Value of C-Reactive Protein in the Detection of Bacterial Contamination at the Time of Presentation in Drug-Induced Aspiration Pneumonia

Study objective To compare the plasma concentration of C-reactive protein (CRP) with traditional markers for diagnosis of bacterial pneumonia in patients with suspected aspiration. Design Prospective, nonrandomized, controlled study of consecutive hospital admissions. Setting Toxicology ICU in a university hospital. Patients or participants Acutely poisoned comatose patients admitted to the hospital with suspicion of aspiration pneumonia. Interventions Distal protected catheter sampling per fiberoptic bronchoscopy and bacteriologic culture were employed as a standard to detect the bacterial component of suspected aspiration pneumonia. Plasma CRP concentrations, temperature, and WBC count were measured on hospital day 1. Measurements and results Sixty-six patients were evaluated. Thirty-two had bacterial contamination by positive culture (≥10 3 cfu/mL). Multiple receiver-operating characteristic (ROC) curves were used to compare each parameter for detection of infection secondary to aspiration. The ROC curve of CRP concentrations showed that a CRP >75 mg/L is associated with bacterial contamination with a sensitivity of 87%, specificity of 76%, positive predictive value of 78%, and negative predictive value of 87%. ROC curves of temperature and WBC count demonstrated poor diagnostic value of these markers in indicating the bacterial component of suspected aspiration pneumonia. Conclusions Early measurement of CRP is useful for the diagnosis of aerobic bacterial content of aspiration pneumonia and perhaps in determining the need for invasive bacteriologic sampling. Temperature and WBC count are poor indicators of bacterial infection of aspiration pneumonia in poisoned patients.