Optimal duration of IV and oral antibiotics in the treatment of thoracic actinomycosis.

STUDY OBJECTIVE: IV antibiotic therapy for 2 to 6 weeks followed by 6 to 12 months of oral antibiotic therapy is usually recommended for the treatment of thoracic actinomycosis. The objective of this study was to evaluate the duration of IV and oral antibiotic therapy for thoracic actinomycosis.

METHODS: We present a retrospective case series of 28 patients with thoracic actinomycosis as confirmed by histopathology from October 1994 through December 2003.

RESULTS: After diagnosis of actinomycosis, 54% (15 of 28 patients) received antibiotic therapy alone. The duration of IV antibiotic therapy ranged from 0 to 18 days (median, 2 days; interquartile range [IQR], 0 to 3 days), and the duration of oral antibiotic treatment ranged from 76 to 412 days (median, 167 days; IQR, 142 to 214 days) in patients who received antibiotics alone. Combination surgical and antibiotic therapy occurred in 46% (13 of 28 patients). The duration of IV antibiotic therapy ranged from 3 to 17 days (median, 8 days; IQR, 5 to 13 days), and the duration of oral antibiotic therapy ranged from 0 to 534 days (median, 150 days; IQR, 3.5 to 289 days) in these patients. Clinical cures were achieved in 96% (27 of 28 patients). There was no clinical evidence of recurrence during follow-up period at our hospital (median, 23 months; IQR, 9 to 44 months) in 21 patients, excluding 7 patients who were transferred to referring hospitals after completion of antibiotic therapy (n = 6) or during antibiotic therapy (n = 1).

CONCLUSIONS: Thoracic actinomycosis is best treated with individualized therapeutic modalities, depending on factors such as the initial burden of disease, the performance of resectional surgery, and the clinical and radiologic responses to therapy. The traditional recommendation of IV antibiotic therapy for 2 to 6 weeks followed by oral antibiotic therapy for 6 to 12 months is not always necessary for all thoracic actinomycosis patients.