Pseudomonas aeruginosa and the ICU Patient
The US National Nosocomial Infection Surveillance (NNIS) System reported that between 1992 and 1999, Pseudomonas, particularly P. aeruginosa, is among the most common agents of nosocomial infections in the United States. P. aeruginosa ranks second among the leading causes of nosocomial pneumonia and fourth among the causes of urinary tract infections. It has also been identified as one of the most frequent bloodstream isolates from critical care patients.
It's a common microorganism, thriving mostly in humid environments. It can be seen on land and in water, in plants and in animals, even humans. Although it is associated with infections of the external ear, P. aeruginosa doesn't do much harm in healthy individuals. The rate of carriage is also very low. But the rate of colonization and the risk of infection rise with the increase in seriousness of a patient's underlying disease and the decrease of immune status.
Several studies have pointed out that the presence of P. aeruginosa in the ICU setting can be traced to the use of certain tools and devices. For instance, P. aeruginosa-associated pneumonia in ICU patients usually results from the contamination of liquid reservoirs such as nebulizers in respiratory therapy equipment. Contamination doesn't happen only because of nonsterile handling of the equipment, although it is a big factor; in some instances, the backflow of contaminated liquids in the delivery tubes to the reservoir may introduce microorganisms and encourage their growth. And often, P. aeruginosa as well as other Gram-negative bacteria are capable of multiplying easily when introduced into certain environments-in the ICU, it doesn't have to reproduce large numbers of itself to bring about infection.
In the Philippines, pneumonia is the most prevalent nosocomial infection, many cases of which result from P. aeruginosa. In terms of ICU outbreaks, however, P. aeruginosa-related pneumonia happens fairly rarely.
In addition, the problem of antimicrobial resistance in the country is relatively less grave than in other countries, where conditions once prompted a World Health Organization official to warn that the world may have a decade or two left "to make use of many of the medicines presently available to stop infectious diseases." And according to the summary report of the NNIS (covering January 1992 to June 2002) published last year by the American Journal of Infection Control, in most antimicrobial-resistant bacteria, resistance rates are highest among ICU patients, followed by non-ICU inpatients, and then by outpatients. This only further emphasizes the importance of using antimicrobial agents rationally.
And more than anything else, this boils down to keeping the environment as well as the people and the equipment that go in and out as sterile as possible. It may sound simple, but it requires a lot of hard work and dedication to be done.
Jin Paul de Guzman
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