ABSTRACT
The genus Haemophilus is classiŠed in the family Pasteurellaceae, order Pasteurellales, class Gammaproteobacteria, phylum Proteobacteria. It encompasses a large group of gram-negative, aerobic or facultatively anaerobic, pleomorphic coccobacilli, forming many distinct species (e.g., H. aegyptius, H. avium, H. ducreyi, H. felis, H. haemolyticus, H. in§uenzae, H. parain§uenzae, H. paracuniculus, H. parahaemolyticus, H. pittmaniae, H. somnus, etc.).1-3
The compositions of the Haemophilus genus (haema, blood; philos, friend, loving; Haemophilus, blood-lover) have undergone signiŠcant changes in recent years, following the application of DNA-DNA hybridization, nucleotide sequencing, and other molecular procedures. It has been showed that H. aegyptius, H. parahaemolyticus, and H. paraphrohaemolyticus do not merit speciŠc status1; and H. aegyptius (causing conjunctivitis and Brazilian purpuric fever) is later proposed to be H. in§uenzae biogroup aegyptius.4,5 Hemolytic V-factor-dependent strains from swine, formerly in H. parahaemolyticus, demonstrate clear difference from strains of human origin and are designated H. pleuropneumoniae. Only one of the several groups that were once assigned to H. ducreyi remains within the species. Covering one of V-factor-dependent hemophili and consisting mainly of strains from the human oral cavity, H. segnis is now known as Aggregatibacter segnis.6 Similarly, Actinobacillus (Haemophilus) actinomycetemcomitans is reclassiŠed as
Aggregatibacter actinomycetemcomitans, and Haemophilus aphrophilus and Haemophilus paraphrophilus are combined to form a single species Aggregatibacter aphrophilus and emended an description of Aggregatibacter aphrophilus includes V-factor-dependent and V-factor-independent isolates.6 Haemophilus piscium is found to be distinct from the Haemophilus; H. suis and H. gallinarum as well as H. parasuis and H. paragallinarum from swine and fowls are not hemin-dependent.1,7,8 A novel species Haemophilus pittmaniae is established to cover several newly identiŠed isolates.9
