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BACTERIOLOGY
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GRAM
NEGATIVE
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FAMILIES
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| Acetobacteriaceae |
| Alcaligenaceae |
| Bacteroidaceae |
| Chromatiaceae |
| Enterobacteriaceae |
| Legionellaceae |
| Neisseriaceae |
| Nitrobacteriaceae |
| Pseudomonadaceae |
| Rhizobiaceae |
| Rickettsiaceae |
| Spirochaetaceae |
| Vibrionaceae |
| Genera of Unestablished Relationships |
| Brucella |
| Chromobacterium |
| Pseudomonas aeruginosa |
| CLASSIFICATION | VIRULENCE FACTORS | ENVIROMENTAL |
| BIOCHEMISTRY | NORMAL FLORA | INDUSTRIAL USES |
| GENETICS | PATHOGENS | VACCINES |
| SEROLOGY | LABORATORY ID |
Their classification is based on the production of a number of pigments including a pyocyanin (blue) and fluorescein (yellowish-green). Some strains also produce pyorubin (red), pyomelanin (brown), two other red pigments (aeruginosin A and B) and various other pigments. They are also sub-divided on the basis of serogroup and phage type. They have monotrichous flagellation.
Pseudomonas aeruginosa is strictly aerobic and oxidase and catalase positive. It can denitrify and produces gelatinase. It grows on acetamide and geraniol and gives a weak or delayed tween 80 hydrolysis. beta-haemolysis is produced on blood agar. Large amounts of extracellular polysaccharides are produced by some strains. Their optimal growth is at 37°C and they can grow at 42°C.
There are at least thirteen groups of plasmids based on compatibility. They carry markers conferring resistance to various antibiotics as well as chemicals like mercury and borate and tellurite and tellurate. There are also the so-called catabolic, plasmids carrying genes coding for the enzymes required in the breakdown of substances like naphthalene, salycylate and toluene. Some of these plasmids have a wide host range including most Gram-negative species. Genetic exchange between the chromosome and plasmids may occur.
Serogrouping is based on 12 somatic (O) antigen groups. Flagellar antigens are difficult to prepare and therefore not generally used for serogrouping.
Exotoxin A is produced under conditions of iron limitation by most strains. The toxin attacks one of the elongation factors in translation during protein synthesis which is thus inhibited.
Strains produce a haemolysin, causing beta-haemolysis.
The production of large amounts of extracellular polysaccharides is associated with strains isolated from cases of cystic fibrosis.
Endotoxin and exotoxin S are other virulence factors as are proteases and elastase.
It can be founds in many parts of the human body as well as animals. It can be found in soil and on plants. It is found in faeces, sewage, water, soil and air.
Infections:
Generally P. aeruginosa is considered an opportunistic pathogen. Under suitable conditions they can infect different types of wounds, particularly burns, but also the urinary and respiratory tracts. The organisms have been associated with pneumonia, endocarditis, meningitis and the strains producing large amounts of extracellular polysaccharides associated with cases of cystic fibrosis.
Strains of P. aeruginosa will not only grow at the usual temperature of 37°C used in clinical laboratories but at 28-30°C. It grows on most nurient media as flat greyish colonies with irregular edges. Isolates from the repiratory tract can be mucoid, particularly from cases of cystic fibrosis. The pigments are useful differentiating markers.
Can be found in water as well as environments in association with humans. They are often found in soil.
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