Colonization of intensive care unit patients by Pseudomonas aeruginosa.

Colonization and infection by Pseudomonas aeruginosa was found at several sites by selective culture in 32 of 66 patients in an intensive care unit. Twenty-four patients (75%) were colonized on admission, and eight patients (25%) acquired P. aeruginosa during hospitalization. Positive rectal cultures were more frequent than at any other site. The most common P. aeruginosa serotypes were 1, 2, 3 and 5, and pyocin types 1, 3, 5 and 10 were predominant. There were no significant differences in the serotypes or pyocin types detected on admission or acquired during hospitalization. The serotypes and pyocin types from the respiratory tract (trachea and nasopharynx) were different from those found in the rectum. Intubated patients were colonized more frequently than those not intubated and upper respiratory tract colonization correlated strongly with low initial arterial pH values.