Pseudomonas aeruginosa

Pseudomonas aeruginosa is a common bacterium that can cause disease in animals and humans. It can be found in soil, water, skin flora, and most man-made environments throughout the world. It thrives in normal or hypoxic atmospheres; due to this it has colonized many natural and artificial environments. It can infect animals with damaged tissue or people with reduced immunity.

Symptoms are generalized inflammation and sepsis. It can be fatal if colonization occurs in critical body organs, such as the lungs, the urinary tract, and kidneys, the results can be fatal. Since it can thrive on surfaces it is often found on and in medical equipment, including catheters, which can cause cross-infections in hospitals and clinics.

It’s a Gram-negative, aerobic, rod-shaped bacterium with unipolar motility. P. aeruginosa secretes a variety of pigments. It is often identified before hand by its pearlescent appearance and grape-like odor.

It is considered as a facultative anaerobe although it is classified as an aerobic organism. This organism can achieve anaerobic growth with nitrate as a terminal electron acceptor. Adaption to microaerobic or anaerobic environments is essential for certain lifestyles of P. aeruginosa.

Cell-surface polysaccharides play diverse roles in the bacterial lifestyle. They work as barriers between the cell wall and the environment, mediate host-pathogen interactions, and form structural components of biofilms. They polysaccharides are synthesized from nucleotide-activated precursors. In most cases all necessary enzymes are encoded by genes organized in dedicated clusters within the genome of the organism.

It is the most common infection of burn injuries and of the external ear. Pyocyanin is a virulence factor of the bacteria and has been known to cause death in C. elegans by oxidative stress. Salicylic acid can inhibit pyocyanin production. Cystic fibrosis patients are also predisposed to P. aeruginosa infection of the lungs. P. aeruginosa insudes symptoms in plants that include soft rot with Arabidopsis thaliana and Lactuca sativa.

Biofilms of Pseudomonas aeruginosa can cause chronic opportunistic infections. These infections can be a serious problem for medical care in industrialized societies, especially for immunocompromised patients and the elderly. Effective treatment is usually done with traditional antibiotic therapy. Depending on the nature of infection a specimen is sent to a bacteriology laboratory for identification. A gram stain is performed and if it is pure the organism is grown on MacConkey agar plate to produce colorless colonies.

It is frequently isolated from non-sterile sites and often represents colonization and not infection. Often no treatment is needed. When isolated from a sterile site it should be taken seriously and almost always requires treatment. It is naturally resistant to a large range of antibiotics and may demonstrate additional resistance after unsuccessful treatment through modification of a porin.
Most antibiotics must all be given by injection.