15.1.3.4: Pseudomonas aeruginosa
- Page ID
- 42666
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This colorized version depicts a scanning electron micrograph (SEM) of a number of Pseudomonas aeruginosa bacteria. ("Pseudomonas aeruginosa" by Microbe World is licensed under CC BY-NC-SA 2.0)
Organism
- Pseudomonas aeruginosa is a Gram-negative rod motile by a polar flagellum
- Can respire using oxygen (aerobic) or nitrate (anaerobic) as the terminal electron acceptor
- Oxidase and catalase positive
- Produces blue/green pigments (Figure \(\PageIndex{1}\))
- Sometimes said to produce a fruity, grape-like smell
- Extermely metabolically versatile; able to use a wide array of carbon and energy sources
- Can grow in very low nutrient environments
- Highly antibiotic resistant (Figure \(\PageIndex{1}\))
Habitat
- P. aeruginosa can grow in almost any moist environment in temperatures from refrigeration to 42 degrees Celcius
- One reason for banning flowers in hospital units is their ability to harbor P. aeruginosa
- Bathing implements (such as loofahs, wash cloths, and brushes) can harbor P. aeruginosa if not allowed to dry completely between uses
- Because of tolerance of high temperatures, can surive in hot tubs
- Commonly found in soil and water and rarely in human intestinal flora (~3%)
- upon hospitalization, this can increase to ~20%
Source
- P. aeruginosa can enter the body from the environment in any number of ways, such as by inhalation or damaged skin
Epidemiology
- Opportunistic pathogen
- People with a weakened immune system, especially in health care facilities or with immune disorders such as AIDS, are at risk for severe P. aeruginosa infection
- Commonly associated with pneumonia and other respiratory infections in cystic fibrosis (CF) patients
- CF is a genetic disorder which causes mucus accumulation in the lungs
- CF patients cannot clear P. aeruginosa from their lungs, and there is some evidence that the mucus acts as a food supply for the P. aeruginosa
- Infection with P. aeruginosa can substantially decrease life expectancy for someone with CF; Life expectancy is already just 30-40 years (https://cmr.asm.org/content/32/3/e00138-18)
- Burn victims are also particularly susceptible to P. aeruginosa infection
- People without specific risk factors can also get infections, usually minor such as swimmer's ear or rash
Clinical Disease
- P. aeruginosa can infect alomost any tissue depending of the immune state of the patient and site of introduction
- Some of the most common serious infections are:
- Respiratory infections (particularly in CF patients)
- Bacteremia/septicemia
- Bone/joint infections
- Urinary tract infections
- Eye infections
- Some infections experienced by people without specific risk factors
- external otitis, including "swimmer's ear"
- predisposing conditions include injury, inflammation, or simply wet and humid conditions
- skin infections
- often located in moist areas of the body such as feet (particularly athletes, hikers, and military), perineal region, under diapers
- associated with hot tub use
- can be introduced into small abrasions during use of contaminated bathing implements (such as loofahs, wash cloths, and brushes)
- very common and serious in burn victims
- external otitis, including "swimmer's ear"
- P. aeruginosa can be very difficult to treat due to its extensive natural antibiotic resistance
Clinical Disease
- Biofilm formation: in most cases P. areuginosa is only virulent when living as a biofilm
- Polysaccharide capsule: prevents phagocytosis
- Pili for adherence
- Pyocyanin: pigment with toxicity to various types of cell
- Hemolysins (exotoxins which kill red blood cells) and leukocidins (exotoxins which kill white blood cells)
- Exoenzymes such as proteases (degrades proteins) and elastase (degrades elastin) allow P. areuginosa to invade tissues
- Like all Gram-negative bacteria, it has LPS/endotoxin
Additional Information: http://textbookofbacteriology.net/pseudomonas.html