Characterization of Helicobacter pylori tlyA and Its Association with Bacterial Density

ABSTRACT Motility of Helicobacter species has been shown to be essential for successful colonization of the host. We have investigated the organization of a flagellar export locus in Helicobacter pylori. A 7-kb fragment of the H. pylori CCUG 17874 genome was cloned and sequenced, revealing an operon comprising an open reading frame of unknown function (ORF03), essential housekeeping genes (ileS and murB), flagellar export genes (fliI and fliQ), and a homolog to a gene implicated in virulence factor transport in other pathogens (virB11). A promoter for this operon, showing similarity to the Escherichia coli ς70 consensus, was identified by primer extension. Cotranscription of the genes in the operon was demonstrated by reverse transcription-PCR, and transcription of virB11, fliI, fliQ, andmurB was detected in human or mouse biopsies obtained from infected hosts. The genetic organization of this locus was conserved in a panel of H. pylori clinical isolates. EngineeredfliI and fliQ mutant strains were completely aflagellate and nonmotile, whereas a virB11 mutant still produced flagella. The fliI and fliQ mutant strains produced reduced levels of flagellin and the hook protein FlgE. Production of OMP4, a member of the outer membrane protein family identified in H. pylori 26695, was reduced in both thevirB11 mutant and the fliI mutant, suggesting related functions of the virulence factor export protein (VirB11) and the flagellar export component (FliI).

Download Full-text

Efficacy of Clarithromycin Depends on the Bacterial Density in Clarithromycin-Heteroresistant Helicobacter pylori Infections: An In Situ Detected Susceptibility and Quantitative Morphometry-Based Retrospective Study

Pathology & Oncology Research ◽

10.3389/pore.2021.1609863 ◽

2021 ◽

Vol 27 ◽

Author(s):

Jewel Ju Ea Kim ◽

Ildikó Kocsmár ◽

György Miklós Buzás ◽

Ildikó Szirtes ◽

Orsolya Rusz ◽

...

Keyword(s):

Helicobacter Pylori ◽

Retrospective Study ◽

Bacterial Population ◽

Tissue Sample ◽

Bacterial Density ◽

Resistant Bacteria ◽

Hybridization Technique ◽

Predictive Role

The global rise in clarithromycin (Cla) resistance is considered to be the main contributor of Helicobacter pylori (Hp) eradication failures. In nearly half of the Cla-resistant Hp infections, Cla-susceptible bacteria are simultaneously present with the Cla-resistant ones (Cla-heteroresistance). The proportion of resistant bacteria in the bacterial population (R-fraction) and its predictive role for the use of Cla-based therapies in Cla-heteroresistant infections has not yet been investigated. Our retrospective study analyzed gastric biopsy samples of 62 Hp-positive patients with Cla-heteroresistant infection. Fluorescence In Situ Hybridization technique was used to visualize the coexistence of resistant and susceptible bacteria within one tissue sample. R-fraction was quantified on multichannel microimages by digital morphometry. Resistant bacteria had a patchy distribution within the whole bacterial population causing high diversity among the investigated areas. Patients were subdivided into two major groups according to whether a Cla-based eradication attempt was conducted before or after the biopsy sampling. R-fraction was significantly lower among cases having only one previous Cla-based eradication attempt vs. those that had multiple previous eradications, including at least one Cla-containing therapy (0.41 vs. 0.89, p = 0.0308). Majority of the patients without previous eradication attempt had successful eradication with Cla-containing regimen (59.26%), verified by a negative 13C-urea breath test or control biopsy. Multivariable model indicated that the therapeutic outcome using Cla-based regimens depended on the bacterial density rather than the R-fraction. Our study raises the potential use of Cla-containing eradication therapies in certain Cla-heteroresistant Hp infections, taking into account the possible predictive role of bacterial density.

