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Critical Reviews in Microbiology Mar 2021is the most common cause of bacterial infection in the lungs of chronic obstructive pulmonary disease (COPD) patients and contributes to episodes of acute exacerbation... (Review)
Review
is the most common cause of bacterial infection in the lungs of chronic obstructive pulmonary disease (COPD) patients and contributes to episodes of acute exacerbation which are associated with increased hospitalization and mortality. Due to the ability of to adhere to host epithelial cells, initial colonization of the lower airways can progress to a persistent infection and biofilm formation. This is characterized by changes in bacterial behaviour such as reduced cellular metabolism and the production of an obstructive extracellular matrix (ECM). Herein we discuss the multiple mechanisms by which contributes to the pathogenesis of COPD. In particular, mechanisms that facilitate bacterial adherence to host airway epithelial cells, biofilm formation, and microbial persistence through immune system evasion and antibiotic tolerance will be discussed.
Topics: Animals; Bacterial Adhesion; Haemophilus Infections; Haemophilus influenzae; Humans; Lung; Pulmonary Disease, Chronic Obstructive
PubMed: 33455514
DOI: 10.1080/1040841X.2020.1863330 -
Frontiers in Cellular and Infection... 2011Autotransporters are a large class of proteins that are found in the outer membrane of Gram-negative bacteria and are almost universally implicated in virulence. These... (Review)
Review
Autotransporters are a large class of proteins that are found in the outer membrane of Gram-negative bacteria and are almost universally implicated in virulence. These proteins consist of a C-terminal β-domain that is embedded in the outer membrane and an N-terminal domain that is exposed on the bacterial surface and is endowed with effector function. In this article, we review and compare the structural and functional characteristics of the Haemophilus influenzae IgA1 protease and Hap monomeric autotransporters and the H. influenzae Hia and Hsf trimeric autotransporters. All of these proteins play a role in colonization of the upper respiratory tract and in the pathogenesis of H. influenzae disease.
Topics: Adhesins, Bacterial; Bacterial Adhesion; Bacterial Outer Membrane Proteins; Haemophilus Infections; Haemophilus influenzae; Humans; Models, Molecular; Protein Structure, Quaternary; Protein Structure, Tertiary; Serine Endopeptidases; Virulence
PubMed: 22919571
DOI: 10.3389/fcimb.2011.00005 -
Frontiers in Cellular and Infection... 2012Haemophilus influenzae is a commensal of the human upper respiratory tract. H. influenzae can, however, move out of its commensal niche and cause multiple respiratory... (Review)
Review
Haemophilus influenzae is a commensal of the human upper respiratory tract. H. influenzae can, however, move out of its commensal niche and cause multiple respiratory tract diseases. Such diseases include otitis media in young children, as well as exacerbations of chronic obstructive pulmonary disease (COPD), sinusitis, conjunctivitis, and bronchitis. During the course of colonization and infection, H. influenzae must withstand oxidative stress generated by multiple reactive oxygen species produced endogenously, by other co-pathogens and by host cells. H. influenzae has, therefore, evolved multiple mechanisms that protect the cell against oxygen-generated stresses. In this review, we will describe these systems relative to the well-described systems in Escherichia coli. Moreover, we will compare how H. influenzae combats the effect of oxidative stress as a necessary phenotype for its roles as both a successful commensal and pathogen.
Topics: Haemophilus influenzae; Humans; Oxidative Stress; Reactive Oxygen Species; Stress, Physiological
PubMed: 22919631
DOI: 10.3389/fcimb.2012.00040 -
Future Microbiology Jun 2017To design a highly specific and sensitive multiplex real-time PCR assay for the differentiation of the pathogen Haemophilus influenzae from its nonpathogenic...
AIM
To design a highly specific and sensitive multiplex real-time PCR assay for the differentiation of the pathogen Haemophilus influenzae from its nonpathogenic near-neighbor Haemophilus haemolyticus.
MATERIALS & METHODS
A comparison of 380 Haemophilus spp. genomes was used to identify loci specific for each species. Novel PCR assays targeting H. haemolyticus (hypD) and H. influenzae (siaT) were designed.
RESULTS & DISCUSSION
PCR screening across 143 isolates demonstrated 100% specificity for hypD and siaT. These two assays were multiplexed with the recently described fucP assay for further differentiation among H. influenzae.
