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Clinical Microbiology Reviews Jun 2021Haemophilus influenzae serotype b (Hib) was previously the most common cause of bacterial meningitis and an important etiologic agent of pneumonia in children aged... (Review)
Review
Haemophilus influenzae serotype b (Hib) was previously the most common cause of bacterial meningitis and an important etiologic agent of pneumonia in children aged <5 years. Its major virulence factor is the polyribosyl ribitol phosphate (PRP) polysaccharide capsule. In the 1980s, PRP-protein conjugate Hib vaccines were developed and are now included in almost all national immunization programs, achieving a sustained decline in invasive Hib infections. However, invasive Hib disease has not yet been eliminated in countries with low vaccine coverage, and sporadic outbreaks of Hib infection still occur occasionally in countries with high vaccine coverage. Over the past 2 decades, other capsulated serotypes have been recognized increasingly as causing invasive infections. H. influenzae serotype a (Hia) is now a major cause of invasive infection in Indigenous communities of North America, prompting a possible requirement for an Hia conjugate vaccine. H. influenzae serotypes e and f are now more common than serotype b in Europe. Significant year-to-year increases in nontypeable H. influenzae invasive infections have occurred in many regions of the world. Invasive H. influenzae infections are now seen predominantly in patients at the extremes of life and those with underlying comorbidities. This review provides a comprehensive and critical overview of the current global epidemiology of invasive H. influenzae infections in different geographic regions of the world. It discusses those now at risk of invasive Hib disease, describes the emergence of other severe invasive H. influenzae infections, and emphasizes the importance of long-term, comprehensive, clinical and microbiologic surveillance to monitor a vaccine's impact.
Topics: Child; Haemophilus Infections; Haemophilus Vaccines; Haemophilus influenzae type b; Humans; Infant; Serogroup; Vaccines, Conjugate
PubMed: 34076491
DOI: 10.1128/CMR.00028-21 -
British Medical Journal (Clinical... Oct 1984
Topics: Adult; Child; Child, Preschool; Haemophilus Infections; Haemophilus influenzae; Humans; Infant
PubMed: 6435732
DOI: 10.1136/bmj.289.6450.941 -
Schweizer Archiv Fur Tierheilkunde Oct 2017
Topics: Animals; Haemophilus Infections; Haemophilus parasuis; Real-Time Polymerase Chain Reaction; Swine; Swine Diseases; Switzerland
PubMed: 28952962
DOI: 10.17236/sat00131 -
Veterinary Research Oct 2015Haemophilus parasuis is an early colonizer of the porcine upper respiratory tract and is the etiological agent of Glasser's disease. The factors responsible for H.... (Review)
Review
Haemophilus parasuis is an early colonizer of the porcine upper respiratory tract and is the etiological agent of Glasser's disease. The factors responsible for H. parasuis colonization and systemic infection are not yet well understood, while prevention and control of Glasser's disease continues to be challenging. Recent studies on innate immunity to H. parasuis have demonstrated that porcine alveolar macrophages (PAMs) are able to differentially up-regulate several genes related to inflammation and phagocytosis, and several pro-inflammatory cytokines are produced by porcine cells upon exposure to H. parasuis. The susceptibility of H. parasuis strains to phagocytosis by PAMs and the bactericidal effect of complement are influenced by the virulent phenotype of the strains. While non-virulent strains are susceptible to phagocytosis and complement, virulent strains are resistant to both. However, in the presence of specific antibodies against H. parasuis, virulent strains become susceptible to phagocytosis. More information is still needed, though, in order to better understand the host immune responses to H. parasuis. Antimicrobials are commonly used in the swine industry to help treat and control Glasser's disease. Some of the common antimicrobials have been shown to reduce colonization by H. parasuis, which may have implications for disease dynamics, development of effective immune responses and immunomodulation. Here, we provide the current state of research on innate and adaptive immune responses to H. parasuis and discuss the potential effect of enrofloxacin on the development of a protective immune response against H. parasuis infection.
