Influence of clinical history on airways bacterial colonization in subjects with chronic tracheostomy

Patients with chronic tracheostomy are subject to significant bacterial col onization of the airways, a risk factor for respiratory infections. The aim of our study was to verify whether bacterial colonization and humor al immune response in the airways can be influenced by the disease which le d to chronic respiratory failure and tracheostomy. Thirty-nine clinically stable outpatients with chronic tracheostomy were co nsidered: 24 were affected by chronic obstructive pulmonary disease (COPD) (mean age 66 years, range 54-78, M/F 19/3; months since tracheostomy 23, ra nge 3-62), 15 by restrictive lung disease (RLD) (12 thoracic wall deformiti es, three: neuromuscular disease; age 57 years. range 41-72; M/F 3/12, mont hs since tracheostomy 22, range 2-68). Recent antibiotic or corticosteroid treatments (<1 month) were among exclusion criteria. Bacterial counts were assessed in tracheobronchial secretions with the meth od of serial dilutions. Identification of bacterial strains was performed b y routine methods. Albumin. IgG, A, and M were measured in airways secretio ns with an immunoturbidimetric method. No significant differences were found between the two groups as regards eit her the quantitative bacterial cultures (RLD 81.4, 2.6-4200 x 10(4); COPD 7 5.9. 1.0-1530 x 10(4) colony forming units (cfu)/ml, geometric mean, range) or the prevalence of the main bacterial strains, (Pseudomonas species: 38 and 37%, Serratia marcescens: 31 and 23%, Staphylococcus aureus: 14 and 6 % , Proteus species: 3 and 8%, for RLD and COPD respectively) as a percentage of total strains isolated (RLD = 26, COPD = 48). Immunoglobulin levels did not show significant differences, apart from being higher in underweight s ubjects. We conclude that in our series of stable outpatients with chronic tracheost omy, bacteria-host interaction in the airways was not influenced by the cli nical history.