CONCLUSION
The triplex assay provides rapid, unambiguous, sensitive and highly specific genotyping results for the simultaneous detection of hypD and siaT, including fucose-positive H. influenzae (fucP), in a single PCR.
Topics: Bacterial Proteins; Genome, Bacterial; Genotype; Haemophilus; Haemophilus influenzae; Humans; Multiplex Polymerase Chain Reaction; Phylogeny; Proteins; Real-Time Polymerase Chain Reaction; Sensitivity and Specificity; Sequence Analysis, DNA
PubMed: 28604066
DOI: 10.2217/fmb-2016-0215 -
FEBS Letters Nov 2016Nontypeable Haemophilus influenzae (NTHi) is a commensal microbe often isolated from the upper and lower respiratory tract. This bacterial species can cause sinusitis,... (Review)
Review
Nontypeable Haemophilus influenzae (NTHi) is a commensal microbe often isolated from the upper and lower respiratory tract. This bacterial species can cause sinusitis, acute otitis media in preschool children, exacerbations in patients suffering from chronic obstructive pulmonary disease, as well as conjunctivitis and bacteremia. Since the introduction of a vaccine against H. influenzae serotype b in the 1990s, the burden of H. influenzae-related infections has been increasingly dominated by NTHi. Understanding the ability of NTHi to cause infection is currently an expanding area of study. NTHi is able to exert differential binding to the host tissue through the use of a broad range of adhesins. NTHi survival in the host is multifaceted, that is, using virulence factors involved in complement resistance, biofilm, modified immunoglobulin responses, and, finally, formation and utilization of host proteins as a secondary strategy of increasing the adhesive ability.
Topics: Adhesins, Bacterial; Bacterial Adhesion; Bacterial Typing Techniques; Biofilms; Haemophilus Infections; Haemophilus Vaccines; Haemophilus influenzae; Host-Pathogen Interactions; Humans; Immune Evasion; Virulence Factors
PubMed: 27508518
DOI: 10.1002/1873-3468.12351 -
Revista Chilena de Infectologia :... Dec 2013
Topics: Haemophilus influenzae
PubMed: 24522312
DOI: 10.4067/S0716-10182013000600015 -
Microbial Genomics Sep 2018Haemophilus influenzae, originally named Pfeiffer's bacillus after its discoverer Richard Pfeiffer in 1892, was a major risk for global health at the beginning of the... (Review)
Review
Haemophilus influenzae, originally named Pfeiffer's bacillus after its discoverer Richard Pfeiffer in 1892, was a major risk for global health at the beginning of the 20th century, causing childhood pneumonia and invasive disease as well as otitis media and other upper respiratory tract infections. The implementation of the Hib vaccine, targeting the major capsule type of H. influenzae, almost eradicated the disease in countries that adapted the vaccination scheme. However, a rising number of infections are caused by non-typeable H. influenzae (NTHi), which has no capsule and against which the vaccine therefore provides no protection, as well as other serotypes equally not recognised by the vaccine. The first line of treatment is ampicillin, but there is a steady rise in ampicillin resistance. This is both through acquired as well as intrinsic mechanisms, and is cause for serious concern and the need for more surveillance. There are also increasing reports of new modifications of the intrinsic ampicillin-resistance mechanism leading to resistance against cephalosporins and carbapenems, the last line of well-tolerated drugs, and ampicillin-resistant H. influenzae was included in the recently released priority list of antibiotic-resistant bacteria by the WHO. This review provides an overview of ampicillin resistance prevalence and mechanisms in the context of our current knowledge about population dynamics of H. influenzae.
Topics: Ampicillin; Anti-Bacterial Agents; Drug Resistance, Bacterial; Haemophilus influenzae; Microbial Interactions; Plasmids; beta-Lactams
PubMed: 30207515
DOI: 10.1099/mgen.0.000214 -
International Microbiology : the... Dec 2012The human respiratory tract contains a highly adapted microbiota including commensal and opportunistic pathogens. Noncapsulated or nontypable Haemophilus influenzae... (Review)
Review
The human respiratory tract contains a highly adapted microbiota including commensal and opportunistic pathogens. Noncapsulated or nontypable Haemophilus influenzae (NTHi) is a human-restricted member of the normal airway microbiota in healthy carriers and an opportunistic pathogen in immunocompromised individuals. The duality of NTHi as a colonizer and as a symptomatic infectious agent is closely related to its adaptation to the host, which in turn greatly relies on the genetic plasticity of the bacterium and is facilitated by its condition as a natural competent. The variable genotype of NTHi accounts for its heterogeneous gene expression and variable phenotype, leading to differential host-pathogen interplay among isolates. Here we review our current knowledge of NTHi diversity in terms of genotype, gene expression, antigenic variation, and the phenotypes associated with colonization and pathogenesis. The potential benefits of NTHi diversity studies discussed herein include the unraveling of pathogenicity clues, the generation of tools to predict virulence from genomic data, and the exploitation of a unique natural system for the continuous monitoring of long-term bacterial evolution in human airways exposed to noxious agents. Finally, we highlight the challenge of monitoring both the pathogen and the host in longitudinal studies, and of applying comparative genomics to clarify the meaning of the vast NTHi genetic diversity and its translation to virulence phenotypes.
