Electron microscopic analysis of biofilm on endotracheal tubes removed from intubated neonates

Abstract

Objectives 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.