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Mogens Kilian - One of the best experts on this subject based on the ideXlab platform.

  • Diversity patterns of bacteriophages infecting Aggregatibacter and Haemophilus species across clades and niches
    The ISME Journal, 2019
    Co-Authors: Szymon P. Szafrański, Mogens Kilian, Ines Yang, Gesa Bei Der Wieden, Andreas Winkel, Jan Hegermann, Meike Stiesch
    Abstract:

    Aggregatibacter and Haemophilus species are relevant human commensals and opportunistic pathogens. Consequently, their bacteriophages may have significant impact on human microbial ecology and pathologies. Our aim was to reveal the prevalence and diversity of bacteriophages infecting Aggregatibacter and Haemophilus species that colonize the human body. Genome mining with comparative genomics, screening of clinical isolates, and profiling of metagenomes allowed characterization of 346 phages grouped in 52 clusters and 18 superclusters. Less than 10% of the identified phage clusters were represented by previously characterized phages. Prophage diversity patterns varied significantly for different phage types, host clades, and environmental niches. A more diverse phage community lysogenizes Haemophilus influenzae and Haemophilus parainfluenzae strains than Aggregatibacter actinomycetemcomitans and “ Haemophilus ducreyi” . Co-infections occurred more often in “H. ducreyi” . Phages from Aggregatibacter actinomycetemcomitans preferably lysogenized strains of specific serotype. Prophage patterns shared by subspecies clades of different bacterial species suggest similar ecoevolutionary drivers. Changes in frequencies of DNA uptake signal sequences and guanine–cytosine content reflect phage-host long-term coevolution. Aggregatibacter and Haemophilus phages were prevalent at multiple oral sites. Together, these findings should help exploring the ecoevolutionary forces shaping virus-host interactions in the human microbiome. Putative lytic phages, especially phiKZ-like, may provide new therapeutic options.

  • Identification of haemolytic Haemophilus species isolated from human clinical specimens and description of Haemophilus sputorum sp. nov
    International journal of medical microbiology : IJMM, 2012
    Co-Authors: Niels Nørskov-lauritsen, Brita Bruun, Camilla Andersen, Mogens Kilian
    Abstract:

    Haemolytic Haemophilus strains with no requirement for X factor are regularly isolated from sputum and throat swabs and occasionally from invasive infections, but the classification of such strains is not clear. We characterized 56 strains with a phenotype concordant with Haemophilus parahaemolyticus (V, but not X factor-dependent; urease-positive; tryptophanase-negative; ornithine decarboxylase-negative) by extended phenotypic testing and 16S rRNA gene sequencing. In addition, 31 of the strains and representative type strains were investigated by multilocus sequence analysis based on 3 housekeeping gene fragments. Most strains could be assigned to H. parahaemolyticus and were characterized by expression of IgA1 protease and a negative test for β-galactosidase. Isolation of H. parahaemolyticus from various infections and its absence among more than 300 commensal Haemophilus isolates suggests a pathogenic potential of this organism. The majority of haemolytic strains with β-galactosidase activity did not cluster with the type strain of H. paraphrohaemolyticus, but constituted a distinct and coherent novel taxon. Ten strains of this new taxon proved to be genetically and phenotypically homogeneous. Few biochemical characters discriminate the new taxon from related Haemophilus species, but identification is easily accomplished by routine matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Genetic, biochemical, and spectrometry data show that the taxon merits recognition as a novel species of Haemophilus. The name Haemophilus sputorum is proposed, with CCUG 13788(T) (=DSM 24472(T)=NCTC 13537(T)) as the type strain.

  • A RAPID METHOD FOR THE DIFFERENTIATION OF Haemophilus STRAINS.
    Acta pathologica et microbiologica Scandinavica. Section B: Microbiology and immunology, 2009
    Co-Authors: Mogens Kilian
    Abstract:

    A rapid and reliable test for demonstrating porphyrin synthesis in Haemophilus strains is described. The method is performed with cell suspensions, and tests the ability of the bacteria to use δ-aminolaevulinic acid in the biosynthesis of porphobilinogen and porphyrins. The method permits detection of some of the enzyme activities involved in the haemin biosynthetic pathway, and offers as such a more reproducible alternative to the traditional tests for haemin requirement in Haemophilus strains. The method described has been applied to 134 Haemophilus strains and the results applying to 45 strains from culture collections are listed.

