To identify Haemophilus haemolyticus and Haemophilus parahaemolyticus, which plates should be used?

The identification of Haemophilus haemolyticus and Haemophilus parahaemolyticus requires specific growth conditions provided by particular culture media. The use of horse blood agar allows for the observation of hemolytic activity, which is essential for differentiating these organisms based on their hemolytic patterns.

Additionally, the inclusion of Mueller-Hinton agar with X and V strips facilitates the determination of the growth factor requirements of these bacteria. Haemophilus species typically require factor V (nicotinamide adenine dinucleotide, or NAD) and may also utilize factor X (heme). The use of strips containing these factors provides a way to confirm the ability of the organisms to utilize them for growth, which is critical for proper identification.

Chocolate agar is beneficial as it supports the growth of fastidious organisms like Haemophilus, but the choice of horse blood agar combined with the growth factor strips enhances the diagnostic accuracy in differentiating closely related species. Thus, this combination of media provides the appropriate environment and necessary factors for the successful identification of Haemophilus haemolyticus and Haemophilus parahaemolyticus.