Experimental: FA Pneumonia Panel Guided Group

Patients in the FA Pneumonia Panel guided group will have a BioFire® FilmArray® Pneumonia Panel assay performed as soon as possible but within 24 hours of new antibiotic prescription for suspected respiratory infection in addition to all the investigations performed in standard care. Based on the rapid test results, antimicrobial therapy will be adjusted according to a pre-determined treatment algorithm and antimicrobial guidelines. The treatment algorithm and antimicrobial guidelines were based on the latest hospital antibiogram, procalcitonin protocol, and consensus recommendations from microbiologists, infectious disease experts and intensive care physicians at our hospital. The treating clinical team will also be given the standard microbiological culture with sensitivity results when available. The treating clinical team may override the pre-determined antimicrobial algorithm for any clinical reason at any time and the rationale will be recorded.

No_intervention: Standard Care Group

Patients in the standard care group will receive antimicrobial therapy guided by conventional microbiological cultures and standardized procalcitonin protocol. Choice of antimicrobial agent is based on use of the narrowest-spectrum antimicrobial agent possible according to culture sensitivity. Current standard investigations for any patient mechanically ventilated for suspected pneumonia in our ICU includes two sets of blood cultures, daily procalcitonin, respiratory specimen of tracheal aspirate or bronchoalveolar lavage for bacterial gram stain and cultures, respiratory viral PCR and urine streptococcus and legionella antigen. FA Pneumonia Panel will be performed from concurrent respiratory samples in the standard care group at the end of the study and the results will not be used by the treating clinical team for treatment decisions. Blinded results will only be available to the antimicrobial review panel for outcome assessment.