  • reclassification of actinobacillus actinomycetemcomitans Haemophilus aphrophilus Haemophilus paraphrophilus and Haemophilus segnis as aggregatibacter actinomycetemcomitans gen nov comb nov aggregatibacter aphrophilus comb nov and aggregatibacter segn
    International Journal of Systematic and Evolutionary Microbiology, 2006
    Co-Authors: Niels Norskovlauritsen, Mogens Kilian
    Abstract:

    The aim of this study was to reinvestigate the relationships and the generic affiliations of the species Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Haemophilus paraphrophilus and Haemophilus segnis. The nicotinamide phosphoribosyltransferase gene (nadV) conferring V factor-independent growth was identified in Haemophilus aphrophilus. The gene encodes a polypeptide of 462 amino acids that shows 74.5 % amino acid sequence identity to the corresponding enzyme from Actinobacillus actinomycetemcomitans. Ten isolates of Haemophilus paraphrophilus all carried a nadV pseudogene. DNA from Haemophilus aphrophilus was able to transform Haemophilus paraphrophilus into the NAD-independent phenotype. The transformants carried a full-length nadV inserted in the former locus of the pseudogene. The DNA-DNA relatedness between the type strains of Haemophilus aphrophilus and Haemophilus paraphrophilus was 77 %. We conclude that the division into two species Haemophilus aphrophilus and Haemophilus paraphrophilus is not justified and that Haemophilus paraphrophilus should be considered a later heterotypic synonym of Haemophilus aphrophilus. Forty strains of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus and Haemophilus segnis were investigated by multilocus sequence analysis. The 40 strains form a monophyletic group clearly separate from other evolutionary lineages of the family Pasteurellaceae. We propose the transfer of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus and Haemophilus segnis to a new genus Aggregatibacter gen. nov. as Aggregatibacter actinomycetemcomitans comb. nov. (the type species; type strain ATCC 33384(T)=CCUG 13227(T)=CIP 52.106(T)=DSM 8324(T)=NCTC 9710(T)), Aggregatibacter aphrophilus comb. nov. (type strain ATCC 33389(T)=CCUG 3715(T)=CIP 70.73(T)=NCTC 5906(T)) and Aggregatibacter segnis comb. nov. (type strain HK316(T)=ATCC 33393(T)=CCUG 10787(T)=CCUG 12838(T)=CIP 103292(T)=NCTC 10977(T)). The species of the genus Aggregatibacter are independent of X factor and variably dependent on V factor for growth in vitro.

  • Multilocus sequence phylogenetic study of the genus Haemophilus with description of Haemophilus pittmaniae sp. nov.
    International Journal of Systematic and Evolutionary Microbiology, 2005
    Co-Authors: Niels Nørskov-lauritsen, Brita Bruun, Mogens Kilian
    Abstract:

    The phylogeny of human isolates of Haemophilus species was estimated based on partial sequences of four separate housekeeping genes. The clustering of each set of sequences was in accordance with speciation of the strains with few exceptions: of 108 gene fragments examined, only three appeared to have been subject to recombination events across the species barrier. Housekeeping gene similarity supported previous DNA–DNA hybridization data for the genus rather than the phylogeny inferred from 16S rRNA gene sequence comparison. The similarity of sequences of Haemophilus parainfluenzae with those of Haemophilus influenzae suggested preservation of the former species in the genus Haemophilus. Three strains representing a novel taxon were unique with respect to the four investigated gene loci. 16S rRNA gene sequence analysis suggested that this taxon belonged to the Parainfluenzae cluster. DNA–DNA hybridization data supported this generic placement. Nine strains of the novel taxon were available for analysis. They were distinct from representatives of all current species of the genus Haemophilus by conventional phenotypic characterization. Genotypic and phenotypic data show that the strains merit recognition as a novel species of Haemophilus. The name Haemophilus pittmaniae sp. nov. is proposed, with HK 85T (=CCUG 48703T=NCTC 13334T) as the type strain.

W. Albritton - One of the best experts on this subject based on the ideXlab platform.

  • Laboratory and clinical evaluations of media for the primary isolation of Haemophilus species.
    Journal of Clinical Microbiology, 1992
    Co-Authors: R Rennie, T Gordon, Y Yaschuk, P Tomlin, P Kibsey, W. Albritton
    Abstract:

    There has not previously been an objective comparison of medium formulations for the primary isolation of Haemophilus species. This study was undertaken to evaluate the components required for the optimal growth of large, easily identifiable colonies of these bacteria. We compared six medium bases and seven supplements for their ability to support the growth of 86 strains of Haemophilus influenzae and 17 strains of other species of Haemophilus. By using a growth index that combines colony size and the dilution factor, a formulation of GC agar base with 1% yeast autolysate and 5% sheep blood (chocolated) promoted the growth of large, easily recognizable colonies of H. influenzae and other Haemophilus species. This medium was designated GCYSB. The addition of hematin to supplements that supplied NAD (or factor V) to the medium was inhibitory to the growth of all of the Haemophilus species tested. In a clinical comparison of GCYSB with routinely used chocolate agar medium in two laboratories for the primary isolation of Haemophilus species, overall GCYSB promoted better growth of 124 strains of H. influenzae and H. parainfluenzae. GCYSB is easy to prepare and inexpensive compared with the ease of preparation and expense of other Haemophilus isolation media. Images

Niels Nørskov-lauritsen - One of the best experts on this subject based on the ideXlab platform.

