A decade of reduced gram-negative infections and mortality associated with improved isolation of burned patients
A. T. McManus, A. D. Mason Jr, W. F. McManus and B. A. Pruitt Jr
US Army Institute of Surgical Research, Ft Sam Houston, Tex.
OBJECTIVE: To compare the incidence of gram-negative bacteremia (GNB) and
mortality in patients with large burns (> or = 20% of total body
surface) hospitalized in either an open ward (OW) or a single-bed isolation
(IW) environment. DESIGN: Retrospective cohort study. SETTING: The US Army
Institute of Surgical Research, Burn Center, Ft Sam Houston, Tex. PATIENTS:
Two thousand five hundred nineteen consecutive patients with large burns
divided into two 10-year cohorts. Patients in the first cohort period were
treated under OW conditions; patients in the second cohort period, under IW
conditions. Infection (bacteremia) data were from a laboratory database. A
microbial surveillance system was used to monitor patient isolation.
Mortality was compared with predicted mortality derived by logistic
regression of outcome, burn size, and age of patients without bacteremia in
the study. MAIN OUTCOME MEASURES: Presence of GNB and survival. RESULTS:
The incidence of GNB was higher in the OW cohort (31.2%) than the IW cohort
(12.0%) (P < .001). The postinjury time of first GNB was delayed in the
IW vs the OW cohort (28.9 days vs 11.8 days, respectively) (P < .001).
For patients who had GNB in the OW cohort, mortality was higher than
predicted (observed-predicted mortality ratio, 1.61) (P < .001). Such
increased mortality was not present in the IW cohort. Multiple
antibiotic-resistant gram-negative pathogens were endemic in the OW cohort.
There was no evidence of cross infection or endemic conditions with
multiple antibiotic-resistant gram-negative pathogens in the IW cohort.
CONCLUSION: Improvements in isolation of burned patients were associated
with decreased incidence of GNB, delayed postinjury time of GNB, and
improved survival. Improved survival is likely related to decreased
susceptibility as a result of longer exposure to the benefits of treatment
and wound closure. These results suggest that, in patients with severe burn
injuries, gram-negative infections and the related mortality can largely be
prevented.
