upper Urinary Tract ◽

Host Cells ◽

Content Type ◽

E Coli ◽

Wide Range ◽

Novel Target ◽

Tract Infections

ABSTRACTUropathogenicEscherichia coli(UPEC) is responsible for the majority of uncomplicated urinary tract infections (UTI) and represents the most common bacterial infection in adults. UPEC utilizes a wide range of virulence factors to colonize the host, including the novel repeat-in-toxin (RTX) protein TosA, which is specifically expressed in the host urinary tract and contributes significantly to the virulence and survival of UPEC.tosA, found in strains within the B2 phylogenetic subgroup ofE. coli, serves as a marker for strains that also contain a large number of well-characterized UPEC virulence factors. The presence oftosAin anE. coliisolate predicts successful colonization of the murine model of ascending UTI, regardless of the source of the isolate. Here, a detailed analysis of the function oftosArevealed that this gene is transcriptionally linked to genes encoding a conserved type 1 secretion system similar to other RTX family members. TosA localized to the cell surface and was found to mediate (i) adherence to host cells derived from the upper urinary tract and (ii) survival in disseminated infections and (iii) to enhance lethality during sepsis (as assessed in two different animal models of infection). An experimental vaccine, using purified TosA, protected vaccinated animals against urosepsis. From this work, it was concluded that TosA belongs to a novel group of RTX proteins that mediate adherence and host damage during UTI and urosepsis and could be a novel target for the development of therapeutics to treat ascending UTIs.

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Bioinformatic and Molecular Analysis of Inverse Autotransporters from Escherichia coli

mSphere ◽

10.1128/msphere.00572-19 ◽

2019 ◽

Vol 4 (4) ◽

Cited By ~ 3

Author(s):

Kelvin G. K. Goh ◽

Danilo G. Moriel ◽

Steven J. Hancock ◽

Minh-Duy Phan ◽

Mark A. Schembri

Keyword(s):

Escherichia Coli ◽

Cell Surface ◽

Biofilm Formation ◽

Secretion System ◽

Content Type ◽

E Coli ◽

Wide Range ◽

Type V Secretion ◽

K 12 ◽

Type V

ABSTRACT Proteins secreted by the type V secretion system possess multiple functions, including the capacity to mediate adhesion, aggregation, and biolfilm formation. The type V secretion system can be divided into five subclasses, one of which is the type Ve system. Proteins of the type Ve secretion system are also referred to as inverse autotransporters (IATs). In this study, we performed an in silico analysis of 126 completely sequenced Escherichia coli genomes available in the NCBI database and identified several distinct IAT-encoding gene families whose distribution varied throughout the E. coli phylogeny. The genes included three characterized IATs (intimin, fdeC, and yeeJ) and four uncharacterized IATs (here named iatA, iatB, iatC, and iatD). The four iat genes were cloned from the completely sequenced environmental E. coli strain SMS-3-5 and characterized. Three of these IAT proteins (IatB, IatC, and IatD) were expressed at the cell surface and possessed the capacity to mediate biofilm formation in a recombinant E. coli K-12 strain. Further analysis of the iatB gene, which showed a unique association with extraintestinal E. coli strains, suggested that its regulation is controlled by the LeuO global regulator. Overall, this study provides new data describing the prevalence, sequence variation, domain structure, function, and regulation of IATs found in E. coli. IMPORTANCE Escherichia coli is one of the most prevalent facultative anaerobes of the human gut. E. coli normally exists as a harmless commensal but can also cause disease following the acquisition of genes that enhance its pathogenicity. Adhesion is an important first step in colonization of the host and is mediated by an array of cell surface components. In E. coli, these include a family of adhesins secreted by the type V secretion system. Here, we identified and characterized new proteins from an emerging subclass of the type V secretion system known as the inverse autotransporters (IATs). We found that IAT-encoding genes are present in a wide range of strains and showed that three novel IATs were localized on the E. coli cell surface and mediated biofilm formation. Overall, this study provides new insight into the prevalence, function, and regulation of IATs in E. coli.