  • Identification of haemolytic Haemophilus species isolated from human clinical specimens and description of Haemophilus sputorum sp. nov
    International journal of medical microbiology : IJMM, 2012
    Co-Authors: Niels Nørskov-lauritsen, Brita Bruun, Camilla Andersen, Mogens Kilian
    Abstract:

    Haemolytic Haemophilus strains with no requirement for X factor are regularly isolated from sputum and throat swabs and occasionally from invasive infections, but the classification of such strains is not clear. We characterized 56 strains with a phenotype concordant with Haemophilus parahaemolyticus (V, but not X factor-dependent; urease-positive; tryptophanase-negative; ornithine decarboxylase-negative) by extended phenotypic testing and 16S rRNA gene sequencing. In addition, 31 of the strains and representative type strains were investigated by multilocus sequence analysis based on 3 housekeeping gene fragments. Most strains could be assigned to H. parahaemolyticus and were characterized by expression of IgA1 protease and a negative test for β-galactosidase. Isolation of H. parahaemolyticus from various infections and its absence among more than 300 commensal Haemophilus isolates suggests a pathogenic potential of this organism. The majority of haemolytic strains with β-galactosidase activity did not cluster with the type strain of H. paraphrohaemolyticus, but constituted a distinct and coherent novel taxon. Ten strains of this new taxon proved to be genetically and phenotypically homogeneous. Few biochemical characters discriminate the new taxon from related Haemophilus species, but identification is easily accomplished by routine matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Genetic, biochemical, and spectrometry data show that the taxon merits recognition as a novel species of Haemophilus. The name Haemophilus sputorum is proposed, with CCUG 13788(T) (=DSM 24472(T)=NCTC 13537(T)) as the type strain.

  • Multilocus sequence phylogenetic study of the genus Haemophilus with description of Haemophilus pittmaniae sp. nov.
    International Journal of Systematic and Evolutionary Microbiology, 2005
    Co-Authors: Niels Nørskov-lauritsen, Brita Bruun, Mogens Kilian
    Abstract:

    The phylogeny of human isolates of Haemophilus species was estimated based on partial sequences of four separate housekeeping genes. The clustering of each set of sequences was in accordance with speciation of the strains with few exceptions: of 108 gene fragments examined, only three appeared to have been subject to recombination events across the species barrier. Housekeeping gene similarity supported previous DNA–DNA hybridization data for the genus rather than the phylogeny inferred from 16S rRNA gene sequence comparison. The similarity of sequences of Haemophilus parainfluenzae with those of Haemophilus influenzae suggested preservation of the former species in the genus Haemophilus. Three strains representing a novel taxon were unique with respect to the four investigated gene loci. 16S rRNA gene sequence analysis suggested that this taxon belonged to the Parainfluenzae cluster. DNA–DNA hybridization data supported this generic placement. Nine strains of the novel taxon were available for analysis. They were distinct from representatives of all current species of the genus Haemophilus by conventional phenotypic characterization. Genotypic and phenotypic data show that the strains merit recognition as a novel species of Haemophilus. The name Haemophilus pittmaniae sp. nov. is proposed, with HK 85T (=CCUG 48703T=NCTC 13334T) as the type strain.

Niels Norskovlauritsen - One of the best experts on this subject based on the ideXlab platform.

  • classification identification and clinical significance of Haemophilus and aggregatibacter species with host specificity for humans
    Clinical Microbiology Reviews, 2014
    Co-Authors: Niels Norskovlauritsen
    Abstract:

    SUMMARY The aim of this review is to provide a comprehensive update on the current classification and identification of Haemophilus and Aggregatibacter species with exclusive or predominant host specificity for humans. Haemophilus influenzae and some of the other Haemophilus species are commonly encountered in the clinical microbiology laboratory and demonstrate a wide range of pathogenicity, from life-threatening invasive disease to respiratory infections to a nonpathogenic, commensal lifestyle. New species of Haemophilus have been described (Haemophilus pittmaniae and Haemophilus sputorum), and the new genus Aggregatibacter was created to accommodate some former Haemophilus and Actinobacillus species (Aggregatibacter aphrophilus, Aggregatibacter segnis, and Aggregatibacter actinomycetemcomitans). Aggregatibacter species are now a dominant etiology of infective endocarditis caused by fastidious organisms (HACEK endocarditis), and A. aphrophilus has emerged as an important cause of brain abscesses. Correct identification of Haemophilus and Aggregatibacter species based on phenotypic characterization can be challenging. It has become clear that 15 to 20% of presumptive H. influenzae isolates from the respiratory tracts of healthy individuals do not belong to this species but represent nonhemolytic variants of Haemophilus haemolyticus. Due to the limited pathogenicity of H. haemolyticus, the proportion of misidentified strains may be lower in clinical samples, but even among invasive strains, a misidentification rate of 0.5 to 2% can be found. Several methods have been investigated for differentiation of H. influenzae from its less pathogenic relatives, but a simple method for reliable discrimination is not available. With the implementation of identification by matrix-assisted laser desorption ionization–time of flight mass spectrometry, the more rarely encountered species of Haemophilus and Aggregatibacter will increasingly be identified in clinical microbiology practice. However, identification of some strains will still be problematic, necessitating DNA sequencing of multiple housekeeping gene fragments or full-length 16S rRNA genes.