Download Full-text

Genotypic Characterization of Clarithromycin-Resistant and -Susceptible Helicobacter pylori Strains from the Same Patient Demonstrates Existence of Two Unrelated Isolates

Journal of Clinical Microbiology ◽

10.1128/jcm.36.9.2730-2731.1998 ◽

1998 ◽

Vol 36 (9) ◽

pp. 2730-2731 ◽

Cited By ~ 10

Author(s):

Ge Wang ◽

Qin Jiang ◽

Diane E. Taylor

Keyword(s):

Helicobacter Pylori ◽

Gel Electrophoresis ◽

Genomic Dna ◽

Pulsed Field Gel Electrophoresis ◽

23S Rrna ◽

Rrna Gene ◽

Clarithromycin Resistance ◽

23S Rrna Gene ◽

Mode Of Development

Clarithromycin-susceptible and clarithromycin-resistantHelicobacter pylori isolates from the same patient were investigated for the mode of development and mechanism of clarithromycin resistance. The clarithromycin-resistant strain UA1182 harbors homozygous A-to-G mutations at position 2143 in both copies of the 23S rRNA gene and has a phenotype of resistance to clarithromycin and clindamycin but no significant resistance to streptogramin B. Pulsed-field gel electrophoresis patterns of NruI- andNotI-digested genomic DNA from the Clas and Clar isolates demonstrated that they are genetically distinct, suggesting that the development of clarithromycin resistance is not from the mutation of the existing Clas strain but from a completely new strain.

Download Full-text

Functional characterization of the antagonistic flagellar late regulators FliA and FlgM of Helicobacter pylori and their effects on the H. pylori transcriptome

Molecular Microbiology ◽

10.1046/j.1365-2958.2002.02765.x ◽

2002 ◽

Vol 43 (2) ◽

pp. 307-322 ◽

Cited By ~ 62

Author(s):

Christine Josenhans ◽

Eike Niehus ◽

Stefanie Amersbach ◽

Andrea Hörster ◽

Christian Betz ◽

...

Keyword(s):

Helicobacter Pylori ◽

Functional Characterization ◽

H Pylori

Download Full-text

Construction and characterization of recombinant attenuated Salmonella typhimurium expressing the babA2/ureI fusion gene of Helicobacter pylori

Clinics and Research in Hepatology and Gastroenterology ◽

10.1016/j.clinre.2011.06.007 ◽

2011 ◽

Vol 35 (10) ◽

pp. 655-660 ◽

Cited By ~ 5

Author(s):

Dong-sheng Liu ◽

Si-jun Hu ◽

Nan-jin Zhou ◽

Yong Xie ◽

Jun Cao

Keyword(s):

Helicobacter Pylori ◽

Salmonella Typhimurium ◽

Fusion Gene ◽

Attenuated Salmonella Typhimurium

Download Full-text

A Novel 3-Deoxy-d-manno-Octulosonic Acid (Kdo) Hydrolase That Removes the Outer Kdo Sugar of Helicobacter pylori Lipopolysaccharide

Journal of Bacteriology ◽

10.1128/jb.187.10.3374-3383.2005 ◽

2005 ◽

Vol 187 (10) ◽

pp. 3374-3383 ◽

Cited By ~ 34

Author(s):

Christopher Stead ◽

An Tran ◽

Donald Ferguson ◽

Sara McGrath ◽

Robert Cotter ◽

...

Keyword(s):

Helicobacter Pylori ◽

Lipid A ◽

In Vitro Assay ◽

Spectrometric Analysis ◽

Vitro Assay ◽

The Core ◽

H Pylori

ABSTRACT The lipid A domain anchors lipopolysaccharide (LPS) to the outer membrane and is typically a disaccharide of glucosamine that is both acylated and phosphorylated. The core and O-antigen carbohydrate domains are linked to the lipid A moiety through the eight-carbon sugar 3-deoxy-d-manno-octulosonic acid known as Kdo. Helicobacter pylori LPS has been characterized as having a single Kdo residue attached to lipid A, predicting in vivo a monofunctional Kdo transferase (WaaA). However, using an in vitro assay system we demonstrate that H. pylori WaaA is a bifunctional enzyme transferring two Kdo sugars to the tetra-acylated lipid A precursor lipid IVA. In the present work we report the discovery of a Kdo hydrolase in membranes of H. pylori capable of removing the outer Kdo sugar from Kdo2-lipid A. Enzymatic removal of the Kdo group was dependent upon prior removal of the 1-phosphate group from the lipid A domain, and mass spectrometric analysis of the reaction product confirmed the enzymatic removal of a single Kdo residue by the Kdo-trimming enzyme. This is the first characterization of a Kdo hydrolase involved in the modification of gram-negative bacterial LPS.

Download Full-text