Colonization of oropharynx and lower respiratory tract in critical patients: Risk of ventilator-associated pneumonia

Objective: To investigate the microbial diversity existing in oral cavity and respiratory tract samples (from mini-bronchoalveolar lavage (BAL), endotracheal aspirate, and orotracheal tube) of patients on mechanical ventilation by using the checkerboard DNA-DNA hybridisation. Also, the study aimed to evaluate whether the microbial profile in the oral cavity is found in respiratory tract samples, at different periods of mechanical ventilation time (12 h, 48 h, 96 h) in attempt to identification of relationship between VAP (ventilator-associated pneumonia) and bacterial species studied. The last objective was to analyses correlation between blood cultures and VAP. Design: The samples were collected from ten patients in intensive care unit with medical prescription of orotracheal intubation and mechanical ventilation. Clinical data were tabulated and blood cultures were performed according medical indication. For checkerboard samples collection, chosen sites were the dorsal side of the tongue and gingival sulcus at 12 h, 48 h, 96 h, BAL, at 12 h, endotracheal aspirate at 48 and 96 h, and orotracheal tube at extubation time, when feasible. Results: It was possible to identify the presence of bacterial species in mouth and in the BAL/endotracheal aspirate. The data demonstrated an increase in the quantity of bacterial associated with prolonged use of mechanical ventilation (48 and 96 h). Conclusions: Bacterial species may migrate rapidly from mouth and upper airways during orotracheal intubation which contributes to the pathogenesis of VAP. There were associations between VAP and Enterococcus faecalis, Fusobacterium periodonticum, Gemella morbillorum, Neisseria mucosa, Propionibacterium acnes, Prevotella melaninogenica, Streptococcus oralis, Streptococcus sanguinis, Treponema denticola, Treponema socransckii, and Veillonella parvula.