Presence of Copper- and Zinc-Containing Superoxide Dismutase in Commensal
            <i>Haemophilus haemolyticus</i>
            Isolates Can Be Used as a Marker To Discriminate Them from Nontypeable
            <i>H. influenzae</i>
            Isolates

Fung, Wl; O'Dwyer, Clíona A.; Sinha, Sunita; Brauer, Aimee L.; Murphy, Timothy F.; Kroll, J. Simon; Langford, Paul R.

doi:10.1128/jcm.01376-06

Cited by 26 publications

(29 citation statements)

References 23 publications

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“…While previous studies have investigated H. influenzae pharyngeal colonization among healthy adults (4) and among individuals at risk for H. influenzae infections, such as children attending day care centers (8,14,56), patients with cystic fibrosis (49), and adults with COPD (38,43), no previous reports have documented colonization with H. haemolyticus in population-based studies of healthy adults. Pharyngeal colonization with nonhemolytic H. haemolyticus has only recently been described (16,39). The results of the present study describe the dynamics of H. influenzae and H. haemolyticus colonization over a 7-month period studied by culturing throat specimens from four healthy adult carriers at frequent intervals.…”

Section: Discussionmentioning

confidence: 84%

“…Isolates defined as H. haemolyticus were also NAD and hemin dependent but demonstrated clear hemolysis on horse blood agar (positive control, H. haemolyticus strain 11P31; negative control, H. influenzae type b strain Eagan), did not recognize the 7F3 epitope of P6, and lacked iga. Since H. haemolyticus isolates may lose hemolytic activity during subculture and NAD-and hemin-dependent, nonhemolytic isolates that lack the P6 epitope and iga are phylogenetically more related to H. haemolyticus (16,39), we designated such isolates nonhemolytic H. haemolyticus. The single nonhemolytic isolate that carried the 7F3 epitope of P6 but not the iga gene was designated a variant strain.…”

Section: Methodsmentioning

confidence: 99%

“…The hemolytic activity of H. haemolyticus, however, may be lost on subculture, resulting in difficulty differentiating it from H. influenzae. Since discriminating H. haemolyticus from H. influenzae is important to fully understand the pathogenesis of H. influenzae disease, in this study, the nonhemolytic isolates were further tested for the presence of a specific epitope on the outer membrane protein P6 and the presence of iga, both of which have been shown to be associated with H. influenzae and not H. haemolyticus (16,39).…”

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confidence: 99%

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Pharyngeal Colonization Dynamics of Haemophilus influenzae and Haemophilus haemolyticus in Healthy Adult Carriers

et al. 2007

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Haemophilus influenzae is an important cause of respiratory infections, including acute otitis media, sinusitis, and chronic bronchitis, which are preceded by asymptomatic H. influenzae colonization of the human pharynx. The aim of this study was to describe the dynamics of pharyngeal colonization by H. influenzae and an intimately related species, Haemophilus haemolyticus, in healthy adults. Throat specimens from four healthy adult carriers were screened for Haemophilus species; 860 isolates were identified as H. influenzae or H. haemolyticus based on the porphyrin test and on dependence on hemin and NAD for growth. Based on tests for hemolysis, for the presence of the 7F3 epitope of the P6 protein, and for the presence of iga in 412 of the isolates, 346 (84%) were H. influenzae, 47 (11%) were H. haemolyticus, 18 (4%) were nonhemolytic H. haemolyticus, and 1 was a variant strain. Carriers A and B were predominantly colonized with nontypeable H. influenzae, carrier C predominantly with b ؊ H. influenzae mutants, and carrier D with H. haemolyticus. A total of 358 H. influenzae and H. haemolyticus isolates were genotyped by pulsed-field gel electrophoresis (PFGE) following SmaI or EagI digestion of their DNA, and the carriers displayed the following: carrier A had 11 unique PFGE genotypes, carrier B had 15, carrier C had 7, and carrier D had 10. Thus, adult H. influenzae and H. haemolyticus carriers are colonized with multiple unique genotypes, the colonizing strains exhibit genetic diversity, and we observed day-to-day and week-to-week variability of the genotypes. These results appear to reflect both evolutionary processes that occur among H. influenzae isolates during asymptomatic pharyngeal carriage and sample-to-sample collection bias from a large, variable population of colonizing bacteria.Haemophilus species constitute approximately 10% of the total bacterial flora in the human upper respiratory tract (27). Haemophilus influenzae is an opportunistic pathogen in humans that asymptomatically colonizes the pharyngeal mucosa and occasionally the genital mucosa. The rate of carriage of H. influenzae increases from infancy (about 20% in the first year of life) to early childhood (Ͼ50% in children 5 to 6 years old), and H. influenzae is recoverable from the upper airways of 20 to 80% of healthy children (2,15,22,32).Colonization of the human respiratory mucosal surface represents a dynamic process in which bacteria are acquired, replaced, and reacquired many times in a lifetime. Past studies have demonstrated that H. influenzae colonization of the pharynx is characterized by rapid bacterial turnover (9, 12, 50, 58) and carriage of multiple strains at any one time (18,37,43,52,58). Previous studies have demonstrated a 62% week-to-week turnover rate of H. influenzae isolated from healthy children attending day care; 37 to 43% of throat cultures contained two or more genetically distinct strains (range, zero to five) (14,56).In addition to living as a commensal in the respiratory tract, H. influenzae may also cause s...

