scholarly journals Molecular and Phenotypic Characterization of Escherichia coli O26:H8 among Diarrheagenic E. coli O26 Strains Isolated in Brazil

2013 ◽  
Vol 79 (22) ◽  
pp. 6847-6854 ◽  
Author(s):  
Roxane M. F. Piazza ◽  
Sabine Delannoy ◽  
Patrick Fach ◽  
Halha O. Saridakis ◽  
Margareth Z. Pedroso ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ex Vivo ◽  
Effector Proteins ◽  
Phenotypic Characterization ◽  
Intestinal Biopsy ◽  
Content Type ◽  
E Coli ◽  
Flagellar Antigen ◽  
First Time

ABSTRACTEscherichia colistrains of serogroup O26 comprise two distinct groups of pathogens, characterized as enteropathogenicE. coli(EPEC) and enterohemorrhagicE. coli(EHEC). Among the several genes related to type III secretion system-secreted effector proteins,espKwas found to be highly specific for EHEC O26:H11 and itsstx-negative derivative strains isolated in European countries.E. coliO26 strains isolated in Brazil from infant diarrhea, foods, and the environment have consistently been shown to lackstxgenes 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 O26stx-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 forfliCH11, and 11 werefliCH8positive. The identification of genetic markers showed that several O26:H11 and all O26:H8 strains tested positive forespKand could therefore be discriminated as EHEC derivatives. The presence of H8 among EHEC O26 and itsstx-negative derivative isolates is described for the first time. The interaction of three isolates with polarized Caco-2 cells and with intestinal biopsy specimen fragmentsex vivoconfirmed 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 ofstx-negative O26 isolates within the same serotype helped to avoid misclassification of isolates, which certainly has important implications for public health surveillance.

scholarly journals Identification and Characterization of a Novel FosA7 Member from Fosfomycin-Resistant Escherichia coli Clinical Isolates from Canadian Hospitals

2020 ◽  
Vol 65 (1) ◽  
pp. e00865-20
Author(s):  
Kieran A. Milner ◽  
Denice C. Bay ◽  
David Alexander ◽  
Andrew Walkty ◽  
James A. Karlowsky ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Clinical Isolates ◽  
Phenotypic Characterization ◽  
Content Type ◽  
E Coli ◽  
Fosfomycin Resistance ◽  
Identification And Characterization

ABSTRACTHere, we characterize the fosA genes from three Escherichia coli clinical isolates recovered from Canadian patients. Each fosA sequence was individually overexpressed in E. coli BW25113, and antimicrobial susceptibility testing was performed to assess their role in fosfomycin resistance. The findings from this study identify and functionally characterize FosA3, FosA8, and novel FosA7 members and highlight the importance of phenotypic characterization of fosA genes.

scholarly journals Identification and Characterization of Genes Required for 5-Hydroxyuridine Synthesis in Bacillus subtilis and Escherichia coli tRNA

2019 ◽  
Vol 201 (20) ◽  
Author(s):  
Charles T. Lauhon
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Genomic Context ◽  
Similar Reduction ◽  
Content Type ◽  
E Coli ◽  
Wobble Position ◽  
Fertile Ground ◽  
And Function

