Table 1.JanFebMarAprMayJunJulAugSepOctNovDec# bb col/inf (2003)000101102001# bb col/inf (2004)002002102010# bb col/inf (2005)000014610110BACKGROUND/OBJECTIVES: The JGH has a 34-bed neonatal ICU with a history of infrequent pseudomonad infections, despite a large high-risk clientele. During the summer of 2005, we noted a sudden and pronounced increase in the number of babies colonized (col) and/or infected (inf) with Pseudomonas aeruginosa (Paer), Pseudomonas non-aeruginosa species (Pspe), and Stenotrophomonas maltophilia (Smal). METHODS: Epidemiologic investigation of the outbreak/cluster included: 1. monitoring the cultures of all babies; 2. extensive sampling of the NICU and case-room environment; 3. review of cleaning/disinfection procedures of all equipment;4. review of hand hygiene practices. RESULTS: The total number of col and/or inf NICU babies <b>per year</b> for the 2 years preceding the outbreak (i.e. 2003 and 2004) was 6 and 8, respectively. In 2005, there were 14 such infants, 10 of which were found during June and July alone. The number of new col and/or inf babies per month is seen in table 1. Extensive cultures revealed the absence of pseudomonads in all specimens except for the water tap "aerators" in many of the sinks of both the NICU and the Birthing Center. In collaboration with Technical Services (plumbers), a review of the installation & maintenance records of the 2 units showed that the faucets and aerators had been installed in 1992. More frequent (weekly) surface cleaning of the aerators had been instituted, with Environmental Services, in 2003. However, the aerators had never been changed. Visual inspection revealed large amounts of caked mineral deposit on the aerators. All aerators were changed between August 5-7, 2005. Only 2 babies have been found col/inf since the intervention. CONCLUSIONS: A sudden and dramatic increase in the number of neonates col and inf with pseudomonads was traced to environmental contamination of mineral-caked water faucet aerators in the NICU and the Birthing Center. Replacement of all aerators led to a rapid and sustained reduction in col and inf neonates. Contamination of water, faucets, and their accessories continue to play a role in NICU outbreaks with gram-negative organisms.