Haemophilus
Not to be confused with Haemophilia
| Haemophilus | |
|---|---|
 |
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| Haemophilus influenzae on a blood agar plate. | |
| Scientific classification | |
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| Phylum: | |
| Class: | |
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Haemophilus
Winslow et al. 1917
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| Species | |
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H. aegyptius |
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Haemophilus is a genus of Gram-negative, pleomorphic, coccobacilli bacteria belonging to the Pasteurellaceae family.[1][2] While Haemophilus bacteria are typically small coccobacilli, they are categorized as pleomorphic bacteria because of the wide range of shapes they occasionally assume. 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.
Metabolism
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 (factor X) and/or nicotinamide adenine dinucleotide (factor V). Chocolate agar is an excellent Haemophilus growth medium, as it allows for increased accessibility to these factors.[3] 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 growth.
| Strain[4] | Needs Factor X | Needs Factor V | Hemolysis on HB/Rabbit blood |
|---|---|---|---|
| H. aegyptius | + | + | - |
| H. ducreyi | + | - | - |
| H. influenzae | + | + | - |
| H. haemolyticus | + | + | + |
| H. parainfluenzae | - | + | - |
| H. parahaemolyticus | - | + | + |
References
External links
- Haemophilus 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 welcoming More participation from fellow Student Researchers, ...We want to Include More Student Researchers Including You!]
