Scanning Electron Microscopic Biofilm Grading and Ventilator Associated Pneumonia in Relation to Duration of Intubation

Abstract

Background: Ventilator associated pneumonia (VAP) accounts for 7-70% of infections in intensive care units (ICUs) leading to increase in hospitalization, mortality and cost. Endotracheal tube (ETT) is a risk factor for developing VAP caused by biofilm producing organisms resistant to antimicrobial agents. This study aimed to determine guidelines for ETT extubation through detection of biofilm formation and development of VAP. Objectives: Our aim was to assess biofilm formation on the luminal surface of ETTs in intubated patients in ICU in relation to duration of intubation bacteriologically and morphologically using Scanning Electron Microscope (SEM). Antimicrobial resistance and VAP development were also studied. Methodology: Our work was conducted on 20 ETTs divided into two groups: Group (1); 8 patients with ETTs<5 days, and group (2); 12 patients with ETTs of 5-12 days. Culture of the interior of the ETTs, identification of bacterial species, antibiotic susceptibility and presence with staging of biofilm into 3 grades by SEM were performed. Results: A highly significant relationship was observed between the duration of intubation and biofilm grading (p value <0.001). Also, the duration of intubation and VAP development were significantly correlated (p<0.001). A highly significant relationship was observed between VAP development and biofilm grading by SEM (p<0.001). A moderate significant relationship was found between VAP development and prognosis of patients (p<0.02). It was also observed that prolonged intubation was associated with prevalence of polymicrobial colonization with the predominance of Gram negative bacilli. Furthermore, a moderate significant relationship was observed between antimicrobial resistance and both biofilm grading and duration of intubation (p<0.02). Conclusion: Biofilm formation and grading as well as bacterial colonization with multidrug-resistant (MDR) bacteria were time dependent in patients on mechanical ventilation in ICU which may enhance their morbidity and mortality rates. Also a role of ETT biofilm is emphasized in the pathogenesis and prognostic outcome of VAP in patients intubated for a prolonged period. Accordingly, we recommend that ETT should be exchanged every 4 days to avoid such morbidity and mortality consequences.