<p>Disease caused by the Gram-negative <italic>Haemophilus</italic> cryptic genospecies begins with colonization of the maternal genital or neonatal respiratory tract. The primary goal of this work was to identify and characterize the molecular determinant(s) of <italic>Haemophilus<i/talic> cryptic genospecies adherence as a means to better understand the specific adaptation of this species to the urogenital tract and neonatal respiratory tract. Using transposon mutagenesis of prototype strain 1595, we identified a locus that is essential for <italic>Haemophilus</italic> cryptic genospecies adherence to a variety of epithelial cell lines of both genital and respiratory origin. This locus encodes a protein called Cha that shares homology with trimeric autotransporters. Trimeric autotransporters are composed of an N-terminal signal peptide, an internal passenger domain that harbors adhesive activity, and a short C-terminal membrane anchor domain and are classically characterized by head-stalk-anchor domain architecture. By generating chimeric proteins, we demonstrated that the C-terminus of Cha trimerizes in the bacterial outer membrane and is capable presenting a heterologous passenger domain (Hia) in a functional form, thus confirming that Cha is a trimeric autotransporter. Southern analysis revealed that <italic>cha</italic> is unique to the <italic>Haemophilus</italic> cryptic genospecies and is ubiquitous among these strains. </p><p>Similar to a number of trimeric autotransporters, the passenger domain of Cha contains scattered clusters of YadA-like head domains associated with head-to-stalk neck adaptor motifs, predicted coiled-coil stalks and a series of identical tandem coding repeats which are not required for adherence. By evaluating the adherence capacity of <italic>H. influenzae</italic> expressing Cha deletion derivatives, we established that the N-terminal 473 residues of Cha harbor the binding domains responsible for Cha-mediated adherence to epithelial cells. In additional studies, we demonstrated that this same N-terminal region mediates bacterial aggregation through inter-bacterial Cha-Cha binding. </p><p>Further analysis revealed that variable Cha-mediated adherence is linked to spontaneous changes in the number of identical tandem repeats predicted to comprise a coiled-coil stalk domain. Variation in repeat copy number has a direct effect on Cha adhesive and aggregative activity, independent of an impact on transcription of the <italic>cha</italic> locus or surface localization of Cha protein. Moreover, length of Cha surface fibers correlates with repeat copy number expansion. We propose two hypotheses to explain how repeat expansion inhibits bacterial aggregation and host cell binding: 1) Variation in the number of 28-amino acid repeats may influence the conformation of Cha, thus changing the surface accessibility of the Cha binding pocket. 2) Repeat expansion results in the formation of long, flexible Cha fibers on the bacterial cell surface that may have a greater propensity to interact with neighboring Cha trimers at the N-terminus, thereby precluding adherence to other bacteria or host epithelial cells. </p><p>In additional studies screening adherent cryptic genospecies isolates for expression of Cha protein, we identified an additional, antigenically-divergent Cha variant that we refer to as Cha2. Amino acid sequence and domain comparison of Cha2 with Cha (now Cha1) revealed that the structurally undefined N-terminal sequences (encompassing the Cha1 adhesive and aggregative domain) are strikingly divergent. Inspite of this, Cha2 mediates efficient adherence to human epithelial cells, similar to Cha1.</p><p>Identification of Cha offers insight into the apparent tissue tropism associated with the <italic>Haemophilus</italic> cryptic genospecies. We speculate that the unique regulation of Cha adhesive activity enhances the adaptive capability of this pathogenic organism in the human host.</p> / Dissertation

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2009. / Härtill 5 uppsatser.

A Febre Purpúrica Brasileira - FPB- foi reconhecida como uma doença pediátrica fulminante, caracterizada por febre alta com rápida progressão para púrpura, choque e óbito. A grande maioria dos pacientes apresentaram conjuntivite prévia. O presente trabalho procura descrever os aspectos epidemiológicos desta doença, desde o surgimento dos primeiros casos, em 1984, em Promissão, Estado de São Paulo, Brasil. Foram registrados 277 casos distribuídos no Brasil em cinco Estados: São Paulo, Paraná, Mato Grosso, Mato Grosso do Sul e Minas Gerais. Fora do Brasil, dois casos foram relatados na Austrália. Cerca de 89% dos casos ocorreram em crianças de até cinco anos de idade. A letalidade foi de 38%. Estima-se o período de incubação médio de 15 dias. O quadro inicial se caracteriza por conjuntivite e febre. O agente etiológico é a bactéria Haemophilus influenzae biogrupo aegyptius, clone invasivo, tendo sido isolado de sangue, liquor, lesão hemorrágica de pele, secreção de conjuntiva e de orofaringe em 1986, de pacientes no Estado de São Paulo. Os estudos moleculares identificaram características diferentes das descritas até então para o Haemophilus aegyptius isolado de surtos de conjuntivite. Os principais surtos da doença ocorreram em Serrana, Valparaíso no Estado de São Paulo e Maracaju no Estado do Mato Grosso do Sul. Em algumas localidades com surtos de conjuntivite se observou a presença de moscas (Diptera). Acredita-se que estes insetos tenham participação na disseminação da doença. O diagnóstico precoce da FPB é um fator importante para redução da letalidade. / Brazilian Purpuric Fever- BPF- has been recognized as a fulminant pediatric disease characterized by fever with rapid progression to purpura, shock and death. The vast majority of BPF patients have previously presented conjunctivitis. The present work aims to describe epidemiological aspects of BPF since the appearance of the first cases, in 1984, in Promissão, State of São Paulo, Brazil. It has been reported 277 cases in Brazil, distributed by five states: São Paulo, Paraná, Mato Grosso, Mato Grosso do Sul and Minas Gerais. Outside Brazil, only two cases have been reported in Australia. About 89% from the total number of cases occurred in children aging five years old or less. The case fatality rate was 38%. The average incubation period is estimated as being 15 days. The initial clinical symptoms are conjunctivitis and fever. The etiologic agent of BPF is the bacteria Haemophilus influenzae biogroup aegyptius, invasive clone. It has been isolated from blood, cerebrospinal fluid, hemorrhagic skin lesion and conjunctival and orofarynx secretions in 1986, from São Paulo State patients. Molecular studies have identified different features from those described to H.aegyptius which have been isolated during conjunctivitis outbreaks since then. The most important BPF outbreaks occurred in Serrana and Valparaíso, State of São Paulo and in Maracaju, State of Mato Grosso do Sul. The presence of gnats (Diptera) has been observed in some of the places where conjunctivitis outbreaks have occurred. It is believed that these insects are associated with BPF transmission. Early diagnosis is an important factor in fatality reduction.