ABSTRACT In bacteria, tRNAs that decode 4-fold degenerate family codons and have uridine at position 34 of the anticodon are typically modified with either 5-methoxyuridine (mo5U) or 5-methoxycarbonylmethoxyuridine (mcmo5U). These modifications are critical for extended recognition of some codons at the wobble position. Whereas the alkylation steps of these modifications have been described, genes required for the hydroxylation of U34 to give 5-hydroxyuridine (ho5U) remain unknown. Here, a number of genes in Escherichia coli and Bacillus subtilis are identified that are required for wild-type (wt) levels of ho5U. The yrrMNO operon is identified in B. subtilis as important for the biosynthesis of ho5U. Both yrrN and yrrO are homologs to peptidase U32 family genes, which includes the rlhA gene required for ho5C synthesis in E. coli. Deletion of either yrrN or yrrO, or both, gives a 50% reduction in mo5U tRNA levels. In E. coli, yegQ was found to be the only one of four peptidase U32 genes involved in ho5U synthesis. Interestingly, this mutant shows the same 50% reduction in (m)cmo5U as that observed for mo5U in the B. subtilis mutants. By analyzing the genomic context of yegQ homologs, the ferredoxin YfhL is shown to be required for ho5U synthesis in E. coli to the same extent as yegQ. Additional genes required for Fe-S biosynthesis and biosynthesis of prephenate give the same 50% reduction in modification. Together, these data suggest that ho5U biosynthesis in bacteria is similar to that of ho5C, but additional genes and substrates are required for complete modification. IMPORTANCE Modified nucleotides in tRNA serve to optimize both its structure and function for accurate translation of the genetic code. The biosynthesis of these modifications has been fertile ground for uncovering unique biochemistry and metabolism in cells. In this work, genes that are required for a novel anaerobic hydroxylation of uridine at the wobble position of some tRNAs are identified in both Bacillus subtilis and Escherichia coli. These genes code for Fe-S cluster proteins, and their deletion reduces the levels of the hydroxyuridine by 50% in both organisms. Additional genes required for Fe-S cluster and prephenate biosynthesis and a previously described ferredoxin gene all display a similar reduction in hydroxyuridine levels, suggesting that still other genes are required for the modification.

scholarly journals Molecular Characterization of Commensal Escherichia coli Adapted to Different Compartments of the Porcine Gastrointestinal Tract

2012 ◽  
Vol 78 (19) ◽  
pp. 6799-6803 ◽  
Author(s):  
Sam Abraham ◽  
David M. Gordon ◽  
James Chin ◽  
Huub J. M. Brouwers ◽  
Peter Njuguna ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gastrointestinal Tract ◽  
Random Amplified Polymorphic Dna ◽  
Content Type ◽  
E Coli ◽  
Plasmid Replicon ◽  
Different Strains ◽  
Different Characteristics

ABSTRACTThe role ofEscherichia colias a pathogen has been the focus of considerable study, while much less is known about it as a commensal and how it adapts to and colonizes different environmental niches within the mammalian gut. In this study, we characterizeEscherichia coliorganisms (n= 146) isolated from different regions of the intestinal tracts of eight pigs (dueodenum, ileum, colon, and feces). The isolates were typed using the method of random amplified polymorphic DNA (RAPD) and screened for the presence of bacteriocin genes and plasmid replicon types. Molecular analysis of variance using the RAPD data showed thatE. coliisolates are nonrandomly distributed among different gut regions, and that gut region accounted for 25% (P< 0.001) of the observed variation among strains. Bacteriocin screening revealed that a bacteriocin gene was detected in 45% of the isolates, with 43% carrying colicin genes and 3% carrying microcin genes. Of the bacteriocins observed (H47, E3, E1, E2, E7, Ia/Ib, and B/M), the frequency with which they were detected varied with respect to gut region for the colicins E2, E7, Ia/Ib, and B/M. The plasmid replicon typing gave rise to 25 profiles from the 13 Inc types detected. Inc F types were detected most frequently, followed by Inc HI1 and N types. Of the Inc types detected, 7 were nonrandomly distributed among isolates from the different regions of the gut. The results of this study indicate that not only may the different regions of the gastrointestinal tract harbor different strains ofE. colibut also that strains from different regions have different characteristics.

scholarly journals Cooperative Immune Suppression by Escherichia coli and Shigella Effector Proteins

2018 ◽  
Vol 86 (4) ◽  
Author(s):  
Maarten F. de Jong ◽  
Neal M. Alto
Keyword(s):  
Escherichia Coli ◽  
Defense Mechanisms ◽  
Immune Defense ◽  
Effector Proteins ◽  
Innate Immune ◽  
Host Cells ◽  
Secretion Systems ◽  
Content Type ◽  
E Coli ◽  
Type Iii Secretion Systems

