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

Detection of bacterial pathogens in Mongolia meningitis surveillance with a new real-time PCR assay to detect Haemophilus influenzae

“…Eight different Haemophilus spp. have been found to colonize the pharyngeal cavity of humans (Mukundan et al, 2007;McCrea et al, 2008), and the most prevalent are Hi and H. haemolyticus. H. haemolyticus is closely related to Hi both biochemically and phylogenetically.…”

Population-Level Virulence Factors Amongst Pathogenic Bacteria: Relation to Infection Outcome

“…If one is always purifying a single clone this is the same as having a blindfold on, because any diversity that is present will never be observed. Recently, the laboratories of Tim Murphy and Janet Gilsdorf have courageously demonstrated, by examining chronic obstructive pulmonary disease patients and the normal nasopharynx, respectively, that nearly all persons who are infected or colonized with H. influenzae are polyclonally infectedsometimes with more than 20 strains simultaneously [14,15,79]. Similarly, Dowson's group has observed polyclonal infection with pneumococcus [80], and the Hoiby and Molin groups in Denmark have observed polyclonal P. aeruginosa infections in the cystic fibrosis lung [81].…”

“…The distributed genome hypothesis states that for all species that have horizontal gene transfer (HGT) mechanisms there are extensive genic (as opposed to allelic) differences among the many strains of a species and that a species-level supragenome exists, therefore, that is much larger than the genome of any single strain [9][10][11][12][13]. This genomic plasticity combined with highly efficient inducible HGT mechanisms and polyclonal infections [14,15] provides a diversity generation mechanism that acts as a counterpoint to the host's adaptive immune response, providing for the evolution of new strains in response to stress [16].…”

Comparison of laboratory-based and phylogenetic methods to distinguish between Haemophilus influenzae and H. haemolyticus

“…Worse, it was reported recently that some strains of even low passage H. haemolyticus do not hemolyze, making this test unreliable (Murphy et al, 2007). In fact, between 4% and 27% of throat culture strains originally designated H. influenzae appear to be H. haemolyticus (Juliao et al, 2007, Mukundan et al, 2007, Murphy et al, 2007), a concern for research using throat strains. Because H. haemolyticus does not cause disease or live in normally sterile sites (Murphy et al, 2007, Xie et al, 2006), most clinical samples do not need to be tested for the presence of H. haemolyticus and may be tested for H. influenzae in the traditional manner, by X and V factor dependence (McCrea et al, 2008).…”