ALA Disk

Rapidly differentiate Haemophilus species on the basis of the detection of porphyrin synthesis using Thermo Scientific™ Remel™ ALA Disk. In 1974, Kilian described a rapid method for identification of X-factor independent Haemophilus spp. based on the ability to synthesize heme precursors from ALA¹. Lund and Blazevic determined the porphyrin test is more rapid and accurate for identification of X-factor-independent strains of Haemophilus (e.g. H. parainfluenzae and H. parahaemolyticus) than the satellite test².

Members of the genus Haemophilus are small non-motile Gram-negative bacilli traditionally defined by a requirement for X and/or V factor³. X factor is derived from hemoglobin and V factor through the satellite relationship with Staphylococcus aureus.

Rapidly differentiate Haemophilus species on the basis of their detection of porphyrin synthesis using ALA Disk.

• Ready to use: Reagent-impregnated disk
• Rapid test: Results are obtained within a few hours.
• Accurate test: For detection of porphyrins which are only excreted by X-factor-independent Haemophilus spp.
• Easy to identify: A positive result showcases bright yellow fluorescence under long wave ultraviolet light.

After incubation the disk is exposed to long wave ultraviolet light in a dark room for any indication of fluorescence. Biberstein et al. studied the action of Haemophilus on δ-aminolevulinic acid (ALA) and reported a perfect correlation between X-factor-independence and the ability to convert ALA to porphyrins⁴.

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Remel™ and Oxoid™ products are now part of the Thermo Scientific brand.