AccessMedicine's Case of the Week: Pathogenic Bacteria

From: Sherris Medical Microbiology Cases

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A 24-year-old man, an automobile accident victim, was brought to the hospital with a compound fracture of the distal left tibia and fibula. Within 6 hours of the accident, the patient was taken to surgery where the wound was debrided, the leg was immobilized, and therapy was begun (cephalothin sodium IV, 1 g/4 h). The patient was afebrile. The hematocrit reading was 41%, the WBC count 10 900/mm3, and blood pressure and pulse rate within normal limits. He did well until the fourth postoperative day when he was noted to have a temperature of 38.3°C orally, a tachycardia rate of 120 bpm, a painful left leg, and a sense of impending doom.

The cast was opened and the entire lower leg was found to be swollen and reddish-brown, and was exuding a serosanguineous foul-smelling discharge. Crepitations were palpable over the anterior tibial and entire gastrocnemius areas. His blood pressure became unstable and then dropped to 70/20 mm Hg. A Gram stain of an aspirate from the gastrocnemius demonstrated both gram-negative and gram-positive rods, but no spores were seen. At this time, the hematocrit reading had decreased to 35%, and WBC count was 12 000/mm3, with 85% polymorphonuclear leukocytes.

Therapy was begun with IV penicillin G aqueous, 5 million units every 6 hours. The man was taken to surgery, where an above-knee amputation was performed. While the patient was receiving cephalothin, cultures of the necrotic muscle grew E coli and C perfringens. Within 3 hours after amputation, the patient had a sense of well-being, and complete recovery followed.

Question 1 of 4:

1.The crepitations in the wound are most likely due to:

  A - Production of CO2 by Clostridium perfringens

  B - Bowel leakage into the tissue

  C - Foreign bodies from the accident

  D - Surgical introduction of air

  E - Local hematoma

Click HERE to answer the questions and complete the case!

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Julie Grishaw, ACNP

Senior Editor, McGraw-Hill Education