Prospective controlled study of microbial colonization of the trachea in tracheotomized and laryngectomized patients with HME (heat and moisture exchanger)

Abstract

Conclusion: The use of heat and moisture exchangers (HMEs) does not endanger tracheostomy patients in terms of additional exposure to pathogenic microorganisms. Objective: Stoma filters in the form of HMEs cause a beneficial convection of respiratory air in tracheotomized and laryngectomized patients. We investigated whether or not this may lead to an altered microbial ecology in the non-physiologically colonized lower respiratory tract. Materials and methods: To test this hypothesis, material from the trachea of stoma patients was prospectively collected utilizing a standardized swab technique and subsequent aerobic quantitative culture assays of the suspended and serially diluted material. With this approach, we examined the microbial flora in 6 and 5 patients after laryngectomy/tracheostomy, respectively, without any protection, in 11 patients after laryngectomy with a bib, and in 8 laryngectomized patients with an HME. Results: In all three groups, Staphylococcus aureus and Candida albicans were most frequently demonstrated. The microbial count of facultative pathogenic agents ranged between 3×102 colony forming units (cfu)/ml and 106 cfu/ml and was similar in the three groups. With respect to the absence of inflammatory symptoms in every patient, all isolates could be regarded as colonizers. Among the antibiotics tested with each isolate, cefuroxime proved to be the most effective against the facultative pathogenic bacteria.