Topics: Adaptation, Biological; Antigenic Variation; Gene Expression; Genetic Variation; Genotype; Haemophilus Infections; Haemophilus influenzae; Humans; Phenotype; Respiratory System; Respiratory Tract Infections; Virulence
PubMed: 23844475
DOI: 10.2436/20.1501.01.169 -
Microbiology (Reading, England) Apr 2010The Haemophilus influenzae ORF designated HI1275 in the Rd KW20 genomic sequence encodes a putative S-adenosyl methyltransferase with significant similarity to...
The Haemophilus influenzae ORF designated HI1275 in the Rd KW20 genomic sequence encodes a putative S-adenosyl methyltransferase with significant similarity to tellurite-resistance determinants (tehB) in other species. While the H. influenzae tehB can complement an Escherichia coli tehB mutation, thus restoring tellurite resistance, its role in H. influenzae is unknown. In a previous study defining the iron and haem modulon of H. influenzae, we showed that transcription of this gene in H. influenzae Rd KW20 increases during growth in iron- and haem-restricted media. Since iron and haem uptake genes, and other known virulence factors, constitute the majority of the iron- and haem-regulated gene set, we postulated that tehB may play a role in nutrient acquisition and/or the virulence of H. influenzae. A tehB mutant was constructed in the H. influenzae type b strain 10810 and was evaluated for growth defects in various supplemented media, as well as for its ability to cause infection in rat models of infection. Deletion of tehB leads to an increase in sensitivity both to tellurite and to the oxidizing agents cumene hydroperoxide, tert-butyl hydroperoxide and hydrogen peroxide. The tehB mutant additionally showed a significantly reduced ability to utilize free haem as well as several haem-containing moieties including haem-human serum albumin, haemoglobin and haemoglobin-haptoglobin. Examination of the regulation kinetics indicated that transcription of tehB was independent of both tellurite exposure and oxidative stress. Paired comparisons of the tehB mutant and the wild-type H. influenzae strain 10810 showed that tehB is required for wild-type levels of infection in rat models of H. influenzae invasive disease. To our knowledge this is the first report of a role for tehB in virulence in any bacterial species. These data demonstrate that H. influenzae tehB plays a role in both resistance to oxidative damage and haem uptake/utilization, protects H. influenzae from tellurite exposure, and is important for virulence of this organism in an animal model of invasive disease.
Topics: Animals; Bacterial Proteins; Gene Expression Regulation, Bacterial; Haemophilus Infections; Haemophilus influenzae; Heme; Humans; Oxidative Stress; Rats; Virulence
PubMed: 20075041
DOI: 10.1099/mic.0.036400-0 -
Frontiers in Cellular and Infection... 2012Nontypeable Haemophilus influenzae (NTHi) is an exclusive human pathogen, which has evolved a number of unique mechanisms to survive within the human environment. An... (Review)
Review
Nontypeable Haemophilus influenzae (NTHi) is an exclusive human pathogen, which has evolved a number of unique mechanisms to survive within the human environment. An important part of this is the ability of the organism to take up and incorporate sialic acid into its surface structures. This protects the organism against host adaptive and innate immune factor as well as serving as a mechanism for sustaining itself within biofilms. Recent evidence suggests that this also may be the source of the evolution of human antibodies to non-human sialic acid structures, which can lead to inflammation in the host. In very rare instances, evolution of antibodies to sialylated lipooligosaccharide (LOS) mimics of human antigens can result in autoimmune disease.
Topics: Autoimmune Diseases; Haemophilus Infections; Haemophilus influenzae; Humans; Immune Evasion; Sialic Acids
PubMed: 22919611
DOI: 10.3389/fcimb.2012.00019