No description available.

This diploma thesis deals with the issue of the attitude of parents towards selected infectious diseases which are preventable by vaccines in the Czech Republic. The primary focus is on parents' opinions on vaccination against invasive diseases caused by meningococci, haemophili and pneumococci. The theoretical part discusses the issue of vaccination, its importance and organizational structure; it further describes the selected pathogens, the diseases they cause and the epidemiological situation. It also considers the factors that may lead many parents to distrust and be critical of vaccination. The main aim of the practical part is to find out by means of an online questionnaire which social, geo-demographic, economic and other factors influence the choice of parents to have their children vaccinated against the given bacteria. Statistical methods of χ2 -independence test and binary logistic regression have been used to evaluate the data obtained from the questionnaire with the help of the SPSS program. The results show that parents with lower education and fewer children are more likely to get their child vaccinated; furthermore, it is the parents in the vicinity of where the outbreak of the given disease occurred or those who obtain sufficient information from a pediatrician and consider this...

Nosocomial outbreaks of infection due to non-typeable Haemophilus influenzae (NTHi) are rarely described. There are a few published reports that suggest that elderly patients with underlying pulmonary disease are at risk and that person-to-person spread is key to disease transmission. During the summer months of 2005, we documented an outbreak of NTHi infections in a Veterans Affairs nursing home. Thirteen patients developed conjunctivitis or lower respiratory infection involving a β-lactamase-negative biotype III NTHi isolate, with an indistinguishable SmaI macrorestriction pattern. Patients were elderly males usually with underlying cardiac and pulmonary disease. A case-control study failed to demonstrate any specific significant risk factor for NTHi infection and there was no evidence of spatial clustering of cases within the nursing home. A random throat culture survey involving nursing home patients during the outbreak showed that only one of 19 persons was colonized with NTHi. The outbreak concluded following appropriate treatment and an emphasis on universal and respiratory droplet precautions. All patients recovered and a specific inciting event for the outbreak was never defined. Literature review revealed a spectrum of responses to nosocomial NTHi infections and a lack of consensus regarding the infection control approach towards NTHi outbreaks.

No description available.

No description available.

Virulent strains of the bovine opportunistic pathogen Haemophilus somnus (Histophilus somni) cause multi-systemic diseases in cattle. One of the reported virulence factors that H. somnus may use to persist in the host is resistance to intracellular killing. It is reported in this dissertation that H. somnus significantly (P <0.001) inhibited production of superoxide anion (O2-) by bovine mammary and alveolar macrophages as well as by polymorphonuclear leukocytes. Inhibition of O2- production was time- and dose-dependent and did not occur after incubation with Escherichia coli, H. influenzae, or Brucella abortus. Non-viable H. somnus, purified lipooligosaccharide (LOS), or cell-free supernatant from mid-log phase cultures did not inhibit O2- production, indicating that O2- inhibition required contact with live H. somnus. Commensal isolates of H. somnus were less capable or incapable of inhibiting macrophage O2- production compared to isolates tested from disease sites. H. somnus shares conserved epitopes in its LOS with Neisseria gonorrhoeae, N. meningitidis, and H. influenzae, and can also undergo structural phase variation of these LOS epitopes. Sialylation of the terminal galactose of H. somnus LOS is another reported virulence mechanism. Current sequencing of the genomes of H. somnus strains 2336 (pathogenic) and 129Pt (commensal) has enabled in silico identification of three open reading frames (ORFs) involved in sialylation. The ORFs-1 (hsst-I) and -2 (hsst-II) had BLASTx homology to sialyltransferases, while ORF-3 (neuAhs) had BLASTx homology to CMP-sialic acid synthetases. These ORFs were amplified by PCR and cloned into the expression vector pCWOri+. Thin layer chromatography of the hsst-I gene product showed this sialyltransferase exhibited preference for sialylation of terminal N-acetyllactosamine (LacNAc, beta-Gal-[1,4]-beta-GlcNAc-R). However, Hsst-II preferentially sialylated lacto-N-biose (LNB, beta-Gal-[1,3]-beta-GlcNAc-R). In this study, phase variation of the terminal linkage in isolate 738 from a 3 linked galactose (LNB) to a 4 linked galactose (LacNac) was demonstrated. Such variation of a glycose linkage appears to be a novel mechanism of LOS phase variation. Furthermore, the ability of sialylated strain 738 LOS vs de-sialylated strain 738 LOS to induce Toll-like receptor 4 signaling was decreased by 28%, as determined by ELISA for Macrophage Inflammatory Protein-2. Therefore, sialylated LOS may aid H. somnus to avoid host innate immunity. / Ph. D.