Low level of bacterial contamination of mist tents used in home treatment of cystic fibrosis patients

Abstract

Mist tents are recommended by the Stockholm cystic fibrosis (CF) centre for small children with CF. Daily disinfection of some parts of the tent with 2% acetic acid is recommended, and for other parts boiling water followed by air-drying without rinsing. The plastic tent is discarded each day. We have studied whether these prescribed routines are followed by the patients and whether they are sufficient to prevent bacterial contamination. The mist tent equipment of 20 CF patients (mean age 7 years, range 1-15 years), two of whom were chronically colonized with Pseudomonas aeruginosa, were investigated. All patients were visited at home in the morning after 6-12 hours aerosol therapy. Liquid from the nebulizing chambers and swabs from the aerosol tube were examined by culture on four different media. Seventeen of 20 patients claimed that they cleaned and disinfected the tubes every day, two patients every other day and one once a week. Seventeen of 19 claimed they cleaned and disinfected the chambers daily, one once a week and, one twice a week. No or insignificant growth was found in 16/20 aerosol tubes: moulds in three, Pseudomonas species in one. Twelve of 19 chambers showed no or insignificant growth: moulds or yeasts were present in three and Pseudomonas sp. in four. In four of the seven patients moulds or yeasts and/or Pseudomonas sp. grew both from chambers and from aerosol tubes; in the remaining three only from chambers. None of these seven patients had followed our prescribed cleaning and disinfection recommendations, the other 13 claimed they had. Of the patients whose equipment yielded Pseudomonas sp, none was colonized with these strains, although one had P. aeruginosa. We conclude that our disinfection recommendations are adequate when followed. However, our disinfection recommendations concerning the nebulizing chamber had not been followed satisfactorily. The different forms of non-compliance would not have been detected without a home visit, emphasizing the importance of such visits. The importance of drying the equipment and of using the correct concentration of acetic acid is stressed.