Burkholderia Cepacia Medium | DM253D

Burkholderia Cepacia Medium | DM253D

A basal medium for the selective isolation of Burkholderia (Pseudomonas) cepacia

Recent studies have shown that B.cepacia is emerging as an increasingly important pulmonary pathogen.1-3 B.cepacia grows
slowly on commonly used laboratory media such as Blood Agar and MacConkey Agar and is often overgrown by organisms such as Pseudomonas .aeruginosa, Staphylococcus aureus and Escherichia coli, all commonly found in the respiratory tract of patients with cystic fibrosis. Relatively pure material uncontaminated by oral secretions is often difficult to obtain, resulting in the need for a selective medium specific for B.cepacia. Selective media for the isolation of B.cepacia have recently been investigated by a number of people. Wu and Thompson4 used 9- chloro-9-(4-diethylaminophenyl)-10 phenylacridan (C-390) and polymyxin B sulphate as selective agents, whereas Gilligan et al5 used polymyxin B as a selective agent but replaced C-390 with ticarcillin. MAST Burkholderia cepacia Medium is based on the formulation by Gilligan et al 5 to
enhance the recovery of B.cepacia from respiratory secretions. The medium contains a combination of bile salts and crystal violet as selective agents. However, it is designed for use with Burkholderia cepacia Selectatab™ and Selectavial™ (MS22, SV22) to give the required concentrations of ticarcillin and polymyxin B for the selective isolation of B.cepacia.

2. Technical Formula*

3. Directions
1. Suspend by swirling 32.5g of powder in 1 litre or the contents of the sachet in the stated volume of distilled or deionised water.
2. Ensure the medium is evenly suspended, boil to dissolve the agar and autoclave at 121ºC (15 p.s.i.) for 15 minutes.
3. Cool to 50-55ºC and hold in a water bath at this temperature.
4. The medium can be made selective by adding one B.cepacia Selectatab (MS22) per 100ml of medium, or one B.cepacia Selectavial (SV22) per 500ml.
5. Mix well and pour plates and allow to set.
6. Poured plates may be used immediately or stored at 4ºC for up to 2 weeks in plastic bags.

4. In Use

Burkholderia cepacia Medium supplemented with the appropriate antibiotics can be used to culture from respiratory secretions such as sputa, pharyngeal swabs or bronchial washings. For quantitative investigations inoculate additional plates with the prepared dilutions. Plates should be incubated and examined after 24 and 48 hours at 37C and then for a further 5 days at room temperature before being discarded. Colonies of B. cepacia will grow up to 1- 2mm in diameter, the medium often turning pink to purple especially in areas of heavy growth. Occasionally growth by some strains of Candida spp., Stenotrophomonas maltophilia, Comomonas acidovorans, multi-resistant Pseudomonas aeruginosa and Pseudomonas putida may occur on the medium but generally organisms other than B. cepacia will be strongly inhibited.