Porphyrin Reagent

Determine the X factor (hemin) requirement for Haemophilus spp. using Thermo Scientific™ Remel™ Porphyrin Reagent. Biberstein et al. studied the action of Haemophilus strains with δ-aminolevulinic acid (ALA) and found a correlation between the absence of hemin requirement (X factor) and the ability to convert ALA to protoporphyrin¹. White and Granick found certain species of Haemophilus lack the enzyme to convert ALA to protoporphyrin, and are therefore X-dependent². Kilian developed a rapid test for demonstrating porphyrin synthesis using ALA as the substrate³.

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 tract⁵. The genus includes commensal organisms along with some significant pathogenic species such as H. influenzae—a cause of sepsis and bacterial meningitis in young children⁶.

The test for hemin requirement is a single substrate biochemical test. The substrate used is a combination of δ-aminolevulinic acid (ALA), a hemin precursor, and magnesium in a phosphate buffer. Hemin-independent Haemophilus spp. can utilize δ-aminolevulinic acid in the biosynthesis of hemin. Hemin-dependent Haemophilus spp. are enzymatically incapable of completing this biosynthesis and therefore, will not convert the ALA substrate^1-4.

• Ready-to-use – Liquid reagent
• Easy to interpret – Red-pink fluorescence indicates a positive test (Not X factor dependent) whereas no red-pink fluorescence indicates a negative test (X factor dependent)

This reagent contains 5-aminolevulinic acid and magnesium sulfate in a phosphate buffer and is supplied as 5mL vials.

Determination of X factor requirement is accomplished by detection of porphyrin synthesis from ALA as indicated by a red-pink fluorescence under long-wave (360 nm) ultraviolet light (Wood’s Lamp).

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