ABSTRACT The enteric attaching and effacing (A/E) pathogens enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) and the invasive pathogens enteroinvasive E. coli (EIEC) and Shigella encode type III secretion systems (T3SS) used to inject effector proteins into human host cells during infection. Among these are a group of effectors required for NF-κB-mediated host immune evasion. Recent studies have identified several effector proteins from A/E pathogens and EIEC/ Shigella that are involved in suppression of NF-κB and have uncovered their cellular and molecular functions. A novel mechanism among these effectors from both groups of pathogens is to coordinate effector function during infection. This cooperativity among effector proteins explains how bacterial pathogens are able to effectively suppress innate immune defense mechanisms in response to diverse classes of immune receptor signaling complexes (RSCs) stimulated during infection.

scholarly journals Spread of NDM-5 and OXA-181 Carbapenemase-Producing Escherichia coli in Chad

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Oumar Ouchar Mahamat ◽  
Manon Lounnas ◽  
Mallorie Hide ◽  
Abelsalam Tidjani ◽  
Julio Benavides ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Healthy Volunteers ◽  
Resistance Genes ◽  
Sequence Type ◽  
Hospitalized Patients ◽  
Content Type ◽  
E Coli ◽  
First Time

ABSTRACT We detected for the first time blaNDM-5 and blaOXA-181 in Escherichia coli isolates from hospitalized patients and healthy volunteers in Chad. These resistance genes were located on IncX3 and IncF plasmids. Despite the large diversity of E. coli clones, the identified resistant intestinal isolates belonged mainly to the same sequence type.

scholarly journals Characteristics of Emerging Human-Pathogenic Escherichia coli O26:H11 Strains Isolated in France between 2010 and 2013 and Carrying thestx2dGene Only

2014 ◽  
Vol 53 (2) ◽  
pp. 486-492 ◽  
Author(s):  
Sabine Delannoy ◽  
Patricia Mariani-Kurkdjian ◽  
Stephane Bonacorsi ◽  
Sandrine Liguori ◽  
Patrick Fach
Keyword(s):  
Escherichia Coli ◽  
Virulence Gene ◽  
Gene Profiling ◽  
Content Type ◽  
E Coli ◽  
Negative Results ◽  
Pathogenic Escherichia Coli ◽  
Short Palindromic Repeat ◽  
Uremic Syndrome ◽  
First Time

Strains ofEscherichia coliO26:H11 that were positive forstx2alone (n= 23), which were not epidemiologically related or part of an outbreak, were isolated from pediatric patients in France between 2010 and 2013. We were interested in comparing these strains with the new highly virulentstx2a-positiveE. coliO26 clone sequence type 29 (ST29) that has emerged recently in Europe, and we tested them by multilocus sequence typing (MLST),stx2subtyping, clustered regularly interspaced short palindromic repeat (CRISPR) sequencing, and plasmid (ehxA,katP,espP, andetpD) and chromosomal (Z2098,espK, andespV) virulence gene profiling. We showed that 16 of the 23 strains appeared to correspond to this new clone, but the characteristics of 12 strains differed significantly from the previously described characteristics, with negative results for both plasmid and chromosomal genetic markers. These 12 strains exhibited a ST29 genotype and related CRISPR arrays (CRISPR2a alleles 67 or 71), suggesting that they evolved in a common environment. This finding was corroborated by the presence ofstx2din 7 of the 12 ST29 strains. This is the first time thatE. coliO26:H11 carryingstx2dhas been isolated from humans. This is additional evidence of the continuing evolution of virulent Shiga toxin-producingE. coli(STEC) O26 strains. A new O26:H11 CRISPR PCR assay, SP_O26_E, has been developed for detection of these 12 particular ST29 strains ofE. coliO26:H11. This test is useful to better characterize thestx2-positive O26:H11 clinical isolates, which are associated with severe clinical outcomes such as bloody diarrhea and hemolytic uremic syndrome.

