What is the Difference Between Pasteurella and Haemophilus?

Pasteurella and Haemophilus are two genera of the family Pasteurellaceae, which consists of gram-negative, rod-shaped, facultative anaerobic bacteria. Both genera have been reclassified in recent years, with some species being moved to different genera due to phylogenetic and phenotypic differences. Here are the main differences between Pasteurella and Haemophilus:

• Cell Surface Properties: Pasteurella species do not require chocolate agar or any other source for X and V factors, while some Haemophilus species do.
• Growth on Blood Agar: A number of Haemophilus species can grow sufficiently on most blood agar media, while some Pasteurella species do not.
• Species Reclassification: Due to phylogenetic and phenotypic differences, some species have been reclassified and moved to different genera. For example, Pasteurella multocida has been reclassified as Avibacterium gallinarum.
• Diagnostic Identification: No conclusive diagnostic identification is possible through selective culturing, phenotyping, or direct microscopic examination alone. Further differentiation between Pasteurella and Haemophilus species may be necessary.

Despite these differences, the distinction between Pasteurella and Haemophilus can be challenging, and further research is needed to better understand the relationships and differences between these genera.

Comparative Table: Pasteurella vs Haemophilus

Here is a table comparing the differences between Pasteurella and Haemophilus species:

Pasteurella species are primarily pathogens of cattle, sheep, fowl, and rabbits, while Haemophilus species are considered pathogens for humans. Pasteurella species often exhibit bipolar staining and are identified by biochemical and serologic methods. In contrast, Haemophilus species have a different colonial morphology compared to Pasteurella species. Both Pasteurella and Haemophilus species are facultative anaerobes that grow best on nutrient media enriched with blood, hematin, or catalase.