PROTEOBACTERIA >> Gamma >> Haemophilus >> Haemophilus influenzae
HAEMOPHILUS INFLUENZAE
| Class: | Gamma Proteobacteria |
| Genus: | Haemophilus |
| Species: | Haemophilus influenzae |
| Description: | Gram negative, 0.3-0.5 / 0.5-3.0 μm ,rods or coccobacilli, nonmotile, but fresh clinical isolates express peritrichous pili with hemagglutinating properties which are lost after subcultivations. Fimbrial structures have been demonstrated in otitis media isolates of noncapsular strains. Many strains produce capsules.Colonies on chocolate agar are smooth, low, convex, grayish, translucent, 0.5-1.0 mm in diameter in 24 h. and 1-1.5 mm in 48h. Capsulated strains produce larger and more mucoid colonies (1-3 mm) with tendency to coalesce.On transparent agar media , colonies of capsulated strains show iridescence when examined under obliquely transmitted light. Morphologically atypical strains produce more granular colonies.Hemolysis is negative. Aerobic, facultatively anaerobic, require X-factor and V-factor for growth. CO2 is not required. Optimum temperature 35-37 ºC. Growth on Mac Conkey agar is negative. |
| Synonyms: | Influenza-bacillus Pfeiffer 1892, "Bacterium influenzae" Lehmann and Neumann 1896, "Mycobacterium influenzae" (Lehmann and Neumann 1896) Chester 1901, "Coccobacillus pfeifferi" Neveu-Lemaire 1921, "Haemophilus meningitidis" (Martins) Hauduroy et al. 1937. |
| Source: | This organism was first isolated in the 1890s during an influenza pandemic by Pfeiffer, and was originally thought to be the source of influenza, although later it was shown to be a secondary pathogen and may be synergistic with the influenza virus. |
| Pathogenicity: | This bacterium is one of the leading causes of meningitis in young children, and it may also cause septicemia, otitis media (inflammation of the middle ear), sinusitis (inflammation of the sinus cavity) and chronic bronchitis. It is highly adapted to its human host and typically lives in the nasopharynx and is a major cause of lower respiratory infections in infants and small children in developing countries (type 1b strain), although vaccine use has resulted in the decline of infections. The presence of the type B polysaccharide is important for virulence, as it is the most pathogenic of the 6 major types. The encapsulated organism can penetrate the blood and avoid both phagocytosis and complement-mediated lysis. All known strains produce neuraminidase and an IgA protease as well as fimbrial adhesins for attachment. |
| Genbank: | NC_000907.1 [Genome] [Nucleotide] |
| Size (Mb): | 1.83 |
| GC %: | 38.2 |
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| Reference: | Mogens Kilian, 2004.Genus III. Haemophilus. In: Bergey’s Manual of Systematic Bacteriology, Second edition,Vol two, part B,George M. Garrity (Editor-in-Chief), pp. 883-904,,Mary P.E. Slack, 2006.Haemophilus. In: Topley & Wilson’s Microbiology and Microbial Infections, 10 edition, Vol. 2,Bacteriology,Edward Arnold Ltd.,,G.Holt et al., 1994.Bergey’s manual of Determinative Bacteriology, 9-edition, Williams & Wilkins |
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