The impact of culture site on length of stay among burn patients

Author(s):
Sarah Rehou; Shahriar Shahrokhi; Marc Jeschke

Background:

Thermal destruction of the protective skin barrier coupled with the immune response leads to the ideal environment for bacterial growth. Pseudomonas aeruginosa is a gram-negative organism that can grow a mature biofilm in about 10 hours. It is an opportunistic human pathogen and one of the most prevalent causes of sepsis and pneumonia in burn patients.

Hypothesis:

We hypothesized that patients with P. aeruginosa in systemic sites blood and/or sputum would have worse outcomes compared to patients with P. aeruginosa in localized sites.

Methods:

We included all adult (≥ 18 years) patients with an acute burn admitted to our burn centre between 2010 and 2016. Only patients with positive microbiology cultures of P. aeruginosa from wound swabs, biopsies, catheter tips, blood, and sputum sources were included. Clinical outcomes included morbidity, mortality, and hospital length of stay. We compared patients that had P. aeruginosa in localized sites like swabs, biopsies, and/or catheter tips to those that had P. aeruginosa in systemic sites like blood and/or sputum.

Results:

We studied 100 patients, mean age 51 ± 20 years and 33 ± 18% total body surface area (TBSA) burn, with 59 patients in the localized group and 41 in the systemic group. Demographics and injury characteristics were not significantly different among the localized and systemic group: mean age was 52 ± 19 versus 50 ± 22 (p=0.646) and 34 ± 20% versus 31 ± 15% TBSA burn (p=0.345), with the exception of the proportion of inhalation injury 22 (37%) versus 25 (61%) (p=0.025), respectively. The days to first P. aeruginosa culture post-injury was also not significant 16 ± 9 versus 16 ± 11 days (p=0.860). Length of hospital stay was significantly longer in the localized group, median 63 days (IQR 36-95 days) compared to the systemic group at median 41 (29-61 days) (p=0.007). Additionally, LOS/TBSA was also significantly longer in the localized group: 2.1 days per percent TBSA burn (IQR 1.5-2.9) versus 1.5 days per percent TBSA burn (IQR 1.1-2.5 days) (p=0.019).

Conclusions:

Patients with P. aeruginosa cultured from localized sites like swabs, biopsies, and/or catheter tips had significantly prolonged hospitalization compared with those that had P. aeruginosa in systemic sites of blood and/or sputum. This may be due to loss of skin grafts or impaired wound healing.