scholarly journals Resistance Profiling and Molecular Characterization of Extended-Spectrum/Plasmid-Mediated AmpC β-Lactamase-Producing Escherichia coli Isolated from Healthy Broiler Chickens in South Korea

2020 ◽  
Vol 8 (9) ◽  
pp. 1434 ◽  
Author(s):  
Hyun-Ju Song ◽  
Dong Chan Moon ◽  
Abraham Fikru Mechesso ◽  
Hee Young Kang ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Phylogenetic Analysis ◽  
Resistance Gene ◽  
Broiler Chickens ◽  
Human Consumption ◽  
E Coli ◽  
Extended Spectrum ◽  
First Time ◽  
Pfge Profiles

We aimed to identify and characterize extended-spectrum β-lactamase (ESBL)-and/or plasmid-mediated AmpC β-lactamase (pAmpC)-producing Escherichia coli isolated from healthy broiler chickens slaughtered for human consumption in Korea. A total of 332 E. coli isolates were identified from 339 cloacal swabs in 2019. More than 90% of the isolates were resistant to multiple antimicrobials. ESBL/pAmpC-production was noted in 14% (46/332) of the isolates. Six of the CTX-M-β-lactamase-producing isolates were found to co-harbor at least one plasmid-mediated quinolone resistance gene. We observed the co-existence of blaCMY-2 and mcr-1 genes in the same isolate for the first time in Korea. Phylogenetic analysis demonstrated that the majority of blaCMY-2-carrying isolates belonged to subgroup D. Conjugation confirmed the transferability of blaCTX-M and blaCMY-2 genes, as well as non-β-lactam resistance traits from 60.9% (28/46) of the ESBL/pAmpC-producing isolates to a recipient E. coli J53. The ISECP, IS903, and orf477 elements were detected in the upstream or downstream regions. The blaCTX-M and blaCMY-2 genes mainly belonged to the IncI1, IncHI2, and/or IncFII plasmids. Additionally, the majority of ESBL/pAmpC-producing isolates exhibited heterogeneous PFGE profiles. This study showed that healthy chickens act as reservoirs of ESBL/pAmpC-producing E. coli that can potentially be transmitted to humans.

scholarly journals Characterization of Multidrug-Resistant Escherichia coli Isolates from Animals Presenting at a University Veterinary Hospital

2011 ◽  
Vol 77 (20) ◽  
pp. 7104-7112 ◽  
Author(s):  
Maria Karczmarczyk ◽  
Yvonne Abbott ◽  
Ciara Walsh ◽  
Nola Leonard ◽  
Séamus Fanning
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Gene Array ◽  
Multidrug Resistant ◽  
Genetic Determinants ◽  
Gene Encoding ◽  
Content Type ◽  
E Coli ◽  
Class 1

ABSTRACTIn this study, we examined molecular mechanisms associated with multidrug resistance (MDR) in a collection ofEscherichia coliisolates recovered from hospitalized animals in Ireland. PCR and DNA sequencing were used to identify genes associated with resistance. Class 1 integrons were prevalent (94.6%) and contained gene cassettes recognized previously and implicated mainly in resistance to aminoglycosides, β-lactams, and trimethoprim (aadA1,dfrA1-aadA1,dfrA17-aadA5,dfrA12-orfF-aadA2,blaOXA-30-aadA1,aacC1-orf1-orf2-aadA1,dfr7). Class 2 integrons (13.5%) contained thedfrA1-sat1-aadA1gene array. The most frequently occurring phenotypes included resistance to ampicillin (97.3%), chloramphenicol (75.4%), florfenicol (40.5%), gentamicin (54%), neomycin (43.2%), streptomycin (97.3%), sulfonamide (98.6%), and tetracycline (100%). The associated resistance determinants detected includedblaTEM,cat,floR,aadB,aphA1,strA-strB,sul2, andtet(B), respectively. TheblaCTX-M-2gene, encoding an extended-spectrum β-lactamase (ESβL), andblaCMY-2, encoding an AmpC-like enzyme, were identified in 8 and 18 isolates, respectively. The mobility of the resistance genes was demonstrated using conjugation assays with a representative selection of isolates. High-molecular-weight plasmids were found to be responsible for resistance to multiple antimicrobial compounds. The study demonstrated that animal-associated commensalE. coliisolates possess a diverse repertoire of transferable genetic determinants. Emergence of ESβLs and AmpC-like enzymes is particularly significant. To our knowledge, theblaCTX-M-2gene has not previously been reported in Ireland.

