Mechanical ventilators as vehicles of infection

Twenty-five patients from the intensive care unit who had been subjected to tracheostomy and require mechanical respiration were studied. Data are presented concerning the bacteriological controls performed on the tracheal exudates, various parts of the ventilators (Engström Model 200 and Bennett PR-2), and the Wright spirometer. The germs found were mainly pseudomonas, enterobacteriaceae germs and bacteria from the acinetobacter group. There was a high incidence of infection in the tracheostomies of these patients. We found a cause and effect relationship between the contaminating bacteria isolated from the cannula and the bacteria isolated from the tracheal exudates in the case of pseudomonas aeruginosa. However, this was not found to be the case where enterobacteriaceae were concerned. Acinetobacter calcoaceticus were isolated almost exclusively in the ventilators. The study calls attention to the need for rigorous disinfection of ventilators to prevent hospital cross infections.