Topics: Adaptive Immunity; Animals; Anti-Bacterial Agents; Enrofloxacin; Fluoroquinolones; Haemophilus Infections; Haemophilus parasuis; Immunity, Innate; Swine; Swine Diseases
PubMed: 26511717
DOI: 10.1186/s13567-015-0263-3 -
Clinical Microbiology Reviews Jul 1989There are four currently recognized taxa to accommodate the avian haemophili: Haemophilus paragallinarum, Pasteurella avium, Pasteurella volantium, and Pasteurella... (Review)
Review
There are four currently recognized taxa to accommodate the avian haemophili: Haemophilus paragallinarum, Pasteurella avium, Pasteurella volantium, and Pasteurella species A (the last three being formerly united as Haemophilus avium). A range of other taxa has also been recognized, but they have been neither named nor assigned to a genus. All of these various taxa, legitimate and otherwise, have the common characteristic of requiring V factor, but not X factor, for in vitro growth. Several recent studies have established the phenotypic properties that allow the differentiation of the recognized taxa, both named and unnamed. The serological properties of H. paragallinarum, the causative agent of infectious coryza of chickens, has received considerable recent attention. In contrast, many questions on the pathogenicity and virulence mechanisms of H. paragallinarum remain unanswered. Another area requiring further work is the identification of those antigens responsible for inducing protective immunity in vaccinated or naturally infected chickens.
Topics: Animals; Birds; Haemophilus; Haemophilus Infections; Phenotype; Serologic Tests; Vaccination; Virulence
PubMed: 2670190
DOI: 10.1128/CMR.2.3.270 -
Nature Chemical Biology Jul 2023Bacterial capsules have critical roles in host-pathogen interactions. They provide a protective envelope against host recognition, leading to immune evasion and...
Bacterial capsules have critical roles in host-pathogen interactions. They provide a protective envelope against host recognition, leading to immune evasion and bacterial survival. Here we define the capsule biosynthesis pathway of Haemophilus influenzae serotype b (Hib), a Gram-negative bacterium that causes severe infections in infants and children. Reconstitution of this pathway enabled the fermentation-free production of Hib vaccine antigens starting from widely available precursors and detailed characterization of the enzymatic machinery. The X-ray crystal structure of the capsule polymerase Bcs3 reveals a multi-enzyme machine adopting a basket-like shape that creates a protected environment for the synthesis of the complex Hib polymer. This architecture is commonly exploited for surface glycan synthesis by both Gram-negative and Gram-positive pathogens. Supported by biochemical studies and comprehensive 2D nuclear magnetic resonance, our data explain how the ribofuranosyltransferase CriT, the phosphatase CrpP, the ribitol-phosphate transferase CroT and a polymer-binding domain function as a unique multi-enzyme assembly.
Topics: Infant; Child; Humans; Haemophilus influenzae type b; Haemophilus Infections; Haemophilus Vaccines; Bacterial Capsules; Gram-Negative Bacteria
PubMed: 37277468
DOI: 10.1038/s41589-023-01324-3 -
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 -
Respiratory Research Jul 2020Asthma is a complex heterogeneous disease. The neutrophilic subtypes of asthma are described as persistent, more severe and corticosteroid-resistant, with higher... (Review)
Review
Asthma is a complex heterogeneous disease. The neutrophilic subtypes of asthma are described as persistent, more severe and corticosteroid-resistant, with higher hospitalization and mortality rates, which seriously affect the lives of asthmatic patients. With the development of high-throughput sequencing technology, an increasing amount of evidence has shown that lower airway microbiome dysbiosis contributes to the exacerbation of asthma, especially neutrophilic asthma. Nontypeable Haemophilus influenzae is normally found in the upper respiratory tract of healthy adults and is one of the most common strains in the lower respiratory tract of neutrophilic asthma patients, in whom its presence is related to the occurrence of corticosteroid resistance. To understand the pathogenic mechanism by which nontypeable Haemophilus influenzae colonization leads to the progression of neutrophilic asthma, we reviewed the previous literature on nontypeable Haemophilus influenzae colonization and subsequent aggravation of neutrophilic asthma and corticosteroid resistance. We discussed nontypeable Haemophilus influenzae as a potential therapeutic target to prevent the progression of neutrophilic asthma.
