Characterization of bacterial biofilms on tracheostomy tubes

To characterize the structure and microbial content of biofilms found on tracheostomy tubes. To determine the correlation between the patients' clinical condition and biofilm content.

Prospective observational series.

Tracheostomy tubes were collected from patients in both the inpatient and outpatient setting at an urban academic medical center. Sections of the tracheostomy tubes were evaluated by confocal microscopy and bacteria from them plated and identified. The number of colony forming units (CFUs) and species present were determined and a univariate analysis performed to correlate them with various clinical factors.

Bacteria were cultured from 19 of the 21 tracheostomy tubes collected. There were between 1 x 10(6) and 1 x 10(10) CFUs present in each of the 2 mm sections. Twelve different bacterial species and one fungus were isolated from culture and speciation. The number of bacteria isolated and the CFUs calculated varied in tubes obtained from the same patient at different times.

Biofilms were present on tracheostomy tubes in greater than 90% of tracheostomy tubes collected as early as 7 days after insertion in both the inpatients and outpatients. Although a variety of bacteria were identified in the biofilm, they often appeared as discrete microcolonies that appeared to be monospecies biofilm on confocal microscopy. There was a statistically significant inverse correlation between the number of colony forming units found and frequency of inner cannula change.