This is a prospective randomized study, which was carried on 100 patients in surgical Intensive Care Unit
requiring mechanical ventilation for more than 48 hours from June 2012 to November 2013. In two groups, suction was performed based
on the patients' need as well as physician's or nurses' decision on tracheal secretions. Patients randomly allocated into two groups (50
patients each): CTSS group and OTSS group. Patients were monitored for developing ventilator-associated pneumonia (VAP) during the
study. Throat samples were taken on admission and two times per week from each patient. Tracheal samples were performed during
endotracheal intubation, two times per week during mechanical ventilation and during extubation.