These media provide a variety of enzymatic digests of proteinaceous substrates, inorganic salts and other nutrients to satisfy the nutritional requirements of these organisms. Selective agents are incorporated to improve the recovery of Burkholderia Cepacia by inhibiting common contaminants. PC agar incorporates crystal violet to inhibit gram-positive cocci, especially enterococci and staphylococci, bile salts to inhibit most gram-positive cocci other than enterococci, and ticarcillin and polymyxin B to inhibit gram-negative bacilli. OFPBL Agar incorporates polymyxin B to inhibit gram-negative flora, while bacitracin inhibits the gram-positive organisms and Neisseria. 4 PC Agar contains the pH indicator phenol red to facilitate detection of Burkholderia Cepacia. Alkaline end products from the metabolism of pyruvate raise the pH of the medium, causing the color of the indicator to change from light orange to pink or pink-red in the area of growth. In areas of heavy growth of Burkholderia Cepacia, the pink color intensifies. OFPBL Agar contains the pH indicator bromthymol blue to facilitate detection of Burkholderia Cepacia. Acid end products from the metabolism of lactose lower the pH of the medium resulting in a yellow color change. Burkholderia Cepacia colonies will also have a yellow color.

Gillian et al. developed PC Agar for improved recovery of Burkholderia Cepacia. 2 Crystal violet, bile salts and two antimicrobial agents are used as selective agents. Phenol red facilitates detection of Burkholderia Cepacia by a color change in the medium. They reported isolating Burkholderia Cepacia on PC Agar from respiratory secretions of 35 CF patients, but isolated the organism from only 21 patients on MacConkey Agar.2 Welch et al. developed a differential but less selective medium for the recovery of Burkholderia Cepacia. 4,5 This medium, OFPBL Agar, is OF (oxidation-fermentation) basal medium supplemented with polymyxin B, bacitracin, lactose and agar. The indicator, bromthymol blue, aids in the detection of Burkholderia Cepacia isolates through a color change in the medium. These investigators reported isolating Burkholderia Cepacia on OFPBL Agar from 58 CF patients, while only isolating this organism from 19 patients on MacConkey Agar.