We present two cases of invasive infection caused by Streptococcus dysgalactiae subsp. equisimilis, one that showed rapidly developing necrotizing fasciitis in a previously healthy man and one that showed severe cellulitis and septic shock even though the bacterium possessed a mutated emm gene, predicted to encode a truncated M protein.
CASE REPORTPatient 1 was a 48-year-old, previously healthy man admitted to Haukeland University Hospital in Western Norway with a fever and a rapidly spreading erythema of the skin overlying his right knee. The symptoms were preceded by a minor trauma toward the right knee 5 h prior to admission, leading to a disruption of the skin barrier. Blood pressure upon admission was 127/68 mm Hg, pulse rate 90/min, and temperature 39.6°C. Blood cultures were taken, and intravenous treatment with penicillin G at 5 million IU four times a day (q.i.d.) and clindamycin at 900 mg three times a day (t.i.d.) was started. Surgical exploration was performed 2 h later because of rapid deterioration of the patient's condition, and necrotic subcutaneous tissue and fascia of the lateral margin of the patella and the upper part of the calf were excised. Hypotension (blood pressure, 85/45 mm Hg) developed postoperatively, and normal blood pressure was reestablished after 5 to 6 h of intensive intravenous fluid therapy. Neither renal, hepatic, nor respiratory failure developed. The international normalized ratio (INR; normal range, Ͻ1