Background: Necrotizing fasciitis is a rare life threatening infection characterized by progressive tissue destruction that may involve subcutaneous fat, fascia, and/or muscle. Gram-positive cocci, specifically strains of Staphylococcus aureus and Streptococci, are responsible for the majority of these single-site source infections. Polymicrobial infections occur as well because of a combination of gram-negative and anaerobic involvement. This case report presents a rare case of necrotizing fasciitis being caused by coagulase negative staphylococcus epidermidis and corynebacterium.

Case Presentation: A 49-year-old male with past medical history of non-insulin dependent diabetes mellitus type 2 presented to the emergency department (ED) with a 2 day history of a progressively worsening right lower leg lesion. As per the patient, the lesion was initially erythematous and localized, but progressively expanded and began to develop bullae which prompted him to visit the ED. On arrival, the patient was tachycardic, febrile, and tachypneic. Labs were remarkable for leukocytosis with a neutrophilic predominance and an elevated blood glucose of 221. Blood cultures were collected and showed no growth in 5 days. However, wound cultures collected on the same day grew moderate corynebacterium and staph epidermidis within 24 hours. X-ray of tibia/fibula/ankle showed mild to moderate soft tissue edema about the medial malleolus and a small ankle joint effusion. Plastic surgery was consulted for bullae drainage and noted a large bullae on the medial aspect of the right tibia and erythema of the surrounding area. Wound debridement was recommended and performed on hospital day 4, 6, and 10. Intraoperative findings were consistent with necrotizing fasciitis, therefore muscular fascia was removed and split thickness autograft to the right leg was applied on hospital day 10, when intraoperative findings supported that the infection had resolved. Patient was treated with IV meropenem and doxycycline for 6 weeks and responded well to the autograft.

Discussion: Necrotizing fasciitis (NF) is typically caused by either a polymicrobial infection or Group A Streptococcus bacteria. Although diabetic patients tend to be susceptible to polymicrobial infections, it is very uncommon for the pathogens involved to only be those found on normal skin flora. Our case report shows that if there is a high index of suspicion, NF should still be considered even if wound cultures only grow bacteria typically present on normal skin flora. The aggressive progression of the infection despite the less common causative agents highlights the need for prompt recognition and intervention.