Time sequence of bacterial and fungal pathogens causing infections in trauma patients.

Purpose: A time sequence occurs in pathogens leading to infections in Intensive Care Unit (ICU) patients with a compromised immune system. A similar pattern may also occur in (multi)trauma patients characterized by similar impaired immunological responses. Such immune malfunction might be prolonged and enable hospital-acquired pathogens (selected through antibiotic regimens) to cause infections. This study investigated the timing of infections and associated pathogens in severely injured trauma patients.

Methods: A retrospective, single-center cohort study was conducted at a level-1 trauma center. Severely injured trauma patients from 2013 to 2022 with an ICU stay >48 hours were included. Infections compliant with the criteria of the Centers for Disease Control and Prevention and causative pathogens were documented. Timing of infections was scored as days after trauma.

Results: 109 out of 572 severely injured trauma patients developed infectious complications. All patients received antibiotics. A time sequence of pathogens that caused infections was observed. Staphylococcus aureus, Enterococcus spp., and CoNS were mainly responsible for infections before day 40 after trauma. From day 60 onward, Klebsiella spp., Candida spp., Enterobacter spp., and Pseudomonas spp. became more frequent.

Conclusion: A time sequence in occurrence of pathogens and associated infections was found in severely injured trauma patients. Commensal micro-organisms were predominant in the first weeks after trauma, which shifted toward hospital-acquired microorganisms over time. This observed time sequence is consistent with the hypothesis that a long-term imbalanced innate immune system facilitates infections with these normally non-pathogenic organisms during months after severe trauma.

Level of evidence: This was a retrospective cohort study with level III evidence.