Background Nosocomial infections due to Pseudomonas aeruginosa have been well described, but the environmental reservoir of the organism varies. We conducted an epidemiologic and molecular investigation of endemic P. aeruginosa infection among infants in a neonatal intensive care unit that was associated with carriage of the organisms on the hands of health care workers. Methods In August 1998, colonization or infection with P. aeruginosa was identified in six infants. Surveillance cultures for P. aeruginosa were obtained from the other 27 infants in the unit, and possible environmental reservoirs were also assessed. The hands of health care workers were inspected and cultured, and risk factors for P. aeruginosa colonization were evaluated. Isolates were analyzed for clonality by pulsed-field gel electrophoresis. Results Surveillance cultures showed that three additional infants were colonized with P. aeruginosa. Cultures of environmental specimens were negative, but cultures of the hands of 10 of 165 health care workers (6 percent) were positive for P. aeruginosa. Increasing age (P=0.05) and a history of the use of artificial fingernails or nail wraps (P=0.03) were both risk factors for colonization of the hands. From January 1997 to August 1998, 49 infants were infected or colonized with P. aeruginosa. Pulsed-field gel electrophoresis demonstrated that 17 of these infants and I health care worker who had onychomycosis had the same clone. Infants who were exposed to this health care worker in August 1998 were at greater risk of having this clone than infants who were not exposed to this health care worker (odds ratio, 41.2; 95 percent confidence interval, 1.8 to 940.0; P=0.006). Conclusions An increased rate of infection and colonization with P. aeruginosa among infants in neonatal intensive care units should be investigated by assessing potential reservoirs, including environmental sources as well as patients and health care workers. (C) 2000, Massachusetts Medical Society.
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