Endotracheal tube biofilm in critically ill patients during the COVID-19 pandemic : description of an underestimated microbiological compartment

Abstract

Biofilm (BF) growth is believed to play a major role in the development of ventilator-associated pneumonia (VAP) in the intensive care unit. Despite concerted efforts to understand the potential implication of endotracheal tube (ETT)-BF dispersal, clinically relevant data are lacking to better characterize the impact of its mesostructure and microbiological singularity on the occurrence of VAP. We conducted a multicenter, retrospective observational study during the third wave of the COVID-19 pandemic, between March and May 2021. In total, 64 ETTs collected from 61 patients were included in the present BIOPAVIR study. Confocal microscopy acquisitions revealed two main morphological aspects of ETT-deposited BF: (1) a thin, continuous ribbon-shaped aspect, less likely monobacterial and predominantly associated with Enterobacter spp., Streptococcus pneumoniae or Viridans streptococci, and (2) a thicker, discontinuous, mushroom-shaped appearance, more likely characterized by the association of bacterial and fungal species in respiratory samples. The microbiological characterization of ETT-deposited BF found higher acquired resistance in more than 80% of analyzed BF phenotypes, compared to other colonization sites from the patient's environment. These findings reveal BF as a singular microbiological compartment, and are of added clinical value, with a view to future ETT-deposited BF-based antimicrobial stewardship in critically ill patients. Trial registration NCT04926493. Retrospectively registered 15 June 2021.

Figure 1

Flow chart for study screening and inclusion of ETT collection.

Figure 2

Mesostructural characterization of ETT-deposited BF. (A) Macroscopic view of ETT section before confocal microscopy ; (B) confocal image of an ETT section showing ribbon-shaped BF deposited on the inner surface (scale bar, 75 µm) ; (C) confocal image of an ETT section showing mushroom-shaped BF deposited on the inner surface (scale bar, 75 µm) ; (D) zoomed confocal image of an ETT section showing ribbon-shaped BF deposited on the inner surface (scale bar, 25 µm) ; (E) zoomed confocal image of an ETT section showing mushroom-shaped BF deposited on the inner surface (scale bar, 25 µm) ; (F) correlation curve between the length of MV duration and BF thickness ; (G) comparison of median MV duration between ribbon- and mushroom-shaped BF ; H. comparison of median BF thickness between ribbon- and mushroom-shaped BF. BF biofilm, ETT endotracheal tube, MV mechanical ventilation, ns not significant.

Figure 3

Microbiological characterization of ribbon- and mushroom-shaped ETT-deposited BF. (A) compared percentage of ETT retrieving both bacterial and fungal species between ribbon- and mushroom-shaped ETT-deposited BF ; (B) compared number of both bacterial and fungal species between ribbon- and mushroom-shaped ETT-deposited BF ; (C) compared distribution of both bacterial and fungal species between ribbon- and mushroom-shaped ETT-deposited BF. BF biofilm, ETT endotracheal tube, ns not significant. Other (microbiological species retrieved < 5%) : Candida kefyr, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, Citrobacter freundii, Enterobacter cancerogenus, Enterococcus durans, Klebsiella aerogenes, Klebsiella variicola, Lactobacillus gasseri, Lactobacillus paracasei, Lactobacillus rhamnosus, Morganella morganii, Neisseria mucosa, Propionibacterium acnes, Proteus mirabilis, Pseudomonas oryzihabitans, Raoultella ornithinolytica, Serratia rubidae, Staphylococcus hominis, Stenotrophomonas maltophilia.

Figure 4

Microbiological characterization of ETT-deposited BF in comparison to respiratory samples (TBA-BAL). (A) compared percentage of ETT retrieving both bacterial and fungal species between ETT-deposited BF and respiratory samples; (B) compared number of both bacterial and fungal species between ETT-deposited BF and respiratory samples ; (C) compared distribution of both bacterial and fungal species between ETT-deposited BF and respiratory samples. BAL bronchoalveolar lavage, BF biofilm, ETT endotracheal tube, ns not significant, TBA tracheobronchial aspirate. Other (microbiological species retrieved < 5%) : Candida kefyr, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, Citrobacter freundii, Enterobacter cancerogenus, Enterococcus durans, Klebsiella aerogenes, Klebsiella variicola, Lactobacillus gasseri, Lactobacillus paracasei, Lactobacillus rhamnosus, Morganella morganii, Neisseria mucosa, Propionibacterium acnes, Proteus mirabilis, Pseudomonas oryzihabitans, Raoultella ornithinolytica, Serratia rubidae, Staphylococcus hominis, Stenotrophomonas maltophilia.

Figure 5

Microbiological species either retrieved or lost from BF analysis in comparison to respiratory samples (TBA-BAL) or global colonization (TBA-BAL, CVC-AC, urinalysis and other colonization/infection sites). (A) number of microbiological species either retrieved or lost from BF analysis in comparison to respiratory samples for each patient ; (B) absolute value of the median number of microbiological species either retrieved or lost from BF analysis in comparison to respiratory samples, all patients combined ; (C) number of microbiological species either retrieved or lost from BF analysis in comparison to global colonization for each patient ; (D) absolute value of the median number of microbiological species either retrieved or lost from BF analysis in comparison to global colonization, all patients combined ; (E) lost and found differential for BF microbiological species in comparison to respiratory samples or global colonization for each patient ; (F) absolute value of the median lost and found differential for BF microbiological species in comparison to respiratory samples or global colonization, all patients combined. AC arterial catheter, BAL bronchoalveolar lavage, BF biofilm, CVC central veinous catheter, TBA tracheobronchial aspirate.