Regulatory Interpretation

Date:June 23, 2017

Subject: Regulatory Interpretation regarding Gram stained slides containing select agents

This is in response to your request, dated May 26, 2017 for the following regulatory interpretations for the preparation of a Gram stain slide using Burkholderia pseudomallei inside the biosafety cabinet (BSC) located in a registered room that is read on the microscope on the benchtop within the same room. 

  • Is the select agent considered outside of primary containment if viewed on the benchtop microscope? 

    No. The select agent is not considered a release outside of the primary barriers of the biocontainment area because the agent is fixed onto the slide or washed off during Gram staining procedure.

  • If not wearing respiratory protection, is the staff member “potentially exposed” for just viewing the slide on the microscope outside of primary containment?

    No. A staff member viewing a Gram stain slide of B. pseudomallei on a microscope within the same registered room would not be considered exposed to the select agent.  


Please note that:

  • The regulatory interpretation applies to Gram staining of all bacterial select agents.
  • If you want to remove Gram stained slides of select agents from registered space, you must validate in house that the Gram stained slides do not contain viable agent.