Gram – Deep Toe Wound: gram positive bacilli (Clostridium perfringens) – no cells – Shipped May 16, 2016


A simulated deep toe wound smear collected from a 50 year old diabetic patient with a possible gangrenous toe was sent to category A, B, C, and C1 laboratories. Participants were expected to report the presence of gram positive bacilli and the absence of cells.


  1. The direct examination of a Gram-stained smear of the wound is vital to support early clinical diagnosis of clostridial myonecrosis (gas gangrene).
  2. Anaerobes are easily over-decolourized in the Gram-stain and without the absence of neutrophil or epithelial cell staining to judge the quality of the Gram-stain it can make its interpretation challenging. However, despite the gram variable staining the distinctive morphology of uniform, large box-car rods with the absence of neutrophils should question gram negative or gram variable staining, and consideration should be given to repeating the stain or making the call as gram positive.


Full critique (PDF)

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