Abstract
We analyzed an outbreak of gut colonization by Pseudomonas aeruginosa occurring in an intensive care hematology unit by using conventional typing methods and pulsed-field electrophoresis. In October and November 1989, the feces of four immunocompromised children undergoing total digestive decontamination were colonized by P. aeruginosa. Ten isolates were obtained from the gut flora in pure culture. Retrospective investigations found that one P. aeruginosa isolate from stools of one of the patients was already present at high counts 6 months before the outbreak. This patient had been discharged from the unit in May 1989 and had been readmitted concomitantly with the outbreak. Only pulsed-field electrophoresis could demonstrate that a single epidemic strain was present in the fecal flora of the children. This strain had probably been brought into the unit by the patient with chronic fecal carriage.