Electron Microscopic Analysis of Biofilm on Endotracheal Tubes Removed from Intubated Neonates

Abstract

OBJECTIVE: To determine if the phenomenon of biofilm accumulation and associated microbial colonization occurs on the surface of endotracheal tubes in the region of the subglottis in neonates. METHODS: Endotracheal tubes removed from 9 consecutive neonatal patients intubated for more than 12 hours were processed (range, 13 hours to 8 days). A sterile control tube was also processed. For each, the portion of the endotracheal tube that had been in contact with the subglottis was determined using a previously published nomogram. A 1-cm-long cross-sectional segment of the endotracheal tube corresponding to the level of the subglottis was divided into 2 portions for both electron microscopy and aerobic/anaerobic cultures. RESULTS: Two of 9 (22%) luminal surface cultures grew Staphylococcus species, 1 (11%) grew normal flora, and 6 (66%) had no growth. Three of 9 (33%) outer-surface cultures grew Staphylococcus species, 1 (11%) had gram-negative rods on staining but a sterile culture, and one enterococcal contaminant was found. Electron microscopy revealed that 8 of 9 inner lumen surfaces harbored bacteria and biofilm formation. All outer lumen surfaces had biofilm formation; 6 of 9 had bacterial colonization. There was no obvious difference in the appearance of the inner and outer tube surface accretions. No time-dependent differences were noted except of the longest indwelling tube (8 days). CONCLUSION: This study demonstrates for the first time the presence of biofilm on the outer surface of neonatal endotracheal tubes. The data suggest that the presence of bacteria and/or biofilm does not correlate with other traditional indicators of microbial colonization.