P. aeruginosa is a motile, Gram negative rods, facultative anaerobes bacteria that are non-spore forming and non-fermentative. It is a highly versatile bacterium that can utilise many different energy sources (2); hence it can grow readily on routine media including bile-containing selective media (3). Pseudomonas is distinctive in its ability to produce pigment, P. aeruginosa, in particular can be distinguished from other Pseudomonas by production of the blue-green pigment; pyocyanin.
Test HBA/O2 HBA/CO2 MAC/O2 Gram Oxidase Catalase King's A King's B
Growth Growth Lac -ve
-ve rods +ve +ve Blue pigment Yellow Pigment
Table 1: Results for 1st stage test and growth on HBA/O2, HBA/CO2, and MAC/O2
P. aeruginosa was identified on the basis of its Gram morphology (Gram -ve rod), inability to ferment lactose (lac-ve on MAC), a positive oxidase reaction and its distinctive fruity odour. To confirm P. aeruginosa, pigment production were enhance on special media (King's A and King's B). King's A media enhances pyocyanin production while King's B media enhances the production of the fluorescent pigment called pyoverdin. Fluorescence under ultraviolet light is helpful in early identification of P. aeruginosa colonies and may help identify its presence in wounds.