A case of thoracic empyema with gas formation associated with Streptococcus dysgalactiae subsp. equisimilis

A 63-year-old woman suffering from dyspnea since 1 week earlier underwent a combination therapy of oral corticosteroid and ciclosporin for rheumatic arthritis. Chest radiography showed plural effusion with gas formation in the right thorax. Empyema was diagnosed based on the specimen from pleural effusion. After a chest tube was emplaced to remove and wash out pus, antibiotics were started and empyema improved immediately. Streptococcus dysgalactiae subsp. equisimilis, but not aerobic bacilli, was detected from the pus by repeated culture. Insofar as we know this is the first case of empyema with gas formation associated with Streptococcus dysgalactiae subsp. equisimilis.