Pseudomonas aeruginosa outbreaks in the neonatal intensive care unit--a systematic review of risk factors and environmental sources.

Pseudomonas aeruginosa is a Gram-negative bacterium commonly occurring in soil and water. It is an opportunistic pathogen and an important cause of healthcare-associated infections, particularly among infants in neonatal intensive care units (NICUs). Several reports regarding outbreaks of P. aeruginosa in NICUs have been published. MEDLINE and EMBASE databases were searched using the MeSH terms [Pseudomonas aeruginosa], [Outbreak OR Infection OR bacteraemia, OR sepsis OR disease] and [Neonat* OR baby OR babies OR newborn*]. Fifteen studies describing a total of 414 infants colonized or infected with P. aeruginosa were reviewed. The mean percentage of infections occurring in the populations that had been colonized by the organism (calculated as n(infected)/n(infected)+n(colonized)) was 22%. Environmental sampling was performed in 14 studies, nine of which detected P. aeruginosa. The risk factors identified were antimicrobial drug use and the number of days of antimicrobial therapy prescribed before positive blood culture, exposure to particular healthcare workers (HCW), transfusion of blood products, and intravenous delivery of nutrients/electrolytes. Exposure to umbilical venous catheters was associated with bloodstream infections. Increasing age and use of artificial fingernails were risk factors for colonization of hands of HCWs. Low birth weight pre-term infants were at greater risk of mortality from P. aeruginosa infection than older infants.