Capsule Gene Analysis of Invasive
            <i>Haemophilus influenzae</i>
            : Accuracy of Serotyping and Prevalence of IS
            <i>1016</i>
            among Nontypeable Isolates

Satola, Sarah W.; Collins, Julie T.; Napier, Ruth J.; Farley, Monica M.

doi:10.1128/jcm.00794-07

Cited by 53 publications

(57 citation statements)

References 56 publications

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“…Chromosomal DNA was extracted from 229 PCR-confirmed NTHI strains collected between August 1998 and December 2006 (9) and hybridized with digoxigenin-labeled pUO38 (39), pBR322 (8), or IS1016 as previously described (53).…”

Section: Methodsmentioning

confidence: 99%

“…In division I encapsulated H. influenzae strains, the cap locus is flanked by direct repeats of the IS1016 insertion element; division II encapsulated H. influenzae strains contain one or more IS1016 elements that are unassociated with cap genes. A number of investigators have shown that while IS1016 elements are generally absent in NTHI, they may be present in a small (but varying) proportion of NTHI isolates from the respiratory tract and invasive disease (53,59,60). It has been suggested that the presence of IS1016 in NTHI may be a marker for a more recent evolution from encapsulated H. influenzae (59,60).…”

mentioning

confidence: 99%

“…In this study, using a large, wellcharacterized isolate collection, we sought to identify additional IS1016-positive, invasive NTHI isolates and to compare the adhesin gene profiles, biotypes, and restriction patterns in IS1016-positive and IS1016-negative NTHI isolates to assess relatedness to each other and to patterns previously recognized among encapsulated strains. (53). The remaining 229 NTHI isolates collected from August 1998 through December 2006 were PCR capsule typed as previously described (53) with the following exception: new bexA primers were designed based on additional sequence information (bexA101-121, 5Ј-CAATTTTGAGYTAMAAAAAGG-3Ј; bexA646-627, 5Ј-TCCATRTCTTCAAAATGRTG-3Ј, where Y is C or T, M is A or C, and R is A or G).…”

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confidence: 99%

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Association of IS 1016 with the hia Adhesin Gene and Biotypes V and I in Invasive Nontypeable Haemophilus influenzae

2008

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A subset of invasive nontypeable Haemophilus influenzae (NTHI) strains has evidence of IS1016, an insertion element associated with division I H. influenzae capsule serotypes. We examined IS1016-positive invasive NTHI isolates collected as part of Active Bacterial Core Surveillance within the Georgia Emerging Infections Program for the presence or absence of hmw1 and hmw2 (two related adhesin genes that are common in NTHI but absent in encapsulated H. influenzae) and hia (homologue of hsf, an encapsulated H. influenzae adhesin gene). Isolates were serotyped using slide agglutination, confirmed as NTHI strains using PCR capsule typing, and biotyped. Two hundred twenty-nine invasive NTHI isolates collected between August 1998 and December 2006 were screened for IS1016; 22/229 (9.6%) were positive. Nineteen of 201 previously identified IS1016-positive invasive NTHI isolates collected between January 1989 and July 1998 were also examined. Forty-one IS1016-positive and 56 randomly selected IS1016-negative invasive NTHI strains were examined. The hia adhesin was present in 39 of 41 (95%) IS1016-positive NTHI strains and 1 of 56 (1.8%) IS1016-negative NTHI strains tested; hmw (hmw1, hmw2, or both) was present in 50 of 56 (89%) IS1016-negative NTHI isolates but in only 5 of 41 (12%; all hmw2) IS1016-positive NTHI isolates. IS1016-positive NTHI strains were more often biotype V (P < 0.001) or biotype I (P ‫؍‬ 0.04) than IS1016-negative NTHI strains, which were most often biotype II. Pulsed-field gel electrophoresis revealed the expected genetic diversity of NTHI with some clustering based on IS1016, hmw or hia, and biotypes. A significant association of IS1016 with biotypes V and I and the presence of hia adhesins was found among invasive NTHI. IS1016-positive NTHI strains may represent a unique subset of NTHI strains, with characteristics more closely resembling those of encapsulated H. influenzae.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Association of IS 1016 with the hia Adhesin Gene and Biotypes V and I in Invasive Nontypeable Haemophilus influenzae

2008

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“…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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“…Agglutination with antisera is an alternative method used for capsular typing. Even though this is a faster method than PCR, studies have shown that its accuracy is comparatively poor (12).…”

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confidence: 99%

Identification of Haemophilus influenzae Type b Isolates by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

et al. 2015

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dHaemophilus influenzae type b (Hib) is, in contrast to non-type b H. influenzae, associated with severe invasive disease, such as meningitis and epiglottitis, in small children. To date, accurate H. influenzae capsule typing requires PCR, a time-consuming and cumbersome method. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) provides rapid bacterial diagnostics and is increasingly used in clinical microbiology laboratories. Here, MALDI-TOF MS was evaluated as a novel approach to separate Hib from other H. influenzae. PCR-verified Hib and non-Hib reference isolates were selected based on genetic and spectral characteristics. Mass spectra of reference isolates were acquired and used to generate different classification algorithms for Hib/non-Hib differentiation using both ClinProTools and the MALDI Biotyper software. A test series of mass spectra from 33 Hib and 77 non-Hib isolates, all characterized by PCR, was used to evaluate the algorithms. Several algorithms yielded good results, but the two best were a ClinProTools model based on 22 separating peaks and subtyping main spectra (MSPs) using MALDI Biotyper. The ClinProTools model had a sensitivity of 100% and a specificity of 99%, and the results were 98% reproducible using a different MALDI-TOF MS instrument. The Biotyper subtyping MSPs had a sensitivity of 97%, a specificity of 100%, and 93% reproducibility. Our results suggest that it is possible to use MALDI-TOF MS to differentiate Hib from other H. influenzae. This is a promising method for rapidly identifying Hib in unvaccinated populations and for the screening and surveillance of Hib carriage in vaccinated populations. Haemophilus influenzae type b (Hib) has been, and in some regions still is, the dominating cause of severe invasive disease associated with the species H. influenzae. More specifically, it is (or used to be) a feared cause of meningitis and epiglottitis in small children (1, 2). The conjugate vaccines against Hib that were introduced in the early 1990s have resulted in a steep decline in invasive Hib disease (1, 3-5). However, Hib still causes 5 to 10% of invasive H. influenzae disease in Sweden, and occasional cases of fully vaccinated children with invasive Hib disease have been reported in several countries (6, 7). Hib is estimated to cause a substantial number of infections and deaths among young children each year on a global basis (8). PCR is at present required for accurate Hib capsule typing (9-11) but is a relatively time-consuming and laborious method. Agglutination with antisera is an alternative method used for capsular typing. Even though this is a faster method than PCR, studies have shown that its accuracy is comparatively poor (12).Early studies have suggested that the Hib population consists of two genetically distinct clusters (13,14). This population structure was later confirmed using multilocus sequence typing (MLST), since practically all Hib isolates that had been submitted to the MLST database from all over the world cou...

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Capsule Gene Analysis of Invasive Haemophilus influenzae : Accuracy of Serotyping and Prevalence of IS 1016 among Nontypeable Isolates

Cited by 53 publications

References 56 publications

Association of IS 1016 with the hia Adhesin Gene and Biotypes V and I in Invasive Nontypeable Haemophilus influenzae

Association of IS 1016 with the hia Adhesin Gene and Biotypes V and I in Invasive Nontypeable Haemophilus influenzae

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

Identification of Haemophilus influenzae Type b Isolates by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

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