A 70-year-old man is hospitalized due to abrupt-onset, severe left thigh pain with no preceding trauma. Temperature is 38.9 C (102 F), blood pressure is 90/60 mm Hg, pulse is 120/min, and respirations are 24/min. Left thigh examination shows diffuse swelling with dusky skin discoloration and several bullae filled with hemorrhagic fluid. There is significant tenderness and crepitus on palpation. Gram staining of the bullae fluid reveals numerous gram-positive rods, and subsequent culture grows Clostridium septicum. Which of the following is the greatest risk factor for this patient's current condition?

Question

A 70-year-old man is hospitalized due to abrupt-onset, severe left thigh pain with no preceding trauma.  Temperature is 38.9 C (102 F), blood pressure is 90/60 mm Hg, pulse is 120/min, and respirations are 24/min.  Left thigh examination shows diffuse swelling with dusky skin discoloration and several bullae filled with hemorrhagic fluid.  There is significant tenderness and crepitus on palpation.  Gram staining of the bullae fluid reveals numerous gram-positive rods, and subsequent culture grows Clostridium septicum.  Which of the following is the greatest risk factor for this patient's current condition?

Quizplus · Accepted Answer

Clostridium septicum is a spore-forming, exotoxin-producing, gram-positive bacterium that is a normal commensal of the gastrointestinal tract in humans. Although the organism is largely nonpathogenic, breakdowns in the gastrointestinal mucosa can lead to invasion with subsequent hematogenous dissemination to healthy muscle tissue, resulting in spontaneous gas gangrene (nontraumatic). Manifestations include rapid-onset muscle pain, fever, hemorrhagic bullae with dusky surrounding skin, and tissue edema/crepitus. Urgent antibiotics and surgery are required, as the infection is often fatal even with early treatment. Most cases of spontaneous gas gangrene are triggered by an underlying colonic malignancy, which creates a portal of entry for the bacteria. Inflammatory bowel disease and immunosuppression are also risk factors. Unlike C septicum gas gangrene, C perfringens gas gangrene is usually associated with preceding trauma. (Choice B) Patients with hemochromatosis are at increased risk for fulminant Vibrio vulnificus infections (the organism is dependent on free iron for growth). Although V vulnificus can cause rapid-onset sepsis and bullous skin lesions, it is a gram-negative bacterium. In addition, most infections occur due to shellfish consumption or wound contamination with seawater. (Choice C) Indwelling vascular catheters increase the risk for candidemia, which can cause sepsis, abscesses, and pustular skin lesions on an erythematous base. (Choice D) Multiple myeloma impairs lymphocyte function and reduces the ability of plasma cells to generate normal immunoglobulin, which increases risk of infection. Pneumonia due to Streptococcus pneumoniae and Haemophilus influenzae and urinary infections due to Escherichia coli are most common. (Choice E) Recent antibiotic use increases the risk of C difficile infection, which usually presents with diarrhea, fever, and abdominal pain. Educational objective: Clostridium septicum is a spore-forming, exotoxin-producing, gram-positive organism that is the most common cause of spontaneous gas gangrene (eg, rapid-onset pain, hemorrhagic bullae, tissue crepitus). Underlying colonic malignancy is the greatest risk factor for infection.

A 70-Year-Old Man Is Hospitalized Due to Abrupt-Onset, Severe Left