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Fur-Dam Regulatory Interplay at an Internal Promoter of the Enteroaggregative Escherichia coli Type VI Secretion sci1 Gene Cluster

Journal of Bacteriology ◽

10.1128/jb.00075-20 ◽

2020 ◽

Vol 202 (10) ◽

Cited By ~ 3

Author(s):

Yannick R. Brunet ◽

Christophe S. Bernard ◽

Eric Cascales

Keyword(s):

Escherichia Coli ◽

Gene Cluster ◽

Gene Clusters ◽

Secretion System ◽

Target Cells ◽

Type Vi Secretion System ◽

Content Type ◽

Internal Promoter ◽

E Coli ◽

Type Vi Secretion

ABSTRACT The type VI secretion system (T6SS) is a weapon for delivering effectors into target cells that is widespread in Gram-negative bacteria. The T6SS is a highly versatile machine, as it can target both eukaryotic and prokaryotic cells, and it has been proposed that T6SSs are adapted to the specific needs of each bacterium. The expression of T6SS gene clusters and the activation of the secretion apparatus are therefore tightly controlled. In enteroaggregative Escherichia coli (EAEC), the sci1 T6SS gene cluster is subject to a complex regulation involving both the ferric uptake regulator (Fur) and DNA adenine methylase (Dam)-dependent DNA methylation. In this study, an additional, internal, promoter was identified within the sci1 gene cluster using +1 transcriptional mapping. Further analyses demonstrated that this internal promoter is controlled by a mechanism strictly identical to that of the main promoter. The Fur binding box overlaps the −10 transcriptional element and a Dam methylation site, GATC-32. Hence, the expression of the distal sci1 genes is repressed and the GATC-32 site is protected from methylation in iron-rich conditions. The Fur-dependent protection of GATC-32 was confirmed by an in vitro methylation assay. In addition, the methylation of GATC-32 negatively impacted Fur binding. The expression of the sci1 internal promoter is therefore controlled by iron availability through Fur regulation, whereas Dam-dependent methylation maintains a stable ON expression in iron-limited conditions. IMPORTANCE Bacteria use weapons to deliver effectors into target cells. One of these weapons, the type VI secretion system (T6SS), assembles a contractile tail acting as a spring to propel a toxin-loaded needle. Its expression and activation therefore need to be tightly regulated. Here, we identified an internal promoter within the sci1 T6SS gene cluster in enteroaggregative E. coli. We show that this internal promoter is controlled by Fur and Dam-dependent methylation. We further demonstrate that Fur and Dam compete at the −10 transcriptional element to finely tune the expression of T6SS genes. We propose that this elegant regulatory mechanism allows the optimum production of the T6SS in conditions where enteroaggregative E. coli encounters competing species.

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Relative Fecal Abundance of Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains and Their Occurrence in Urinary Tract Infections in Women

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00238-13 ◽

2013 ◽

Vol 57 (9) ◽

pp. 4512-4517 ◽

Cited By ~ 58

Author(s):

Etienne Ruppé ◽

Brandusa Lixandru ◽

Radu Cojocaru ◽

Çağrı Büke ◽

Elisabeth Paramythiotou ◽

...

Keyword(s):

