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Objective: Streptococcus milleri, a virulent pathogen, is the leading isolate in the pleural fluid of thoracic empyema patients. S. milleri has been associated with significant morbidity and mortality and is particularly pyogenic, leading to abscess formation. Our purpose was to compare the clinical outcomes of patients with Streptococcus milleri pleural empyemas to patients with Non-S. milleri empyemas.
Design: Retrospective Case-Control Study
Setting: Tertiary Care Academic Center
Patients:
Method of identification: ICD-9 Codes for pleural empyema
Exclusion criteria: 18 or younger
Time period: May, 2006 - April 2011
From a total of 195 patients identified, 190 had pleural fluid culture results available for review, with 42 testing positive for S. milleri. There was no difference between the S. milleri and the Non-S. milleri groups with regards to age, sex, smoking habit, underlying cancer or diabetes.
Interventions:
Chest tube placement
Operative decortication.
Main Outcome Measures:
Length of stay
Readmission (30 days)
Reoperation (6 months)
Mortality
Results: The S. milleri group had more frequent surgical interventions and a significantly shorter average length of stay than the cohort group. The S. milleri group was 4 times more likely to have a polymicrobial empyema. Polymicobial S. milleri empyemas were most often co-infected by an anaerobe.
Conclusion:
Ours is the largest series of S. milleri pleural empyemas in the U.S. Contrary to their previously described poor prognosis, we found that patients with S. milleri empyemas had a better outcome than those with Non-S. milleri pleural infections. Our findings also confirm S. milleri’s synergy with anaerobes. We believe that our favorable results for S. milleri empyema patients is due to our routine use of broad-spectrum antibiotics as well as early operative intervention.