necrotizing soft tissue infection can spread by trauma or hematogenously

This patient has spontaneous gas gangrene caused by Clostridium septicum, and the patient’s fulminant clinical presentation is consistent with a toxic shock syndrome. Clindamycin inhibits the toxin production of Clostridial species, and it also addresses the toxin-producing strains of Streptococci and Staphylococci that could cause a similar toxic shock presentation. Thus, the most important addition to his empiric antimicrobial regimen is clindamycin (choice B is correct).

This patient’s presentation should raise suspicion for a severe, necrotizing soft tissue infection and, specifically, gas gangrene (aka, Clostridial myonecrosis). He is presenting with acute extremity or muscle pain that eventually progresses to a dusky appearance and crepitus. Severe pain can precede any abnormal skin findings, and recognizing this feature of presentation is key to early recognition and appropriate treatment. The most important and primary emergent therapy for patients with suspected necrotizing soft tissue infection is surgical exploration and debridement, which should not be delayed. Appropriate empiric antibiotics, as discussed, are important but remain secondary in importance to timely surgical exploration.

This patient’s presentation suggests spontaneous Clostridial myonecrosis as the specific etiology of the soft tissue infection. Clostridial myonecrosis can be caused either by trauma or by spontaneous seeding of muscle through hematogenous spread. This patient’s colorectal malignancy is a well-recognized risk factor for spontaneous Clostridial myonecrosis, with the malignancy being the source of hematogenous spread of Clostridium from the GI tract to the muscle. The presence of crepitus on exam is also suggestive of Clostridial species as opposed to other causes of soft tissue infections, which may be less likely to produce gas.

Fungal pathogens can cause severe skin and soft tissue infection, but this is typically seen in patients with cellular immunodeficiency or other forms of immunocompromise. Thus, in the absence of this risk factor, empiric antifungal therapy is not recommended (choice A is incorrect).

Vibrio vulnificus is another potential cause of serious wound infections and sepsis. Both ciprofloxacin and doxycycline can be used to treat infections due to V vulnificus, but this patient’s case is more consistent with Clostridial myonecrosis and does not have the typical features of V vulnificus (choices C and D are incorrect). The typical presentation of V vulnificus is a wound that is exposed to salt water or shellfish (eg, in the setting of opening oysters), but this patient does not have a wound. Primary septic shock (ie, not wound-associated) due to V vulnificus infection can also be caused by eating raw shellfish, but this syndrome is seen most often in patients with underlying liver disease. Cases have also been reported in patients with comorbidities such as diabetes and chronic kidney disease. Doxycycline may be considered in the treatment of skin and soft tissue infections due to methicillin-resistant Staphylococcus aureus, but this patient is already receiving parenteral vancomycin, and doxycycline is not recommended for methicillin-resistant S aureus treatment in the context of a necrotizing soft tissue infection.12345

Footnotes

  1. SEEK Questionnaires ↩

  2. Arteta-Bulos R, Karim SM. Images in clinical medicine. Nontraumatic Clostridium septicum myonecrosis. N Engl J Med. 2004;351(17):e15. PubMed ↩

  3. Stevens DL, Bisno AL, Chambers HF, et al; Infectious Diseases Society of America. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-52. PubMed ↩

  4. Stevens DL, Maier KA, Mitten JE. Effect of antibiotics on toxin production and viability of Clostridium perfringens. Antimicrob Agents Chemother. 1987;31(2):213-218. PubMed ↩

  5. Stevens DL, Musher DM, Watson DA, et al. Spontaneous, nontraumatic gangrene due to Clostridium septicum. Rev Infect Dis. 1990;12(2):286-296. PubMed ↩