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Section: Discussionmentioning

confidence: 84%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Pharyngeal Colonization Dynamics of Haemophilus influenzae and Haemophilus haemolyticus in Healthy Adult Carriers

et al. 2007

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“…The Cu,Zn-superoxide dismutase gene sodC, which has been used as a marker of cryptic genospecies biotype IV (22) and H. haemolyticus (12), was detected with all variant strains and with only one strain of the Hi cluster (HK 2067 of serotype f) (Fig. 2).…”

Section: Vol 191 2009 Circumscription Of Haemophilus Influenzae 827mentioning

confidence: 99%

“…With respect to strain Rd (gene HI_0990), iga probes 1 to 4 cover nt 480 to 1959, 2063 to 3060, 3088 to 4344, and 4246 to ϩ26, respectively. hemN was amplified from strain CCUG 17210 by using primers hemN 219f and hemN 872r, and a sodC probe was amplified from H. parainfluenzae strain ATCC 29242 by using the primers from the work of Fung et al (12). DNA from the type strain of H. influenzae (HK 389 T ) was used as template in combination with the MLST primers (see above) to generate a fucK probe.…”

Section: Methodsmentioning

confidence: 99%

Delineation of the Species Haemophilus influenzae by Phenotype, Multilocus Sequence Phylogeny, and Detection of Marker Genes

2009

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To obtain more information on the much-debated definition of prokaryotic species, we investigated the borders of Haemophilus influenzae by comparative analysis of H. influenzae reference strains with closely related bacteria including strains assigned to Haemophilus haemolyticus, cryptic genospecies biotype IV, and the never formally validated species "Haemophilus intermedius". Multilocus sequence phylogeny based on six housekeeping genes separated a cluster encompassing the type and the reference strains of H. influenzae from 31 more distantly related strains. Comparison of 16S rRNA gene sequences supported this delineation but was obscured by a conspicuously high number of polymorphic sites in many of the strains that did not belong to the core group of H. influenzae strains. The division was corroborated by the differential presence of genes encoding H. influenzae adhesion and penetration protein, fuculokinase, and Cu,Zn-superoxide dismutase, whereas immunoglobulin A1 protease activity or the presence of the iga gene was of limited discriminatory value. The existence of porphyrin-synthesizing strains ("H. intermedius") closely related to H. influenzae was confirmed. Several chromosomally encoded hemin biosynthesis genes were identified, and sequence analysis showed these genes to represent an ancestral genotype rather than recent transfers from, e.g., Haemophilus parainfluenzae. Strains previously assigned to H. haemolyticus formed several separate lineages within a distinct but deeply branching cluster, intermingled with strains of "H. intermedius" and cryptic genospecies biotype IV. Although H. influenzae is phenotypically more homogenous than some other Haemophilus species, the genetic diversity and multicluster structure of strains traditionally associated with H. influenzae make it difficult to define the natural borders of that species.Bacterial diversity is usually expected to be organized into phenotypic and genetic clusters recognized as species. The diversity within species is thought to be confined by natural forces, although uncertainty exists as to the nature of the cohesion that constrains this diversity. There is increasing evidence that recombination occurs between distantly related bacteria and that barriers to this process, which could be used to define species naturally, are not always apparent (7, 11). As the bacterial species concept is central to taxonomy and evolutionary biology and has consequences for other disciplines such as the discrimination of pathogens from related bacteria with no pathogenic potential, there is a need to reevaluate to what extent accepted species are indeed coherent units.The gram-negative, nonmotile, facultatively anaerobic bacterium Haemophilus influenzae is a commensal organism of the pharynx frequently involved in localized infections of the respiratory tract, middle ear, and conjunctiva and sometimes in invasive infections such as meningitis or bacteremia. Presumptive identification is based on inability to synthesize NAD (V factor dependence) and porphyri...

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Haemophilus influenzae

Gilsdorf

2009

Bacterial Infections of Humans

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Presence of Copper- and Zinc-Containing Superoxide Dismutase in Commensal Haemophilus haemolyticus Isolates Can Be Used as a Marker To Discriminate Them from Nontypeable H. influenzae Isolates

Cited by 26 publications

References 23 publications

Pharyngeal Colonization Dynamics of Haemophilus influenzae and Haemophilus haemolyticus in Healthy Adult Carriers

Pharyngeal Colonization Dynamics of Haemophilus influenzae and Haemophilus haemolyticus in Healthy Adult Carriers

Delineation of the Species Haemophilus influenzae by Phenotype, Multilocus Sequence Phylogeny, and Detection of Marker Genes

Haemophilus influenzae

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