Cetrimide Agar for Identification of Pseudomonas Aeruginosa, 500 g, Acumedia 7222A

Acumedia® Cetrimide Agar for Identification of Pseudomonas Aeruginosa, 500 g, 7222A

Features:

• Cetrimide Agar Base with 1.3% Agar is recommended as  selective medium for isolation of Pseudomonas aeruginosa similar in composition as cited in various pharmacopoeias except that concentration of agar in this medium is 1.3%
• Original formula was described by King et al 
• It can also be used for determining ability of organism to produce fluorescein and pyocyanain
• Cetrimide (N-acetyl-N-N,N-trimethylammaonium bromide) in  medium acts as selective agent inhibiting bacterias other than Pseudomonas aeruginosa
• It is quarternary ammonium salt, which acts as cationic detergent that reduces surface tension in point of contact and has precipitant, complexing and denaturing effects on bacterial membrane proteins
• It exhibits inhibitory actions on wide variety of microorganisms including Pseudomonas species other than Pseudomonas aeruginosa
• Magnesium chloride and potassium sulphate incorporated in medium enhances production of pigment pyocyanin, which is blue-green pigment, diffusing into medium which improves detection of Pseudomonas on this medium
• Presence of magnesium ions can also neutralize EDTA, if present in sample
• Gelatin peptone provides essential nutrients for growth of Pseudomonas, while glycerin/glycerol serves as slow and continuous carbon source for growing cell
• King et al developed Medium A for enhancement of pyocyanin production by Pseudomonas
• Cetrimide agar developed by Lowburry is modification of Tech Agar (Medium A) with addition of 0.1% cetrimide for selective isolation of P. aeruginosa
• Later, due to availability of highly purified cetrimide, its concentration in the medium was decreased
• Incubation was carried out at 37 degrees C for period of 18-24 hours
• P. aeruginosa can be identified due to their characteristic production of pyocyanin, a blue, water soluble, nonfluorescent phenazine pigment coupled with their colonial morphology and characteristic grape like odour of aminocetophenone
• For isolation of P. aeruginosa, plates of cetrimide agar should be inoculated from non-selective medium such as Brain Heart infusion Broth (M210) or Soyabean Casein Digest Medium (M011)
• If count is high, test sample can be directly inoculated onto Cetrimide Agar. P. aeruginosa colonies may appear blue, blue-green or nonpigmented
• Colonies exhibiting fluorescence 250 nm and blue green pigmentation are considered as presumptive positive
• P. aeruginosa may lose its fluorescence under UV if cultures are left at room temperature for short time
• Fluorescence reappears after plates are re-incubated
• Goto and Enomoto recommended that addition of nalidixic acid aids in inhibiting growth of accompanying flora
• Appearance: beige powder
• pH: 7 – 7.4
• Flammability (gas, solid): non-flammable
• Solubility: soluble in water