 Ventilator-associated pneumonia VAP is a common, life-threatening hospital-acquired infectious complication of prolonged mechanical ventilation MV. Despite aggressive efforts to prevent VAP, rates remain high because clinical diagnosis is imprecise and microbiological diagnosis is frequently delayed. Diagnosis of VAP depends on clinical signs as well as microbiologic evidence from Bronchioalveolar Lavage BAL cultures. Ordinarily, these cultures are only ordered after the patient presents with clinical signs and symptoms of VAP, which can significantly delay diagnosis and effective therapy. This research proposes to implement additional surveillance BAL cultures in order to reduce the time to diagnosis of VAP in mechanically ventilated critically ill adults. To further reduce the time to diagnosis of VAP, this research aims to test part of the BAL cultures using a novel flowcellsurface-capture device that allows direct from specimen visualization of bacteria using multiplexed automated digital microscopy BACcelTM for rapid bacterial identification and antibiotic resistance testing. Additionally, molecular assays of the BAL sample will characterize lower respiratory tract antimicrobial peptide host-innate immune molecule and local anti-oxidant defenses in mechanically ventilated adults at risk for VAP. 