Escherichia Coli ◽

Urinary Tract ◽

Virulence Factors ◽

Urinary Tract Infections ◽

Predictive Values ◽

Content Type ◽

Extended Spectrum Beta Lactamase ◽

E Coli ◽

Extended Spectrum ◽

Tract Infections

ABSTRACTExtended-spectrum-beta-lactamase (ESBL)-producingEscherichia coli(ESBLE. coli) strains are of major concern because few antibiotics remain active against these bacteria. We investigated the association between the fecal relative abundance (RA) of ESBL-producingE. coli(ESBL-RA) and the occurrence of ESBLE. coliurinary tract infections (UTIs). The first stool samples passed after suspicion of UTI from 310 women with subsequently confirmedE. coliUTIs were sampled and tested for ESBL-RA by culture on selective agar. Predictive values of ESBL-RA for ESBLE. coliUTI were analyzed for women who were not exposed to antibiotics when the stool was passed. ESBLE. coliisolates were characterized for ESBL type, phylogroup, relatedness, and virulence factors. The prevalence of ESBLE. colifecal carriage was 20.3%, with ESBLE. coliUTIs being present in 12.3% of the women. The mean ESBL-RA (95% confidence interval [CI]) was 13-fold higher in women exposed to antibiotics at the time of sampling than in those not exposed (14.3% [range, 5.6% to 36.9%] versus 1.1% [range, 0.32% to 3.6%], respectively;P< 0.001) and 18-fold higher in women with ESBLE. coliUTI than in those with anotherE. coliUTI (10.0% [range, 0.54% to 100%] versus 0.56% [range, 0.15% to 2.1%[, respectively;P< 0.05). An ESBL-RA of <0.1% was 100% predictive of a non-ESBLE. coliUTI. ESBL type, phylogroup, relatedness, and virulence factors were not found to be associated with ESBL-RA. In conclusion, ESBL-RA was linked to the occurrence of ESBLE. coliUTI in women who were not exposed to antibiotics and who had the same clone ofE. coliin urine samples and fecal samples. Especially, a low ESBL-RA appeared to be associated with a low risk of ESBLE. coliinfection.

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Regulation by ToxR-Like Proteins Converges onvttRBExpression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae

Journal of Bacteriology ◽

10.1128/jb.00130-16 ◽

2016 ◽

Vol 198 (11) ◽

pp. 1675-1682 ◽

Cited By ~ 6

Author(s):

Kelly A. Miller ◽

Madeline K. Sofia ◽

Jacob W. A. Weaver ◽

Christopher H. Seward ◽

Michelle Dziejman

Keyword(s):

Gene Expression ◽

Cell Death ◽

Vibrio Cholerae ◽

Secretion System ◽

Content Type ◽

Transcriptional Regulatory ◽

Type 3 Secretion System ◽

Type 3

ABSTRACTGenes carried on the type 3 secretion system (T3SS) pathogenicity island ofVibrio choleraenon-O1/non-O139 serogroup strain AM-19226 must be precisely regulated in order for bacteria to cause disease. Previously reported results showed that both T3SS function and the presence of bile are required to cause Caco2-BBE cell cytotoxicity during coculture with strain AM-19226. We therefore investigated additional parameters affectingin vitrocell death, including bacterial load and the role of three transmembrane transcriptional regulatory proteins, VttRA, VttRB, and ToxR. VttRAand VttRBare encoded on the horizontally acquired T3SS genomic island, whereas ToxR is encoded on the ancestral chromosome. While strains carrying deletions in any one of the three transcriptional regulatory genes are unable to cause eukaryotic cell death, the results of complementation studies point to a hierarchy of regulatory control that converges onvttRBexpression. The data suggest both that ToxR and VttRAact upstream of VttRBand that modifying the level of eithervttRAorvttRBexpression can strongly influence T3SS gene expression. We therefore propose a model whereby T3SS activity and, hence,in vitrocytotoxicity are ultimately regulated byvttRBexpression.IMPORTANCEIn contrast to O1 and O139 serogroupV. choleraestrains that cause cholera using two main virulence factors (toxin-coregulated pilus [TCP] and cholera toxin [CT]), O39 serogroup strain AM-19226 uses a type 3 secretion system as its principal virulence mechanism. Although the regulatory network governing TCP and CT expression is well understood, the factors influencing T3SS-associated virulence are not. Using anin vitromammalian cell model to investigate the role of three ToxR-like transmembrane transcriptional activators in causing T3SS-dependent cytotoxicity, we found that expression levels and a hierarchical organization were important for promoting T3SS gene expression. Furthermore, our results suggest that horizontally acquired, ToxR-like proteins act in concert with the ancestral ToxR protein to orchestrate T3SS-mediated pathogenicity.

