Eradication of P. aeruginosa biofilm in endotracheal tubes based on lock therapy: results from an in vitro study

María Jesús Pérez-Granda,Rafael Samaniego,María Consuelo Latorre,Javier Hortal,María Guembe,Beatriz Alonso,Emilio Bouza

doi:10.1186/s12879-017-2856-0

Abstract

BackgroundDespite the several strategies available for the management of biofilm-associated ventilator-associated pneumonia, data regarding the efficacy of applying antibiotics to the subglottic space (SS) are scarce. We created an in vitro model to assess the efficacy of antibiotic lock therapy (ALT) applied in the SS for eradication of Pseudomonas aeruginosa biofilm in endotracheal tubes (ETTs).MethodsWe applied 2 h of ALT to a P. aeruginosa biofilm in ETTs using a single dose (SD) and a 5-day therapy model (5D). We used sterile saline lock therapy (SLT) as the positive control. We compared colony count and the percentage of live cells between both models.ResultsThe median (IQR) cfu counts/ml and percentage of live cells in the SD-ALT and SD-SLT groups were, respectively, 3.12 × 105 (9.7 × 104-0) vs. 8.16 × 107 (7.0 × 107-0) (p = 0.05) and 53.2% (50.9%-57.2%) vs. 91.5% (87.3%-93.9%) (p < 0.001). The median (IQR) cfu counts/ml and percentage of live cells in the 5D-ALT and 5D-SLT groups were, respectively, 0 (0-0) vs. 3.2 × 107 (2.32 × 107-0) (p = 0.03) and 40.6% (36.6%-60.0%) vs. 90.3% (84.8%-93.9%) (p < 0.001).ConclusionWe demonstrated a statistically significant decrease in the viability of P. aeruginosa biofilm after application of 5D-ALT in the SS. Future clinical studies to assess ALT in patients under mechanical ventilation are needed.

Highlights

Despite the several strategies available for the management of biofilm-associated ventilator-associated pneumonia, data regarding the efficacy of applying antibiotics to the subglottic space (SS) are scarce
The median (IQR) percentage of live cells detected by confocal laser scanning microscopy (CLSM) was 53.2% (50.9%-57.2%) in the single dose (SD)-antibiotic lock therapy (ALT) group and 91.5% (87.3%-93.9%) in the SD-saline lock therapy (SLT) group (p < 0.001) (Fig. 2a, b)
The samples of endotracheal tube (ETT) segments observed under CLSM showed a similar biomass thickness in P. aeruginosa biofilm for both single dose of ALT (SD-ALT) and SD-SLT, as shown by Scanning electron microscopy (SEM)

Summary

Introduction

Despite the several strategies available for the management of biofilm-associated ventilator-associated pneumonia, data regarding the efficacy of applying antibiotics to the subglottic space (SS) are scarce. We created an in vitro model to assess the efficacy of antibiotic lock therapy (ALT) applied in the SS for eradication of Pseudomonas aeruginosa biofilm in endotracheal tubes (ETTs). Bacterial biofilm is thought to be responsible for the development of respiratory infections in more than 80% of cases, with approximately 106 bacterial cells/cm recovered from the endotracheal tube (ETT) [3]. In. The various strategies for the prevention and treatment of VAP-associated biofilm include selective digestive decontamination (SDD), subglottic aspiration, antimicrobial drug–coated tubes, and devices that help to remove mucus, all of which can reduce biofilm formation in intubated patients [6,7,8,9,10,11,12]. Despite the combination of compounds in the SDD solution would cover most microorganisms causing VAP and it even has not been associated to an increase of antibiotic resistance [17,18,19,20], it appears that SDD alone

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