replacement was initiated. A hormonal study was performed showing increased levels of TSH (31.59), antibodies antiperoxidase (>1000 UI/mL) and decreased levels of thyroxine (<0.28 ng/dL). Moreover, the antinuclear antibodies were positives. The patient was diagnosed of systemic lupus erythematosus and myxedematous coma. Later, a chest ultrasound revealed a left pleural effusion; drainage was then performed.Both pleural fluids were sent to the microbiology laboratory for culture. The two samples were inoculated onto both aerobic and anaerobic blood agar (Becton Dickinson), chocolate agar (Becton Dickinson), and thioglycolate broth (Becton Dickinson), incubating all media at 37º C for 5 days. Gram staining of both fluids exhibited abundant Gramnegative rods. On the second day of incubation, numerous Two rare cases of pleural infection due to Prevotella species