In adult mechanically ventilated ICU patients, what is the effect of using at least 5 of the VAP bundle which are the head of bed elevated, oral hygiene, assessment of sedation, peptic ulcer prophylaxis, cuff pressure control, endotracheal tube suctioning, and emptying of condensate on preventing the incidence of Ventilator-associated pneumonia compared to using less than 5 of the VAP bundle?