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Escherichia coli Isolates That Carryvat,fyuA,chuA, andyfcVEfficiently Colonize the Urinary Tract

Infection and Immunity ◽

10.1128/iai.00752-12 ◽

2012 ◽

Vol 80 (12) ◽

pp. 4115-4122 ◽

Cited By ~ 90

Author(s):

Rachel R. Spurbeck ◽

Paul C. Dinh ◽

Seth T. Walk ◽

Ann E. Stapleton ◽

Thomas M. Hooton ◽

...

Keyword(s):

Escherichia Coli ◽

Urinary Tract Infection ◽

Urinary Tract ◽

Tract Infection ◽

Virulence Factors ◽

Neonatal Meningitis ◽

Content Type ◽

E Coli ◽

Core Set ◽

Encoding Genes

ABSTRACTExtraintestinalEscherichia coli(ExPEC), a heterogeneous group of pathogens, encompasses avian, neonatal meningitis, and uropathogenicE. colistrains. While several virulence factors are associated with ExPEC, there is no core set of virulence factors that can be used to definitively differentiate these pathotypes. Here we describe a multiplex of four virulence factor-encoding genes,yfcV,vat,fyuA, andchuA, highly associated with uropathogenicE. colistrains that can distinguish three groups ofE. coli: diarrheagenic and animal-associatedE. colistrains, human commensal and avian pathogenicE. colistrains, and uropathogenic and neonatal meningitisE. colistrains. Furthermore, human intestinal isolates that encode all four predictor genes express them during exponential growth in human urine and colonize the bladder in the mouse model of ascending urinary tract infection in higher numbers than human commensal strains that do not encode the four predictor genes (P= 0.02), suggesting that the presence of the predictors correlates with uropathogenic potential.

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Complete Genome Sequence of Pseudomonas aeruginosa CMC-115, a Clinical Strain from an Acute Ventilator-Associated Pneumonia Patient

Microbiology Resource Announcements ◽

10.1128/mra.00595-20 ◽

2020 ◽

Vol 9 (30) ◽

Author(s):

Adenike Adenikinju ◽

Roderick V. Jensen ◽

Thomas M. Kerkering ◽

Dorothy C. Garner ◽

Jayasimha Rao

Keyword(s):

Pseudomonas Aeruginosa ◽

Complete Genome ◽

Secretion System ◽

Clinical Strain ◽

Ventilator Associated Pneumonia ◽

Circular Chromosome ◽

Content Type ◽

Pneumonia Patient ◽

Type 3 Secretion System ◽

Type 3

ABSTRACT We report the complete genome of clinical strain Pseudomonas aeruginosa CMC-115, which was isolated from an acute ventilator-associated pneumonia patient. Illumina sequencing reads were assembled using Geneious to yield a 6,375,262-bp circular chromosome that exhibited an unusual ferrichrome receptor in the pyoverdine synthesis locus and the absence of type 3 secretion system genes.

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Response of Pseudomonas aeruginosa to the Innate Immune System-Derived Oxidants Hypochlorous Acid and Hypothiocyanous Acid

Journal of Bacteriology ◽

10.1128/jb.00300-20 ◽

2020 ◽

Vol 203 (2) ◽

pp. e00300-20

Author(s):

