Microbial contamination of mist therapy units on six pediatric wards.

A study was conducted in six pediatric wards to investigated factors that influence microbial contamination of mist therapy units. Most samples from nebulizer reservoirs were positive for gram-negative bacilli which multiplied rapidly in distilled water and reached levels as high as 3.0 X 10(8) viable microorganisms per ml. High prevalence rates of Pseudomonas aeruginosa and coliform bacteria as well as high levels of gram-negative bacilli were found to be associated with infrequent and inadequate cleaning and disinfection of the nebulizing equipment. In one of the wards exhibiting high rates, a move to new quarters permitted the implementation of improved cleaning and maintenance procedures for mist therapy units. The result was a significant reduction of microbial contamination. This study reemphasizes the role of microbiological surveillance in assuring proper care of nebulizing equipment in the hospital.