  • reclassification of actinobacillus actinomycetemcomitans Haemophilus aphrophilus Haemophilus paraphrophilus and Haemophilus segnis as aggregatibacter actinomycetemcomitans gen nov comb nov aggregatibacter aphrophilus comb nov and aggregatibacter segn
    International Journal of Systematic and Evolutionary Microbiology, 2006
    Co-Authors: Niels Norskovlauritsen, Mogens Kilian
    Abstract:

    The aim of this study was to reinvestigate the relationships and the generic affiliations of the species Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Haemophilus paraphrophilus and Haemophilus segnis. The nicotinamide phosphoribosyltransferase gene (nadV) conferring V factor-independent growth was identified in Haemophilus aphrophilus. The gene encodes a polypeptide of 462 amino acids that shows 74.5 % amino acid sequence identity to the corresponding enzyme from Actinobacillus actinomycetemcomitans. Ten isolates of Haemophilus paraphrophilus all carried a nadV pseudogene. DNA from Haemophilus aphrophilus was able to transform Haemophilus paraphrophilus into the NAD-independent phenotype. The transformants carried a full-length nadV inserted in the former locus of the pseudogene. The DNA-DNA relatedness between the type strains of Haemophilus aphrophilus and Haemophilus paraphrophilus was 77 %. We conclude that the division into two species Haemophilus aphrophilus and Haemophilus paraphrophilus is not justified and that Haemophilus paraphrophilus should be considered a later heterotypic synonym of Haemophilus aphrophilus. Forty strains of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus and Haemophilus segnis were investigated by multilocus sequence analysis. The 40 strains form a monophyletic group clearly separate from other evolutionary lineages of the family Pasteurellaceae. We propose the transfer of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus and Haemophilus segnis to a new genus Aggregatibacter gen. nov. as Aggregatibacter actinomycetemcomitans comb. nov. (the type species; type strain ATCC 33384(T)=CCUG 13227(T)=CIP 52.106(T)=DSM 8324(T)=NCTC 9710(T)), Aggregatibacter aphrophilus comb. nov. (type strain ATCC 33389(T)=CCUG 3715(T)=CIP 70.73(T)=NCTC 5906(T)) and Aggregatibacter segnis comb. nov. (type strain HK316(T)=ATCC 33393(T)=CCUG 10787(T)=CCUG 12838(T)=CIP 103292(T)=NCTC 10977(T)). The species of the genus Aggregatibacter are independent of X factor and variably dependent on V factor for growth in vitro.

R Rennie - One of the best experts on this subject based on the ideXlab platform.

  • Laboratory and clinical evaluations of media for the primary isolation of Haemophilus species.
    Journal of Clinical Microbiology, 1992
    Co-Authors: R Rennie, T Gordon, Y Yaschuk, P Tomlin, P Kibsey, W. Albritton
    Abstract:

    There has not previously been an objective comparison of medium formulations for the primary isolation of Haemophilus species. This study was undertaken to evaluate the components required for the optimal growth of large, easily identifiable colonies of these bacteria. We compared six medium bases and seven supplements for their ability to support the growth of 86 strains of Haemophilus influenzae and 17 strains of other species of Haemophilus. By using a growth index that combines colony size and the dilution factor, a formulation of GC agar base with 1% yeast autolysate and 5% sheep blood (chocolated) promoted the growth of large, easily recognizable colonies of H. influenzae and other Haemophilus species. This medium was designated GCYSB. The addition of hematin to supplements that supplied NAD (or factor V) to the medium was inhibitory to the growth of all of the Haemophilus species tested. In a clinical comparison of GCYSB with routinely used chocolate agar medium in two laboratories for the primary isolation of Haemophilus species, overall GCYSB promoted better growth of 124 strains of H. influenzae and H. parainfluenzae. GCYSB is easy to prepare and inexpensive compared with the ease of preparation and expense of other Haemophilus isolation media. Images