Katie V. Farrant ◽

Livia Spiga ◽

Jane C. Davies ◽

Huw D. Williams

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Antibiotic Resistance ◽

Immune System ◽

Hypochlorous Acid ◽

Secretion System ◽

Content Type ◽

Type 3 Secretion System ◽

Lung Infections ◽

Type 3

ABSTRACTPseudomonas aeruginosa is a significant nosocomial pathogen and is associated with lung infections in cystic fibrosis (CF). Once established, P. aeruginosa infections persist and are rarely eradicated despite host immune cells producing antimicrobial oxidants, including hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). There is limited knowledge as to how P. aeruginosa senses, responds to, and protects itself against HOCl and HOSCN and the contribution of such responses to its success as a CF pathogen. To investigate the P. aeruginosa response to these oxidants, we screened 707 transposon mutants, with mutations in regulatory genes, for altered growth following HOCl exposure. We identified regulators of antibiotic resistance, methionine biosynthesis, catabolite repression, and PA14_07340, the homologue of the Escherichia coli HOCl-sensor RclR (30% identical), which are required for protection against HOCl. We have shown that RclR (PA14_07340) protects specifically against HOCl and HOSCN stress and responds to both oxidants by upregulating the expression of a putative peroxiredoxin, rclX (PA14_07355). Transcriptional analysis revealed that while there was specificity in the response to HOCl (231 genes upregulated) and HOSCN (105 genes upregulated), there was considerable overlap, with 74 genes upregulated by both oxidants. These included genes encoding the type 3 secretion system, sulfur and taurine transport, and the MexEF-OprN efflux pump. RclR coordinates part of the response to both oxidants, including upregulation of pyocyanin biosynthesis genes, and, in the presence of HOSCN, downregulation of chaperone genes. These data indicate that the P. aeruginosa response to HOCl and HOSCN is multifaceted, with RclR playing an essential role.IMPORTANCE The bacterial pathogen Pseudomonas aeruginosa causes devastating infections in immunocompromised hosts, including chronic lung infections in cystic fibrosis patients. To combat infection, the host’s immune system produces the antimicrobial oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). Little is known about how P. aeruginosa responds to and survives attack from these oxidants. To address this, we carried out two approaches: a mutant screen and transcriptional study. We identified the P. aeruginosa transcriptional regulator, RclR, which responds specifically to HOCl and HOSCN stress and is essential for protection against both oxidants. We uncovered a link between the P. aeruginosa transcriptional response to these oxidants and physiological processes associated with pathogenicity, including antibiotic resistance and the type 3 secretion system.

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Detection of Virulence-Associated Genes in Escherichia coli O157 and Non-O157 Isolates from Beef Cattle, Humans, and Chickens

Journal of Food Protection ◽

10.4315/0362-028x-71.9.1774 ◽

2008 ◽

Vol 71 (9) ◽

pp. 1774-1784 ◽

Cited By ~ 11

Author(s):

BRIGITTE LEFEBVRE ◽

MOUSSA S. DIARRA ◽

HÉLÈNE MOISAN ◽

FRANÇOIS MALOUIN

Keyword(s):

Escherichia Coli ◽

Beef Cattle ◽

Broiler Chickens ◽

Animal Origin ◽

Pathogenic Potential ◽

Antibiotic Resistant ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

Type 3 Secretion System ◽

Type 3

Food-producing animals can be reservoirs of pathogenic Escherichia coli strains that can induce diseases in animals or humans. Contamination of food by E. coli O157:H7 raises immediate concerns about public health, although it is not clear whether all E. coli O157 isolates of animal origin are equally harmful to humans. Inversely, the pathogenic potential of atypical E. coli O157 isolates and several non-O157 serotypes often is ignored. We used a DNA microarray capable of detecting a subset of 346 genes to compare the virulence-associated genes present in eight E. coli O157 isolates from human cases, 14 antibiotic-resistant and/or hypermutable E. coli O157 isolates from beef cattle, and four antibiotic-resistant, sorbitol-negative, non-O157 E. coli isolates from healthy broiler chickens. Hybridization on arrays (HOA) revealed that O157 isolates from beef cattle and humans were genetically distinct, although they possessed most of the same subset of virulence genes. HOA allowed discrimination between hypermutable and antibiotic-resistant O157 isolates from beef cattle based on hybridization results for the stx2 and ycgG genes (hypermutable) or ymfL, stx1, stx2, and hlyEavian genes (resistant). However, the absence of hybridization to gene yfdR characterized human isolates. HOA also revealed that an atypical sorbitol-fermenting bovine O157 isolate lacked some genes of the type 3 secretion system, plasmid pO157, and the stx1 and stx2 genes. This isolate had a particular pathotype (eaeAβ tirα espAα espBα espDα) not found in typical E. coli O157:H7. HOA revealed that some non-O157 E. coli isolates from healthy chickens carried genes responsible for salmochelin- and yersiniabactin-mediated iron uptake generally associated with pathogenic strains.

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