Pseudomonas Aeruginosa
last authored: Feb 2010, David LaPierre
last reviewed:
Introduction
Pseudomonas is a uniquitous organism that only transiently colonizes health people. Serious opportunistic infections can occur during broad-spectrum antibiotic administration or in people with compromised immune systems
Pseudomonas is a common nosocomial agent, responsible for approximately 10% of hospital-acquired infections.
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
Epidemiology
Ubiquitous; found in soil, decaying matter, vegetation, water. They are often seen in rivers, lakes, swimming pools, and tap water.
Present in moist reservoirs in hospitals - mops, sinks, equiment, even disinfection solutions
Classification and Characteristics
Pseudomonas is a gram negative rod.
It is rich in genetic material, with almost as much as yeasts. This codes for a number of enzymes that allow for metabolism of various substrates.
Antimicrobial resistance is common and stems from its porins and the effective pump systems.
Many pseudomonads can grow at 4 C, and given their capacity to digest proteins and lipids, they are often responsible for spoiled food.
Transmission and Infection
Clinical Manifesations
Pseudomonas can transiently colonize the respiratory and gastrointestinal tracts.
Primarily opportunistic due to hosts' ability to prevent colonization and invasion. In compromised states, Pseudomonas can cause:
- urinary tract infections, particularly in patients with long-term indwelling catheters
- wound, burn infections
- abscess
- meningitis
- folliculitis or nail infections with frequent immersion in water
- pneumonia in patients with chronic lung conditions
Diagnosis
Frequent environmental contamination of samples leads to many false positives.
Isolation of pseudomonads in healthy people is of little concern.
Detection in hospitalized patients is more worrisome, but not much needs to be done unless there is clinical evidence of disease.
Treatment
Pseudomonas can be difficult to treat. It shows high rates of resistance to many antibiotics, including ceftriaxone and TMP/SMX. Options to consider, given local rates of resistance, include ciprofloaxacin (though guard against overuse), ceftazedime, pipercillin, gentamycin, tobramycin, and imipenem.
Resources and References
 |