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Veterinary bacteriology: information about important bacteria
Veterinary bacteriology

Species/Subspecies: Pseudomonas aeruginosa
Categories: Causes hemolysis; motile
Etymology: Genus name: false unit
Species epithet: full of copper rust (therefore green).
Significance:  [Very important]   
Type Strain: RH 815 = ATCC 10145 and 10145-U = CCUG 551, 28447 and 29297 = NCTC 10332.
Macromorphology (smell):
Large, flat and greenish colonies (2-4 mm in diameter) with irregular edges and typical metallic luster. The color is most visible on for instance TS-agar. Sometimes, a clear hemolysis zone is obtained on blood agar. Has distinctive smell (caramel, strawberry or raspberry soda). Some strains produce a green fluorescent pigment, pyoverdine. Some strains can also produce a blue pigment, pyocyanin.
Micromorphology: Small motile rod (0.5-0.8 x 1.5-3 µm) with a monotrichous flagellum.
Gram +/Gram -:
Metabolism: Is often classified as aerobic, but can also exploit NO3- as final electron acceptor in the respiratory chain. Should, therefore, be classified as facultatively anaerobic!
Other Enzymes: Tryptophanase -
Biochemical Tests: Citrate +, methyl red -, Voges-Proskauer -.
Fermentation of carbohydrates:
Lactose -
Spec. Char.: Temperature optimum: 37°C, but can also grow at 42°C.
P. aeruginosa has a capsule and can form biofilm a biofilm consisting of nucleic acids, amino acids and carbohydrates.
Reservoir: The environment: soil, water etc.
Disease:Mastitis, pneumonia, otitis, etc.
Hosts: Cattle, dog, horse, mink, poultry, sheep, reptiles etc. (including humans)
Clinical Picture:
Virulence Factors:

P. aeruginosa produces, in addition to LPS, also exotoxins. Exotoxin A is a so-called AB toxin, where the active part (A) is a ADP-ribosyltransferase, which modify EF2 (elongation factor 2) of the host cell, which in turn inhibits protein synthesis. Exoenzyme S also has ADP-ribosyltransferase activity, but act more unspecific on several of the host cell proteins. It is believed that the function is to knock out fagocytic cells to make way for the invasion of bacteria.

Pyocyanin is a toxic pigment, which induces oxidative stress in cells by generating H2O2 and superoxide radicals. Pyoverdine is a so-called siderophore, which forms a part of the bacterial iron metabolism.

P. aeruginosa has adhesins och invasins. May form a capsule and thrives in biofilms.

Genome Sequence:
Acc-noStrainSize (bp)Genome
NC_002516 PAO1 6 264 403 1c + 0 

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
Z76651 (T) 1491 

About 200 species have been described within genus Pseudomonas. Many of these species can be isolated from the environment and some of them are pathogenic. They are related to members within genus Moraxella and Acinetobacter. Many earlier described species within genus Pseudomonas have been transferred genus Burkholderia.
Comment:Opportunist, which can be isolated from the environment (soil and water). Resistant to many antibiotics. Produce the colour pigments pyocyanin and pyoverdine (see Virulence factors).
phage therpy has been used treat otitis caused by P. aeruginosa in humans.


The revised taxonomy of the mollicutes

The revised taxonomy of mollicutes (mycoplasmas) has now been introduced on VetBact, which means that many of the species have been given new genus names or moved to another higher taxon. 

Published 2021-11-25. Read more...

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