A Time-Dependent Analysis of Intensive Care Unit Pneumonia in Trauma Patients

Background: Appropriate and timely antibiotic therapy to treat pneumonia in trauma patients is extremely important. We evaluated the incidence and microbiology of pneumonia stratified by days postadmission and risk factors. Methods: Prospective data were collected on 714 trauma patients admitted to the intensive care unit over a 1-year period. Pneumonia was classified as community acquired (CAP) (≤ 3 days), early nosocomial (ENP) (4-6 days), or late nosocomial (LNP) (≥ 7 days). In addition, pneumonia was classified as CAP only, nosocomial only (NI), or combination (CAP and NI, or ENP and LNP) pneumonia. Strict institutional guidelines were followed for diagnosis. Results: One hundred eighty-two patients (25%) were diagnosed with 204 pneumonias over the study period. One hundred twenty-five (61%) of these pneumonias were ventilator associated. Staphylococcus aureus and Haemophilus influenzae were the most common pathogens isolated. Twenty-one percent of patients with CAP acquired an LNP (p < 0.025), in which Pseudomonas was the most common organism. Haemophilus caused LNP in 12% of patients. Cancer (p < 0.01), liver failure (p < 0.05), and age (p < 0.01) were predictive of nontypical pathogens in patients with CAP and ENP (p < 0.05). Obesity was most predictive of increased ventilator days (p < 0.091) and intensive care unit length of stay (p < 0.001). Increased age, alcohol abuse, and field airway were most predictive of mortality. Conclusion: Unanticipated pathogens were isolated in each class of pneumonia. The clinician must be aware of significant risk factors that may predispose patients to pathogens that are not ordinarily covered with standard antibiotic therapy.