What is Pseudomonas aeruginosa?
Pseudomonas aeruginosa is a Gram negative bacteria that is
commonly found in the environment e.g. soil, water and other moist locations.
What diseases are caused by Pseudomonas aeruginosa?
Pseudomonas aeruginosa is an opportunistic pathogen. The
bacteria takes advantage of an individual's weakened immune system
to create an infection and this organism also produces
tissue-damaging toxins. Pseudomonas aeruginosa causes urinary tract
infections, respiratory system infections, dermatitis, soft tissue
infections, bacteremia, bone and joint infections, gastrointestinal
infections and a variety of systemic infections, particularly in
patients with severe burns and in cancer and AIDS patients who are
immunosuppressed.
Who is more susceptible to infection from Pseudomonas aeruginosa?
This bacterium is of particular concern to individuals with cystic fibrosis who are highly susceptible to pseudomonal lung infections. Pseudomonas aeruginosa is also of grave concern
to cancer and burn patients as well as those people who are
immunocompromised. The case fatality rate for individuals infected
with Pseudomonas aeruginosa approaches 50 percent.
Epidemiology of Pseudomonas aeruginosa
Pseudomonas aeruginosa is primarily a nosocomial pathogen.
According to the CDC, the overall incidence of P. aeruginosa
infections in US hospitals averages about 0.4 percent (4 per 1000
discharges), and the bacterium is the fourth most commonly-isolated
nosocomial pathogen accounting for 10.1 percent of all
hospital-acquired infections. Within the hospital, P. aeruginosa
finds numerous reservoirs: disinfectants, respiratory equipment,
food, sinks, taps, and mops. This organism is often reintroduced
into the hospital environment on fruits, plants, vegetables, as
well by visitors and patients transferred from other facilities.
Spread occurs from patient to patient on the hands of hospital
personnel, by direct patient contact with contaminated reservoirs,
and by the ingestion of contaminated foods and water.
Incubation Period
Usually 24-72 hours
Diagnosis of Pseudomonas aeruginosa
Diagnosis of P. aeruginosa infection depends upon isolation and
laboratory identification of the bacterium. It grows well on most
laboratory media and commonly is isolated on blood agar or eosin-methylthionine
blue agar. It is identified on the basis of its Gram morphology,
inability to ferment lactose, a positive oxidase reaction, its
fruity odor, and its ability to grow at 42° C. Fluorescence under
ultraviolet light is helpful in early identification of P.
aeruginosa colonies and may also help identify its presence in
wounds.
Treatment of Pseudomonas aeruginosa
Pseudomonas aeruginosa is frequently resistant to many commonly used antibiotics. Although many strains are susceptible to gentamicin, tobramycin, colistin, and amikacin, resistant forms have developed. The combination of gentamicin and carbenicillin is frequently used to treat severe Pseudomonas infections. Several types of vaccines are being tested, but none is currently available for general use.