Genetic Characterization of the Capsulation Locus of
            <i>Haemophilus influenzae</i>
            Serotype e

Giufrè, Maria; Cardines, Rita; Mastrantonio, Paola; Cerquetti, Marina

doi:10.1128/jcm.01721-09

Cited by 11 publications

(6 citation statements)

References 29 publications

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“…These data are not in agreement with a previous report using multilocus enzyme electrophoresis, in which encapsulated strains were divided into two major phylogenetic divisions, with Hie and most Hib strains belonging to the same division, division I, and Hif belonging to division II (26). On the other hand, Hie strains were previously found to share some features of Hif division II strains, such as the chromosomal location of the capsulation (cap) locus and the lack of association of the cap sequences with the IS1016 insertion element (27). Since some ncHi strains were also in clade A, we searched for their STs in the MLST database, but they were found to be associated only with ncHi strains and not with Hie or Hif strains, suggesting that if diversification from a common ancestor occurred, it was not a recent event.…”

Section: Discussionmentioning

confidence: 99%

Identification of Haemophilus influenzae Clones Associated with Invasive Disease a Decade after Introduction of H. influenzae Serotype b Vaccination in Italy

Giufrè

Cardines

Accogli

et al. 2013

Clin Vaccine Immunol

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The introduction of Haemophilus influenzae serotype b (Hib) conjugate vaccines has changed the epidemiology of invasive H. influenzae disease, with a shift in the predominant serotype from Hib to nonencapsulated H. influenzae (ncHi). The objective of this study was to identify the genotypes/clones associated with invasive H. influenzae disease in Italy. Eighty-seven H. influenzae strains isolated in the years 2009 to 2011 within the National Surveillance of Invasive Bacterial Disease program were analyzed. Strains were characterized by serotyping, antimicrobial susceptibility testing, and multilocus sequence typing (MLST). Genetic polymorphisms in the bla TEM gene promoter region as well as the occurrence of both adhesin genes (hmwA and hia) and the IgA1 protease-encoding gene (igaB) were also investigated. Of 87 strains, 67 were ncHi and 20 were encapsulated. Eleven strains were ␤-lactamase positive, harboring the bla TEM gene. Most bla TEM genes (10/11) were associated with a Pdel promoter region exhibiting a 135-bp deletion; the remaining strain possessed the Pa/Pb overlapping promoter. MLST analysis showed that encapsulated isolates were clonal, with each serotype sharing a few related sequence types (STs). Forty-six different STs were identified among the 67 ncHi strains. Despite this heterogeneity, a group of closely related STs (ST103, ST139, and ST145) encompassed almost 25% of all ncHi strains and 45.5% of the ␤-lactamase producers carrying the Pdel promoter. These major ST clones were found to be associated with the hmwA gene but not with the igaB gene. To conclude, although the heterogeneity of the ncHi population was confirmed, diffusion of major successful ST clones was documented.

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Section: Discussionmentioning

confidence: 99%

Identification of Haemophilus influenzae Clones Associated with Invasive Disease a Decade after Introduction of H. influenzae Serotype b Vaccination in Italy

Giufrè

Cardines

Accogli

et al. 2013

Clin Vaccine Immunol

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“…Region I genes (bexDCBA) code for an ATP-driven capsule export apparatus (53), while region III genes (hcsAB) are necessary for transport of polysaccharide across the outer membrane (54). Region II carries serotype-specific biosynthesis genes unique to each of the six capsule types; the regions from representatives of each serotype have been sequenced and comprise three to eight genes (49,(55)(56)(57)(58). Assignment to serotypes may be done by slide agglutination or by PCR; however, slide agglutination carries a high rate of discordance compared with PCR-based methods (59)(60)(61)(62)(63).…”

Section: The Haemophilus Influenzae Groupmentioning

confidence: 99%

Classification, Identification, and Clinical Significance of Haemophilus and Aggregatibacter Species with Host Specificity for Humans

2014

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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.

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“…Our objective was, therefore, to sequence the cap region II of Hie strain ATCC8142 and to deduce reliable PCR primers for Hie genotyping. During the course of manuscript preparation, the cap sequence of the Italian invasive Hie isolate 274, was published (Giufre et al, 2010) i.e. ecs1 through ecs8.…”

Section: Introductionmentioning

confidence: 99%

New diagnostic PCR for Haemophilus influenzae serotype e based on the cap locus of strain ATCC 8142

Lâm¹,

Elias²,

Frosch³

et al. 2011

International Journal of Medical Microbiology

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Genetic Characterization of the Capsulation Locus of Haemophilus influenzae Serotype e

Cited by 11 publications

References 29 publications

Identification of Haemophilus influenzae Clones Associated with Invasive Disease a Decade after Introduction of H. influenzae Serotype b Vaccination in Italy

Identification of Haemophilus influenzae Clones Associated with Invasive Disease a Decade after Introduction of H. influenzae Serotype b Vaccination in Italy

Classification, Identification, and Clinical Significance of Haemophilus and Aggregatibacter Species with Host Specificity for Humans

New diagnostic PCR for Haemophilus influenzae serotype e based on the cap locus of strain ATCC 8142

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