Efficacy and Safety of Prophylactic Antibiotics in Preventing Ventilator-associated Pneumonia: A Randomized, Double Blind, Placebo-controlled Trial

Inclusion Criteria: * • Age \> 18 years or older * Both sexes will be included. * Invasive mechanical ventilation Exclusion Criteria: * ongoing pneumonia or gross aspiration confirmed by the presence of lung infiltrates on chest radiographs at admission before invasive ventilation * previous lung disease precluding accurate interpretation of chest radiographs * ongoing antibiotic therapy or during the week before admission * known chronic colonization with multidrug-resistant bacteria * known allergy to beta-lactam antibiotics * Pregnancy