Analysis of antibiotic use and clinical outcomes in adults with known and suspected pleural empyema

There is not a prevailing consensus on appropriate antibiotic choice, route, and duration in the treatment of bacterial pleural empyema after appropriate source control. Professional society guidelines note the lack of comparative trials with which to guide recommendations. We assessed clinical outcomes in the treatment of known and suspected empyema based upon three aspects of antibiotic use: (1) total duration, (2) duration of intravenous (IV) antibiotics, and (3) duration of anti-anaerobic antibiotics.

We performed a hypothesis-generating retrospective chart review analysis of 355 adult inpatients who had pleural drainage, via either chest tube or surgical intervention, for known or suspected empyema. The primary outcome variable was clinician assessment of resolution or lack thereof. The secondary outcomes were death within 90 days, hospital readmission within 30 days for empyema, and all-cause hospital readmission within 30 days. Mann-Whitney U test was used to compare outcomes with regard to these variables.

None of the independent variables was significantly associated with a difference in clinical resolution rate despite trends for total antibiotic duration and anti-anaerobic antibiotic duration. None of the independent variables was associated with mortality. Longer total antibiotic duration was associated with lower readmission rate for empyema (median 17 [interquartile range 11–28] antibiotic days in non-readmission group vs. 13 [6-15] days in readmission group), with a non-significant trend for all-cause readmission rate (17 [11–28] days vs. 14 [9–21] days). IV antibiotic duration was not associated with a difference in any of the defined outcomes. Longer duration of anti-anaerobic antibiotics was associated with both lower all-cause readmission (8.5 [0–17] vs. 2 [0–11]) and lower readmission rate for empyema (8 [0–17] vs. 2 [0–3]).

Our data support the premise that routine use of anti-anaerobic antibiotics is indicated in the treatment of pleural empyema. However, our study casts doubt on the benefits of extended IV rather than oral antibiotics in the treatment of empyema. This represents a target for future investigation that could potentially limit complications associated with the excessive use of IV antibiotics.