A Taxonomic Study of the Genus Haemophilus, with the Proposal of a New Species

Abstract

A collection of 426 Haemophilus strains isolated from people with infectious diseases and from the normal flora of mucous membranes in humans and various animal species was studied in an attempt to revise and improve the taxonomy of the genus Haemophilus. The examinations included the determination of a number of biochemical and physiological properties, of which several had not previously been applied to the taxonomy of haemophili. The resulting data revealed many hitherto unrecognized characters of taxonomic significance, and several of the species can now be more accurately defined. The classification presented is supported by the DNA base composition of a large number of representative strains. A diagnostic key to the different taxa is presented. Haemophilus injluenzae and H. paruinfluenzae have been subdivided into a number of biotypes. It is possible to demonstrate a relationship between the individual biotypes of H. influenzae and the origin of the strains assigned to them. The results indicate that H. aegyptius, H. parahaemolyticus and H. paraphrohaemolyticus do not merit specific status. Four unnamed taxa of V-factor-dependent haemophili have been recognized. The name Haemophilus segnis is proposed for one of these taxa, which consists mainly of strains isolated from the human oral cavity. It is demonstrated that the name H. ducreyi has been used for different groups of bacteria, and that only one of these groups can legitimately be assigned to the genus Haemophilus. Haemolytic V-factor-dependent strains from swine, previously included in H. parahaemolyticus, are significantly different from strains of human origin and should be named H.pleuropneumoniae. None of the strains from swine and fowls were haemindependent. The relationships of these strains to the species H. suis and H. gallinarum, and to H. parasuis and H. paragallinarum are discussed. Haemophilus piscium is shown not to belong to the genus Haemophilus. The taxonomic position of H. aphrophilus is uncertain and its possible relationship to Actinobacillus actinomycetemcomitans requires further study. The positive correlation found between the ecology of the strains studied and their affiliation with the different taxa is discussed.

An analysis of the diversity ofHaemophilus parainfluenzaein the adult human respiratory tract by genomic DNA fingerprinting

“…The other species isolated were H. inftuenzae (2), H. parahaemolyticus (6), H. paraphrohaemolyticus (3) and H. segnis (1) depth by fingerprinting at least 25 colonies each from samples collected in March and July from subjects A and B. This revealed carriage of from 5-8 differentiable haemophilus strains from up to three different species, with the majority of isolates from each sample being H. parainfluenzae (Table 1).…”

“…Some species show a predeliction for particular anatomical sites, such as H. aphrophilus and H. segnis, whose normal habitat is the oral cavity [2,3]. Others are abundant only in certain age groups, H. influenzae for instance, being isolated much more frequently from healthy children than adults [4,5].…”

“…In infection, multiple types are rarely observed [15,16]. Typing schemes for H. parainfluenzae are not well developed and studies in healthy subjects have been limited to biotyping, eight types now being recognized [2,17].…”

Nasopharyngeal carriage and antibiotic resistance ofHaemophilus influenzaein healthy children

“…Organisms were accepted as H. infiuenzae if they were non-haemolytic on horse blood agar, exhibited satellitism around an XV disc and were unable to produce porphyrin from a substrate of aminolaevulinic acid (Kilian, 1976). Strains exhibiting iridescence on nutrient agar supplemented with 5% Filde's extract (Oxoid Ltd) were serotyped using agglutinating antisera from Wellcome Reagents Ltd.…”

Partial Analysis of the Genomes of Two Nontypeable Haemophilus influenzae Otitis Media Isolates

“…3B. Nearly all pathogenic isolates of H. influenzae test positive for indole production, one of the phenotypes used in the H. influenzae biotyping scheme (29). Tryptophanase catabolizes tryptophan to indole, pyruvate and ammonia, allowing tryptophan to be used as both a carbon and a nitrogen source (39).…”