Specimen collection. With each episode of clinically suspected VAP, the patient was subjected to four different sampling techniques within 12 hours of clinical diagnosis of VAP with an average of an hour between each procedure. All procedures including bronchoscopy were performed by same investigator. A set sequence of sampling was followed in each case with the ETA first, followed by BBS, then blind BAL, and BAL at the last. All patients were premedicated with midazolam and fentanyl prior to performing these sampling procedures unless they were already sedated and paralyzed.