Heterotrophic bacterial growth on hoses in a neonatal water distribution system.

After preliminary tests indicated an increased number of heterotrophic bacteria, we investigated possible sources of contamination in a neonatal intensive care unit (NICU) water distribution system. Scanning electron microscopic examination of flexible metallic hoses associated with the system revealed the presence of a biofilm; partial 16S rDNA sequencing revealed that the biofilm contained Blastomonas natatoria. Purgation of the water system three times a day, reinforced faucet cleaning, decreasing the cold water temperature to 12 degrees , and six repeated chlorinations at concentrations as high as 2 mg/L were not sufficient to eradicate the bacterial contamination. Replacing all of the rubber-interior flexible metallic hoses with teflon-lined hoses followed by heating the water to 70 degrees successfully controlled the bacteria.