P. aeruginosa are opportunistic pathogens as well as truepathogens. P. aeruginosa as true pathogen cause infections of the respiratory tract in patients with underlying disease of the respiratory tract. They also cause infection of urinary tract in patients with catheterization. P. aeruginosa as opportunistic pathogens causes most of human infections in immunocom-promised host. P. aeruginosa causes a wide variety of clinical syn-dromes as follows:
P. aeruginosa infection of the lower respiratory tract occursalmost exclusively in patients with malignancies and immuno-deficiencies. Primary nonbacteremic Pseudomonas pneumonia usually occurs in patients who have been colonized earlier with P. aeruginosa. This colonization is seen in patients with cysticfibrosis, other chronic disease, and in those with neutrope-nia. The condition manifests typically as a bilateral, diffuse bronchopneumonia often associated with pleural effusion. The condition is associated with a high mortality rate of 70%. The conditions that increase susceptibility of these patients to infection with P. aeruginosa include:
· Use of respiratory instruments during therapy, which may introduce these bacteria to the lower respiratory tract.
· Use of broad-spectrum antibiotics that inhibit normal microbial flora of the respiratory tract.
P. aeruginosa can cause a variety of skin infections, such asinfections of burn wound, chronic paronychia, infected toe web, pseudomonal folliculitis, and pseudomonal cellulitis. Infection of burn wounds is the most common recognized con-dition caused byP. aeruginosa. Pseudomonal wound infection is characterized by the presence of dark brown eschar associated with edema and hemorrhagic necrosis.
Pseudomonas skin infections are commonly seen in patientswho are exposed to moisture. Pseudomonal toe web infection is seen more commonly in children than in adults who are exposed to contaminated water in swimming pools, hot tubs, etc. P. aeruginosacauses paronychia (i.e., infection of the nail) in individuals whose hands are more exposed to water.
P. aeruginosa causes urinary tract infections in persons withindwelling urinary catheters and in persons undergoing instru-mentation and surgery of urinary tract. These infections usu-ally are hospital acquired and iatrogenic.
P. aeruginosa is one of the common agents causing external otitisin patients with history of swimming. The species is also respon-sible for causing malignant external otitis, a virulent form of dis-ease that occurs primarily in patients with diabetes or acquired immunodeficiency syndrome (AIDS) and in elderly patients.
P. aeruginosa causes pseudomonal endophthalmitis. The condi-tion may occur following trauma, intraocular surgery, or poste-rior perforation of corneal ulcer. Persons wearing contact lens are at increased risk of developing pseudomonal infection.
Cardiovascular infections, such as pseudomonal infectious endocarditis, are caused by involvement of both normal and abnormal valves (tricuspid, aortic, and mitral valve) on both sides of the heart. This condition leads to destruction of heart valves and subsequent heart failure. This condition is most commonly seen in patients who are intravenous drug abusers of pentazocine and triphenylamine.
Most infections caused by P. aeruginosa are opportunistic infec-tions seen in immunocompromised host. Such immunocom-promised hosts include:
Persons with dysfunctional immune mechanisms, such as those occurring in AIDS, cystic fibrosis, neonates, comple-ment deficiency, hypogammaglobulemia, and neutropenia.
Patients with injury to the skin and mucocutaneous mem-brane that occurs during burn injuries and during use of urinary catheters, dialysis catheters, endotracheal tubes, and intravenous lines.
P. aeruginosa causes bacteremia—a condition clinicallysimilar to Gram-negative bacteremia in immunocompromised patients. It also causes pseudomonal meningitis, which occurs in patients who are immunocompromised or have undergone neurosurgery.