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Observational Study
. 2020 Jun 29;24(1):382.
doi: 10.1186/s13054-020-03092-1.

Biofilm formation on three different endotracheal tubes: a prospective clinical trial

Hulda R Thorarinsdottir  1   2 , Thomas Kander  3   4 , Anna Holmberg  5 , Sarunas Petronis  6 , Bengt Klarin  3   4
Affiliations
Observational Study

Biofilm formation on three different endotracheal tubes: a prospective clinical trial

Hulda R Thorarinsdottir et al. Crit Care. .

Abstract

Background: Biofilm formation on endotracheal tubes (ETTs) is an early and frequent event in mechanically ventilated patients. The biofilm is believed to act as a reservoir for infecting microorganisms and thereby contribute to development and relapses of ventilator-associated pneumonia (VAP). Once a biofilm has formed on an ETT surface, it is difficult to eradicate. This clinical study aimed to compare biofilm formation on three widely used ETTs with different surface properties and to explore factors potentially predictive of biofilm formation.

Methods: We compared the grade of biofilm formation on ETTs made of uncoated polyvinyl chloride (PVC), silicone-coated PVC, and PVC coated with noble metals after > 24 h of mechanical ventilation in critically ill patients. The comparison was based on scanning electron microscopy of ETT surfaces, biofilm grading, surveillance and biofilm cultures, and occurrence of VAP.

Results: High-grade (score ≥ 7) biofilm formation on the ETTs was associated with development of VAP (OR 4.17 [95% CI 1.14-15.3], p = 0.031). Compared to uncoated PVC ETTs, the silicone-coated and noble-metal-coated PVC ETTs were independently associated with reduced high-grade biofilm formation (OR 0.18 [95% CI 0.06-0.59], p = 0.005, and OR 0.34 [95% CI 0.13-0.93], p = 0.036, respectively). No significant difference was observed between silicon-coated ETTs and noble-metal-coated ETTs (OR 0.54 [95% CI 0.17-1.65], p = 0.278). In 60% of the oropharyngeal cultures and 58% of the endotracheal cultures collected at intubation, the same microorganism was found in the ETT biofilm at extubation. In patients who developed VAP, the causative microbe remained in the biofilm in 56% of cases, despite appropriate antibiotic therapy. High-grade biofilm formation on ETTs was not predicted by either colonization with common VAP pathogens in surveillance cultures or duration of invasive ventilation.

Conclusion: High-grade biofilm formation on ETTs was associated with development of VAP. Compared to the uncoated PVC ETTs, the silicone-coated and noble-metal-coated PVC ETTs were independently associated with reduced high-grade biofilm formation. Further research on methods to prevent, monitor, and manage biofilm occurrence is needed.

Trial registration: ClinicalTrials.gov NCT02284438 . Retrospectively registered on 21 October 2014.

Keywords: Alloys; Biofilm; Critical illness; Intratracheal; Intubation; Pneumonia; Polyvinyl chloride; Silicones; Ventilator-associated.

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Conflict of interest statement

This study was performed as part of a national project entitled Innovation against Infection (in Swedish: Innovation Mot Infektion [IMI]) and was conducted in collaboration with Skåne University Hospital, Lund, and RISE Research Institutes of Sweden, Borås, Sweden. The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Flow chart showing inclusion of patients in the study. “No consent” refers to cases in which the patient did not give consent to participate after the ICU stay. Endotracheal tube materials: PVC uncoated polyvinyl chloride; SC silicon-coated PVC; NbMC noble-metal-coated PVC
Fig. 2
Fig. 2
Scanning electron microscopy of biofilm formation on the surface of endotracheal tubes. a Typical low-grade (score < 4) biofilm formation. b Typical high-grade (score ≥ 7) biofilm formation (low magnification). c Colonies of microorganisms embedded in biofilm matrix (high magnification). d Scrape marks on the surface of an endotracheal tube probably caused by use of a suction catheter
See this image and copyright information in PMC

Comment in

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