Anaerobic World In A Thoracic Environment: A Microanalysis of Empyema In The Severely Injured

Victoria Wagner; Vanessa Arientyl; Alejandro De Leon; Patricia Ayoung-Chee; Elizabeth Benjamin; S Rob Todd; Jason Sciarretta

Empyemas are known to be associated with pneumonia, trauma, and surgery. While the bacteriology of empyemas often centers on the inciting event or location of acquisition, specific factors may vary.

We hypothesize that anaerobic empyemas are associated with abdominal operations, chest tube placement in the ED, longer hospital and ICU length of stay (LOS), more ventilator days, and increased complications.

A retrospective cohort review of 34,020 patients between January 2019-December 2023 was performed. All empyemas post traumatic injury were clinically detected then confirmed by pleural cultures. Demographics, operative details, pleural cultures, pneumonia, hospital LOS, ICU LOS, ventilator days, complications, and deaths were collected.

35 patients comprised the cohort. Median (IQR) age was 38 (21.5-52) years. 92% were male with two-thirds resulting from blunt trauma and a median ISS of 26 (24.5-34). 45 unique pathogens were identified on pleural cultures. 72% were polymicrobial and 40% contained anaerobic growth (14/35). 13 cultures grew Staphylococcus sp. with 6 containing MRSA (13/35). Enterobacter sp. were the second most common aerobe (11/35). Prevotella sp. were the most common anaerobe (10/14). The most common yeast was Candida sp., with C. albicans making up 4/6 cultures. One culture grew mold (Rhizophus). 92% required surgical management. All anaerobic empyemas were treated operatively while 86% of aerobic empyemas were treated with surgery. 29% (10/35) of patients did not have a chest tube prior to empyema diagnosis. Of this group, 1/5 anaerobic patients had a procedure prior to empyema diagnosis (PEG tube), while 0/5 aerobic patients had a procedure prior. 9% of patients (3/35) had no chest trauma on admission (Chest AIS -). Location of chest tube placement (ED vs IR/OR/ICU) did not influence the type of bacteria grown (p=0.884). The presence of diaphragm injury also did not influence the type of bacterial growth (4 vs 4, p=0.685). Comparing aerobic/anaerobic vs aerobic growth alone, the aerobic group had more ventilator days (20 vs 34, p=0.015). There was no difference in hospital (43 vs 39, p=0.752) or ICU LOS (25.5 vs 39, p=0.235). Patients with aerobic pneumonia had higher incidence of DVT compared to the anaerobic group (0 vs 9, p=0.027). Overall mortality was 23% (8/35).

Critically injured trauma patients with empyemas have a notably high incidence of anaerobic growth, highlighting the importance of timely initiation of anaerobic coverage in patients with traumatic injuries and suspected empyemas. Patients with aerobic empyema experienced a higher incidence of DVTs, likely related to immobility secondary to increased ventilator days.