Joint Fluid: Clostridium perfringens  – Shipped August 13, 2018


A simulated joint fluid sample collected from 27 year old athlete, post arthroscopy on knee was sent to category A laboratories. Participants were expected to report the presence of Clostridium perfringens.



  1. While uncommon as a cause of septic joint infection, the presence of C. perfringens in the joint following arthroscopy should be considered a medical emergency, and every effort made to contact the clinician directly both for the initial Gram smear and subsequent culture identification. Presumptive double-zone hemolysis will likely be observed within 24hr of sample inoculation (C. perfringens grows rapidly) and can be reported at that time as a presumptive C. perfringens positive culture.
  2. Some cells from the gram smear and primary culture may appear to lose their Gram reaction, but the typical boxcar morphology of the cells should still point to C. perfringens unless proven otherwise.

Full critique (PDF)

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