The Info List - Haemophilus

Not to be confused with Haemophilia


Haemophilus influenzae
Haemophilus influenzae
on a blood agar plate.

Scientific classification

Kingdom: Bacteria

Phylum: Proteobacteria

Class: Gammaproteobacteria

Order: Pasteurellales

Family: Pasteurellaceae

Genus: Haemophilus Winslow et al. 1917


H. aegyptius H. avium H. ducreyi H. felis H. haemoglobinophilus[1] H. haemolyticus H. influenzae H. parainfluenzae H. paracuniculus H. parahaemolyticus H. paraphrohaemolyticus[1] H. parasuis[1] H. pittmaniae H. piscium[1] H. segnis H. sputorum[1] H. somnus

is a genus of Gram-negative, pleomorphic, coccobacilli bacteria belonging to the Pasteurellaceae
family.[2][3] While Haemophilus
bacteria are typically small coccobacilli, they are categorized as pleomorphic bacteria because of the wide range of shapes they occasionally assume. These organisms inhabit the mucous membranes of the upper respiratory tract, mouth, vagina, and intestinal tract.[4] The genus includes commensal organisms along with some significant pathogenic species such as H. influenzae—a cause of sepsis and bacterial meningitis in young children—and H. ducreyi, the causative agent of chancroid. All members are either aerobic or facultatively anaerobic. This genus has been found to be part of the salivary microbiome.[5] Metabolism[edit] Members of the Haemophilus
genus will not grow on blood agar plates, as all species require at least one of these blood factors for growth: hemin (X-factor) and/or nicotinamide adenine dinucleotide (V-factor). They are unable to synthesize important parts of the cytochrome system needed for respiration, and they obtain these substances from the heme fraction, known as the X factor, of blood hemoglobin. The culture medium must also supply the cofactor nicotinamide adenine dinucleotide (from either NAD+ or NADP+), which is known as the V factor. Clinical laboratories use tests for the requirement of the X and V factors to identify the isolates as Haemophilus
species.<[4] Chocolate agar
Chocolate agar
is an excellent Haemophilus
growth medium, as it allows for increased accessibility to these factors.[6] Alternatively, Haemophilus
is sometimes cultured using the "Staph streak" technique: both Staphylococcus and Haemophilus
organisms are cultured together on a single blood agar plate. In this case, Haemophilus
colonies will frequently grow in small "satellite" colonies around the larger Staphylococcus colonies because the metabolism of Staphylococcus produces the necessary blood factor byproducts required for Haemophilus

Strain[7] Needs X-Factor Needs V-Factor Hemolysis on HB/Rabbit blood

H. aegyptius + + –

H. ducreyi + – –

H. influenzae + + –

H. haemolyticus + + +

H. parainfluenzae – + –

H. parahaemolyticus – + +


^ a b c d e LPSN bacterio.net ^ Holt JG, ed. (1994). Bergey's Manual of Determinative Bacteriology (9th ed.). Williams & Wilkins. ISBN 0-683-00603-7.  ^ Kuhnert P; Christensen H, eds. (2008). Pasteurellaceae: Biology, Genomics and Molecular Aspects. Caister Academic Press. ISBN 978-1-904455-34-9. [1].  ^ a b Tortora(1), Funke(2), Case(3), Gerard J(1), Berdell R(2), Christine L(3) (2016). Microbiology: An Introduction (12th ed.). Boston: Pearson. p. 301. ISBN 978-0321929150. OCLC 892055958. CS1 maint: Multiple names: authors list (link) ^ Wang, Kun; Lu, Wenxin; Tu, Qichao; Ge, Yichen; He, Jinzhi; Zhou, Yu; Gou, Yaping; Nostrand, Joy D Van; Qin, Yujia; Li, Jiyao; Zhou, Jizhong; Li, Yan; Xiao, Liying; Zhou, Xuedong (10 March 2016). "Preliminary analysis of salivary microbiome and their potential roles in oral lichen planus". Scientific Reports. 6 (1). doi:10.1038/srep22943. PMC 4785528 . PMID 26961389. Retrieved 6 May 2017.  ^ Ryan KJ; Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9.  ^ McPherson RA; Pincus MR, eds. (2011). Henry's Clinical Diagnosis and Management by Laboratory Methods (22nd ed.). Elsevier. ISBN 1437709745. 

External links[edit]

chapter in Baron's Medical Microbiology (online at the NCBI bookshelf). Raw Living Radio Interviews Dr Robert Cassar as part of a 3 Show Series in HD 2014 from the EarthShiftProject.com, an educational and informational research organization

Taxon identifiers

Wd: Q311275 EoL: 97482 EPPO: 1HAEPG GBIF: 3219815 ITIS: 957284 NCBI: 724 W