Comparison of Two Culture Media for Selective Isolation and Membrane Filter Enumeration of Pseudomonas aeruginosa in water

149 ABSTRACT. Pseudomonas aeruginosa is generally considered to be an ubiquitous bacteria of water and soils, nevertheless in recent years particular attention has been paid to this microorganism because of its increasing significance as a human pathogen and its high resistance to most antibiotics. Nowadays, there are a variety of methods for the detection of P. aeruginosa using different culture media. The aim of this work was to compare the recovery of P. aeruginosa and the selectivity of a synthetic and an undefined culture media (m-Acetamide and m-Cetrimide) by membrane filtration method. Diluted suspensions (10-6) of test bacterial cultures (ATCC collection) and simulated tap water samples (inoculated with highly diluted suspension of P. aeruginosa ATCC 27853) were analysed. The statistical analysis of simulated water samples data showed a significant difference (p < 0.05) in the enumeration of P. aeruginosa from water samples tested in m-Cetrimide and in m-Acetamide media, in favour of the latter. Overmore, m-Acetamide medium showed to be more selective and inhibitory for microorganisms other than P. aeruginosa. Sensitivity values were 96 and 100%, specificity values 95 and 100% and mean relative recovery frequency values 66.2 and 95.76 % for m-Cetrimide and m-Acetamide media, respectively. On the other hand, the advantage of m-Cetrimide medium was the faster growth of this microorganism.