scholarly journals Characterization of the New AmpC β-Lactamase FOX-8 Reveals a Single Mutation, Phe313Leu, Located in the R2 Loop That Affects Ceftazidime Hydrolysis

2013 ◽  
Vol 57 (10) ◽  
pp. 5158-5161 ◽  
Author(s):  
Francisco José Pérez-Llarena ◽  
Frédéric Kerff ◽  
Laura Zamorano ◽  
María Carmen Fernández ◽  
Maria Luz Nuñez ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Kinetic Analysis ◽  
Clinical Strain ◽  
Single Mutation ◽  
Content Type ◽  
E Coli ◽  
Fold Reduction ◽  
Class C

ABSTRACTA novel class C β-lactamase (FOX-8) was isolated from a clinical strain ofEscherichia coli. The FOX-8 enzyme possessed a unique substitution (Phe313Leu) compared to FOX-3. IsogenicE. colistrains carrying FOX-8 showed an 8-fold reduction in resistance to ceftazidime relative to FOX-3. In a kinetic analysis, FOX-8 displayed a 33-fold reduction inkcat/Kmfor ceftazidime compared to FOX-3. In the FOX family of β-lactamases, the Phe313 residue located in the R2 loop affects ceftazidime hydrolysis and alters the phenotype ofE. colistrains carrying this variant.

scholarly journals Characterization of a Novel Pyranopyridine Inhibitor of the AcrAB Efflux Pump of Escherichia coli

2013 ◽  
Vol 58 (2) ◽  
pp. 722-733 ◽  
Author(s):  
Timothy J. Opperman ◽  
Steven M. Kwasny ◽  
Hong-Suk Kim ◽  
Son T. Nguyen ◽  
Chad Houseweart ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Gram Negative ◽  
Content Type ◽  
E Coli ◽  
Resistance Nodulation Division ◽  
Rnd Efflux Pumps ◽  
Acrab Efflux Pump

ABSTRACTMembers of the resistance-nodulation-division (RND) family of efflux pumps, such as AcrAB-TolC ofEscherichia coli, play major roles in multidrug resistance (MDR) in Gram-negative bacteria. A strategy for combating MDR is to develop efflux pump inhibitors (EPIs) for use in combination with an antibacterial agent. Here, we describe MBX2319, a novel pyranopyridine EPI with potent activity against RND efflux pumps of theEnterobacteriaceae. MBX2319 decreased the MICs of ciprofloxacin (CIP), levofloxacin, and piperacillin versusE. coliAB1157 by 2-, 4-, and 8-fold, respectively, but did not exhibit antibacterial activity alone and was not active against AcrAB-TolC-deficient strains. MBX2319 (3.13 μM) in combination with 0.016 μg/ml CIP (minimally bactericidal) decreased the viability (CFU/ml) ofE. coliAB1157 by 10,000-fold after 4 h of exposure, in comparison with 0.016 μg/ml CIP alone. In contrast, phenyl-arginine-β-naphthylamide (PAβN), a known EPI, did not increase the bactericidal activity of 0.016 μg/ml CIP at concentrations as high as 100 μM. MBX2319 increased intracellular accumulation of the fluorescent dye Hoechst 33342 in wild-type but not AcrAB-TolC-deficient strains and did not perturb the transmembrane proton gradient. MBX2319 was broadly active againstEnterobacteriaceaespecies andPseudomonas aeruginosa. MBX2319 is a potent EPI with possible utility as an adjunctive therapeutic agent for the treatment of infections caused by Gram-negative pathogens.

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