CRP and bacterial pneumonia: This indicates that combinations of these markers can be useful to rule-out (BAL fluid total WBC count ≥510/μL or serum procalcitonin concentration ≥0.71 ng/mL with a sensitivity of 95.8% and negative likelihood ratio of 0.068) or rule-in (BAL fluid total WBC count ≥510/μL and serum C-reactive protein concentration ≥26.1 mg/dl with a specificity of 95.7% and positive likelihood ratio of 8.63) bacterial pneumonia.