Pseudomonas aeruginosa
Pseudomonas aeruginosa
Pseudomonas aeruginosa (from Latin aerugo verdigris ) is a Gram-negative, rod oxidasepositives the genus Pseudomonas. It was discovered in 1900 by Walter Migula. The name refers to the blue - green color of pus in purulent infections. In 2000, the first time the complete genome of strain PAO1 was sequenced. The genome size of 6.3 Mbp and contains 5570 genes.
Occurrence
The bacterium is a widespread soil - and water-borne bacteria (wet seed ), which occurs in moist environment (in addition to moist soils and surface waters in tap water, sinks, showers, toilets, dishwashers, dialysis equipment, medicines and disinfectants ). Therefore, in the hygiene, it is considered an important germ hospital ( nosocomial germ ). But as a food spoiler, it plays a significant role, which is confirmed isolates from plants, fruits, food and the intestinal tract of humans and animals. It can even survive in distilled water or some disinfectants and grow if the smallest traces of organic substances are present.
Appearance
The stick can be 2-4 microns in size with tufted lophotriche flagella. Haftfimbrien allow the bacteria to stick to surfaces. On the outer cell membrane exopolysaccharide (alginate ) is superposed as a capsule. It protects against phagocytes and antibodies and counteracts the transport from the respiratory tract.
Metabolism
P. aeruginosa is not able to ferment ( fermenters ) and exists predominantly aerobic. Only in rare cases, it can switch to anaerobic lifestyle ( see Cystic fibrosis ). In various culture media (eg Cetrimide Agar ) recognizes dyes such as pyocyanin, pyoverdine, and Pyorubin Pyomelanin free. It is usually on agar "metallic - green " shiny. Characteristic is " linden like " sweet odor ( " gummy bear " smell ).
Recent research results indicate that P. aeruginosa with the help of the digestive enzyme sdsa even sodium lauryl sulfate ( SDS) can metabolize. Wherein the bacterium is able to survive even where other bacteria are killed due to the high concentration of SDS, for example, in shampoos.
P. aeruginosa produced under restricted growth conditions (eg, nitrogen, phosphate or iron limitation) on oils ( eg sunflower oil) from renewable resources called rhamnolipids. These are biosurfactants and some are already produced on an industrial scale and used as surfactants in detergents and cosmetics. Probably enter the cells into the surrounding them rhamnolipids from medium, to emulsify the oil, and to divide the oil into fatty acids and glyceride lipase means the water / oil interface. The Rhamnolipidsynthese is quorum sensing regulated is dependent on the cell density in the medium. In charge of this and the Las Rhl -regulated quorum sensing are.
Pathogenicity
The bacterium is a hospital bug, which has by its metabolism and its cell membrane structure of multiple resistance to antibiotics. With approximately 10 % of all hospital infections P. aeruginosa is one of the most common in Germany hospital germs. The spectrum of diseases caused by these bacteria is extensive. Trigger for this are, firstly, the ability to hemolysis and other virulence factors such as exotoxin A ( ADP- ribosyl ) and cytotoxins exoenzyme S and exoenzyme U, which the bacterium produces. The most common appearance are pneumonias in cystic fibrosis, which are particularly severe, especially in immunocompromised and AIDS patients. Urinary tract infections, enterocolitis, meningitis, otitis externa ( " swimmer 's ear " ) or infections on burn wounds can also be triggered.
Veterinary Medicine
The following are the most common veterinary findings are listed below:
- Inflammation of the external ear canal in dogs
- Suppuration and abscesses of the skin of many animal species
- Intestinal inflammation
- Mastitis in cows
- Vaginal infections, inflammation of the uterus and abortions in cows and mares
- Traumatic pericarditis in cattle
- General infection in poultry
- Ulcerated keratitis and conjunctivitis in horses
- Purulent necrotizing pneumonia
- Bleeding pneumonia in mink
- Buccal mucous membrane inflammations, abscesses and systemic infections in reptiles
Therapy
- β -lactam antibiotics (e.g., piperacillin ) aminoglycosides (gentamicin, tobramycin )
- Cephalosporins generation IIIb (higher activity against Pseudomonas spp. Than generation IIIa ) (eg, ceftazidime, cefepime )
- Gyrase inhibitors, such as ciprofloxacin or levofloxacin
- Carbapenems as a reserve antibiotic (eg, imipenem or meropenem )
Natural resistance to ampicillin sulbactam exist, amoxicillin clavulanic acid, most cephalosporins (especially all of the first and second generation), ertapenem, chloramphenicol, trimethoprim, tetracyclines and tigecycline. As a reserve antibiotic colistin is increasingly used.