Topics: Asthma; Haemophilus Infections; Haemophilus influenzae; Humans; Neutrophils
PubMed: 32620122
DOI: 10.1186/s12931-020-01438-5 -
Respiratory Research Mar 2022In chronic obstructive pulmonary disease (COPD), exacerbations cause acute inflammatory flare-ups and increase the risk for hospitalization and mortality. Exacerbations...
BACKGROUND
In chronic obstructive pulmonary disease (COPD), exacerbations cause acute inflammatory flare-ups and increase the risk for hospitalization and mortality. Exacerbations are common in all disease stages and are often caused by bacterial infections e.g., non-typeable Heamophilus influenzae (NTHi). Accumulating evidence also associates vitamin D deficiency with the severity of COPD and exacerbation frequency. However, it is still unclear whether vitamin D deficiency when combined with cigarette smoking would worsen and prolong exacerbations caused by repeated infections with the same bacterial strain.
METHODS
Vitamin D sufficient (VDS) and deficient (VDD) mice were exposed to nose-only cigarette smoke (CS) for 14 weeks and oropharyngeally instilled with NTHi at week 6, 10 and 14. Three days after the last instillation, mice were assessed for lung function, tissue remodeling, inflammation and immunity. The impact of VDD and CS on inflammatory cells and immunoglobulin (Ig) production was also assessed in non-infected animals while serum Ig production against NTHi and dsDNA was measured in COPD patients before and 1 year after supplementation with Vitamin D3.
RESULTS
VDD enhanced NTHi eradication, independently of CS and complete eradication was reflected by decreased anti-NTHi Ig's within the lung. In addition, VDD led to an increase in total lung capacity (TLC), lung compliance (Cchord), MMP12/TIMP1 ratio with a rise in serum Ig titers and anti-dsDNA Ig's. Interestingly, in non-infected animals, VDD exacerbated the CS-induced anti-NTHi Ig's, anti-dsDNA Ig's and inflammatory cells within the lung. In COPD patients, serum Ig production was not affected by vitamin D status but anti-NTHi IgG increased after vitamin D3 supplementation in patients who were Vitamin D insufficient before treatment.
CONCLUSION
During repeated infections, VDD facilitated NTHi eradication and resolution of local lung inflammation through production of anti-NTHi Ig, independently of CS whilst it also promoted autoantibodies. In COPD patients, vitamin D supplementation could be protective against NTHi infections in vitamin D insufficient patients. Future research is needed to decipher the determinants of dual effects of VDD on adaptive immunity.
TRAIL REGISTRATION
ClinicalTrials, NCT00666367. Registered 23 April 2008, https://www.clinicaltrials.gov/ct2/show/study/NCT00666367 .
Topics: Animals; Cigarette Smoking; Disease Models, Animal; Haemophilus Infections; Haemophilus influenzae; Lung; Male; Mice; Mice, Inbred C57BL; Pneumonia; Vitamin D Deficiency
PubMed: 35236342
DOI: 10.1186/s12931-022-01962-6 -
Veterinary Microbiology Mar 2020Antimicrobials have been commonly used to control bacterial diseases in farm animals. The efficacy of these drugs deterred the development of other control measures,... (Review)
Review
Antimicrobials have been commonly used to control bacterial diseases in farm animals. The efficacy of these drugs deterred the development of other control measures, such as vaccines, which are currently getting more attention due to the increased concern about antimicrobial resistance. Glässer's disease is caused by Glaesserella (Haemophilus) parasuis and affects pork production around the world. Balance between colonization and immunity seems to be essential in disease control. Reduction in antimicrobial use in veterinary medicine requires the implementation of preventive measures, based on alternative tools such as vaccination and other strategies to guarantee a beneficial microbial colonization of the animals. The present review summarizes and discusses the current knowledge on diagnosis and control of Glässer's disease, including prospects on alternatives to antimicrobials.
Topics: Animals; Anti-Bacterial Agents; Disease Management; Haemophilus Infections; Haemophilus parasuis; Microbiota; Nose; Swine; Swine Diseases; Vaccination
PubMed: 32122599
DOI: 10.1016/j.vetmic.2020.108595