Implications of endotracheal tube biofilm for ventilator-associated pneumonia

Objective: To determine the relationship between, and antibiotic resistance of, endotracheal tube (ET) biofilm and pulmonary pathogens in ventilator-a ssociated pneumonia (VAP). Setting: General intensive care units in two university teaching hospitals. Design: The microbiology of ET biofilm and tracheal samples from patients w ith and without VAP were compared. For individual patients, matching pairs of pathogens were confirmed as identical and characterised for antibiotic s usceptibility. Patients: 40 intensive care unit patients - 20 with VAP, 20 without VAP as control. The duration of intubation (median and range) was 6.5 days (3-17) and 5 days (2-10), respectively. Measurements and results: Samples of tracheal secretions were taken during ventilation for bacteriological culture. Following extubation, ETs were exa mined for the presence of biofilm. Isolates of high pathogenic potential in cluded Staphylococcus aureus, enterococci, Enterobacteriaceae, pseudomonads and Candida spp. Where the same microorganism was found on tracheal and ET samples by phenotyping, these were confirmed as identical by genotyping an d characterised for antibiotic susceptibility in both the free floating and biofilm forms. Seventy per cent of patients with VAP had identical pathoge ns isolated from both ET biofilm and tracheal secretions. No pairing of pat hogens was observed in control patients (p < 0.005). Susceptibility data fo r these pairs show that the ET acts as a reservoir for infecting microorgan isms which exhibit significantly greater antibiotic resistance than their t racheal counterparts. Conclusion: This investigation provides further evidence for the role of ET biofilm in VAP. The difficulty in eradicating an established microbial bio film using antibiotics implies that increased attention must be directed to wards modification of the ET to prevent or substantially reduce biofilm for mation.