Empiric antimicrobial therapy for early-onset pneumonia in severe trauma patients

Purpose: The bacterial ecology involved in early pneumonia of severe trauma patients is mostly commensal and would allow wide use of narrow-spectrum antibiotics. We describe risk factors for treatment failure of severe trauma patients' pneumonia with the use of narrow-spectrum antimicrobial therapy in order to develop a score that could help clinicians to determine which patients might be treated with narrow-spectrum antibiotics.

Methods: A retrospective, observational, monocentric cohort study was conducted of severe trauma patients requiring mechanical ventilation for > 48 h and developing a first episode of microbiologically confirmed pneumonia occurring within the first 10 days after admission.

Results: Overall, 370 patients were included. The resistance rate against narrow-spectrum antibiotics (amoxicillin/clavulanic acid) was 22.7% (84 pneumonia). In a multivariate analysis, two independent risk factors were associated with this resistance: prior antimicrobial therapy ≥ 48 h (OR 4.00; 95 CI [2.39; 6.75]) and age ≥ 30y (OR 2.10; 95 CI [1.21; 3.78]). We created a prediction score that defined patient with one or two risk factors at high risk of resistance. This score presented a sensitivity of 0.92 [0.88; 0.94], a specificity of 0.33 [0.28; 0.38], a positive predictive value of 0.29 [0.24; 0.33] and a negative predictive value of 0.93 [0.90; 0.95].

Conclusion: Simple risk factors may help clinicians to identify severe trauma patients at high risk of pneumonia treatment failure with the use of narrow-spectrum antimicrobial therapy and, thus, use better tailored empiric therapy and limit the use of unnecessary broad-spectrum antimicrobial therapy.