BAL samples will be cultured by standard methods and the minimal inhibitory concentration (MIC) of bacteria to the usual antibiotics will be determined using standard procedures. At the time of BAL collection, a rapid antibiogram will be performed by placing E-test antibiotic strips (AB Biodisk) directly onto Mueller-Hinton agar plates seeded with the BAL specimen (both by flooding and swabbing). E-test strips will be impregnated with cefoxitin, piperacillin-tazobactam, cefepime, imipenem, ciprofloxacin and amikacin. At 24 h, the E-test plates will be photographed and then examined separately by both a bacteriologist and a medical ICU physician following a consensus method. The final E-test results will be compared with the standard MIC cultures.