Pseudomonas aeruginosa

[SKA]

anyone got any info on it?
is it hrad to grow on agar?
the differences between e.coli and staphylococcus aureus and Pseudomonas aeruginosa?
any info, links etc would be much appreciated

[Pigletion]

http://www.ncbi.nlm.nih.gov/sites/

Can search journals, books etc. The major resource used by scientists. Have fun

[jason.p]

Pseudomonas aeruginosa (used to be ps. pyocyanea as it turn pus blue) grows well on basic media and at room temp. Like E.coli ps aeruginosa is a gram negative rod(bacillus), whereas Stapylococci are gram positive cocci. It can be very resistant to antibiotics and disinfectants, in fact Cetavlon agar can be used to grow it selectively. It is easy to identify on agar plates as it has a bluish tinge and a sweet smell. To confirm identity it is strongly oxidase positive.

[jason.p]

Just remembered. Pseudomonas aeruginosa is a strict aerobe, and can be used as a control when using anaerobic growth conditions

[theprof]

I can provide you with info on P.aeruginosa and it's growth on agar, but I'm afraid that your third question is too broad in scope to answer on AB and you would be better off consulting a good textbook on bacteriology and comparing them yourself. I'm assuming that you're following the same course as you were the last time I replied on AB and with this in mind, I'm sure you'll agree that a few lines on AB would be insufficient for your needs.

Pseudomonas aeruginosa is a Gram-negative rod
(0.5-0.8 x 1.5-8 pm), which is mobile by polar flagella, and occurs singly, in pairs, or in short chains. This organism has a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor, although nitrate can be used as an alternate electron acceptor. The optimum growth temperature of P. aeruginosa is 37�C. Growth occurs at temperatures as high as 42"C, but not at 4�C. It does not require organic growth factors, and is able to multiply on a wide range of substrates.

In addition to its nutritional versatility, this organism is able to produce a wide variety of extracellular enzymes and an extensive slime layer, which can confer resistance to various antimicrobial agents. P. aeruginosa has a relatively large chromosome and it is known to harbour plasmids that can readily be exchanged. P. aeruginosa is generally considered to be an ubiquitous bacterium that is common in moist environments with low nutrient availability and low ionic strength.

(continued)

[theprof]

P. aeruginosa can be isolated from surface water, soil and vegetation, including vegetables and salads. Despite the presence of this bacterium in drinking water and on vegetables, it has rarely been associated with food-borne diseases. However, P. aeruginosa is a typical example of an opportunistic pathogen for humans; it does not attack normal healthy tissue, but can cause serious infection when tissue is damaged prior to exposure to virulent clones. Such clones, which constitute only a small percentage (1-2%) of environmental isolates, can synthesize extracellular products that are thought to play a role in its complex pathogenesis. These include a potent endotoxin or lipopolysaccharide, ADP-ribosyltransferase toxins (exotoxin A and exoenzyme S), haemolysins, phospholipase C (a haemolysin), cytotoxins, proteases,
including two with elastase activity, and adherence
factors (pili) In addition, the production of an alginate slime layer is a significant adaptation that protects P. aeruginosa against a wide range of environmental challenges.

(continued)

[theprof]

There is no standard detection method for P. aeruginosa.
Selective isolation media which contain components
to screen for this organism (such as cetrimide agar, King's agar, Pseudomonas CN agar, Pseudomonas
CFC agar) each have their own sensitivity and selectivity, and typical colonies on these media need to be confirmed by additional testing. The most distinguishing features of P. aeruginosa as compared with other Pseudomonas species are growth in the presence of nitrofurantoin and
growth at 42�C.

When high numbers of P. aeruginosa are present in foods, the organism can be detected by direct plating of food homogenates (tenfold serial dilutions in 0.1% peptone water) onto selective agar media. However, when cells are injured, or when only low numbers are present, direct plating may not be suitable.

For detection in water, the sample can be concentrated
by using hydrophobic grid membrane filters, and incubation of the membranes on selective agar medium (NF agar medium) A representative number of colonies from each filter need subsequent confirmation by further tests.

P. aeruginosa is oxidase positive; an oxidase reaction
can be performed using commercially available
oxidase strips