ELECTRON MICROSCOPIC ANALYSIS OF BACTERIAL BIOFILM ON TRACHEAL TUBES REMOVED FROM INTUBATED NEONATES AND THE RELATIONSHIP BETWEEN BACTERIAL BIOFILM AND LOWER RESPIRATORY INFECTIONS

INTRODUCTION: Recurrent neonatal lower respiratory infections caused by endotracheal tubes (ETTs) may be related to the bacterial biofilm on them. OBJECTIVE: We aimed to investigate the microbial biofilm on the surface of ETTs removed from neonates with intubated ventilation to explore the relationship between ETT biofilm and the lower respiratory infections. METHODS: Twenty ETTs used in intubated neonates were examined for the presence of biofilm on their surface by scanning electron microscopy, and bacteria harvested from the surface of ETTs and the secretions of lower respiratory tracts were isolated, identified, and assessed for antimicrobial susceptibility. RESULTS: Scanning electron microscopy showed that the incidence of microbial colonization was 60% (12 of 20) when the use of tubes exceeded 2 days, biofilm formation was observed ∼3 days after intubation, and its architecture became more mature and complex when the duration exceeded 3 days. There were 14 positive cultures from ETTs (70%, including 4 normal flora), in which 7 kinds of pathogens were isolated; in 13 cultures from the secretions of lower respiratory tract (65%, including 1 normal flora), 10 kinds of pathogens were isolated. Seven samples had the same pathogen both on the surface of ETTs and in the secretions of the lower respiratory tract, which accounted for 50 of the positive cultures from ETTs. The Gram-negative bacteria isolated from the surface of ETTs and the secretions of lower respiratory tract presented multiresistance to antibiotics. CONCLUSIONS: The ETT biofilm develops into a mature and complex form on the basis of the duration of tube use. There is a possible positive correlation between them. There is correlation between microbial biofilm formation on the surface of ETTs and lower respiratory tract infection in intubated neonates who are ventilated for a prolonged period of time. ETT biofilm could be a likely source of recurrent infection.