When it comes to cleaning a PEC, there are different schools of thought. This blog post is dedicated to introducing best cleaning practices while taking into consideration different styles of PECs with different airflows. However, prior to getting into the dynamics of how to clean and disinfect a PEC, knowledgebase on cleaning agents and their appropriate use must be established. (If a review on cleaning product and frequency of use is not needed, please advance to the last section “Cleaning and Disinfecting the PEC”).
The 3 sections of this blog cover:
Review of Cleaning Agents
Frequency of Cleaning and Disinfecting the PEC
Cleaning and disinfection the Primary Engineering Control (PEC)
Review of Cleaning Agents:
Definitions for cleaning agents vary slightly from one organization to the next. However, sterile compounders will focus on definitions from USP <797> since it sets the minimum standard for sterile compounding. A summary on cleaning agents appears in the table and bullet points below:
Note: Only sterile cleaning agents and supplies (i.e., sterile low-lint wipers) may be used inside the PEC.
Cleaning Agent: A product that removes organic/inorganic substances, using a mechanical process, usually containing a surfactant. It’s important to note the two distinguishing factors. The surfactant allows for encapsulation of organic and inorganic substances so that they can be easily wiped away with the mechanical process. Sterile isopropyl alcohol (IPA) 70% would not be an appropriate USP <797> defined cleaning agent because it lacks a surfactant.
Disinfecting Agent: A product that has appropriate germicidal action (EPA-registered in the United States), destroying microorganisms (bacteria, virus, fungi). Sterile IPA 70% would not be an appropriate disinfectant because it lacks some microbicidal activity.
Sporicidal Agent: Use of a sporicidal is a part of disinfection, specifically pertaining to the act of destroying and removing spores and/or spore-forming microbes. Sterile IPA 70% does nothing to destroying spores and therefore cannot even be considered.
Dwell time: This is the amount of time a product (cleaner, germicidal, sporicidal) must remain on a surface to be effective at its stated claim(s). This is an EXTEREMELY important concept.
One-Step Agents: Although cleaning and disinfection are individual steps, there are acceptable combination products on the market that deliver a one-step process, greatly increasing efficiency around cleaning and disinfecting. These are marketed as one-step EPA-registered cleaner disinfectants and sporicidal disinfectant cleaners. It is also important to note that these one-step products are to be used on surfaces that have no visible soiled areas. For visibly soiled areas, sterile water for injection/irrigation may be used to remove debris prior to use of the agent. Alternatively, that agent may be applied twice, once to remove visible contamination and the second time for disinfection.
Sterile IPA 70%: IPA 70% on its own is used for its sanitization properties and plays an important role to keep microbial growth down to acceptable levels in between cleaning and disinfection processes. Additionally, it acts as an effective product for removal of residues left behind by cleaning agents.
Frequency of Cleaning and Disinfection of the PEC:
Only sterile cleaning agents and supplies (i.e., sterile low-lint wipers) may be used inside the PEC. Cleaning and disinfecting of the PEC occurs at minimum frequencies outlined in USP <797> and summarized in the table below. For cleaning and disinfecting of C-PECs, for compounding of sterile hazardous drugs, USP <800> must be taken into consideration to include deactivation and decontamination prior to cleaning and disinfection.
It is important to point out that these are minimum standards, and it is up the facility to assess more needs for more frequently cleaning, disinfecting and sporicidal use.
Cleaning and Disinfecting the Primary Engineering Control (PEC):
It is important to remember that the order in which cleaning agents are used is important. Cleaning is done prior to disinfecting to remove dirt, debris, and excessive microbial growth so that the disinfecting agent has full contact with the microbes on the surface being cleaned. It is recommended to use a one-step EPA-registered cleaner disinfectants and/or sporicidal disinfectant cleaners to greatly increase efficiently of the entire cleaning and disinfecting process.
The direction of airflow will determine the how to clean the PEC. In general, cleaning will occur moving from top to bottom, from the interior areas to the opening of a PEC and moving away from HEPA filtered air.
Horizontal Laminar Air Flow System (LAFS): Start top to bottom, from inside moving outward, and moving away from HEPA filtered air. Use a clean sterile wiper for each surface (or the wiper-folding technique).
Sequence for Cleaning and disinfecting a horizontal LAFS
Vertical Laminar Air Flow Systems (LAFS): There are a couple different recognized solutions for cleaning a vertical LAFS. Each facility should check with governing regulatory agencies to see if a preferred process exists. Of these two recognized solutions, the 3rdstep differentiates these two processes (see examples below).
Option 1 is probably the most accepted process for vertical air flow especially for a biological safety cabinet (BSC) but it is also very commonly used for a Vertical Laminar Air Flow Workbench (LAFW).
Option 1 for Cleaning and disinfecting a vertical LAFS:
Ceiling starting back corner, moving side-to-side using overlapping strokes and moving outward to opening of PEC
Back wall staring in upper corner of PEC and moving downward away from HEPA filtered with side-to-side overlapping strokes (if bar is present, consider cleaning next)
Sides starting in upper corner and moving horizontally side-to-side with overlapping stokes
Work surface of the PEC staring in inner corner and moving side-to-side with overlapping strokes moving to the opening of the PEC
This technique offers the benefit of moving away from HEPA filtered air but does introduce movement from the opening of the PEC to the interior of the PEC. The sash of a BSC offers a barrier from the external environment making this a prefer technique however it is often used for vertical LAFW as well.
Option 2 for Cleaning and disinfecting a vertical LAFS:
Ceiling starting back corner, moving side-to-side using overlapping strokes and moving outward to opening of PEC
Back wall staring in upper corner of PEC and moving downward away from HEPA filtered with side-to-side overlapping strokes (if bar is present, consider cleaning next)
Sides starting in upper back corner and moving vertically downward to the DCA then lifting wiper and place at top of PEC (moving slightly towards opening of PEC, overlapping previous stroke) and repeat motions until entire side has been cleaned/disinfected (some will use the wiper-folding method here)
Work surface of the PEC staring in inner corner and moving side-to-side with overlapping strokes moving to the opening of the PEC
This technique offers the benefit of moving from internal spaces to the opening of the PEC but does introduce movement going back toward the HEPA filter (the wiper-folding method can be used here to reduce potential contamination near the HEPA filter).
It is important to establish a robust and well documented training program to establish consistency in cleaning and disinfection of the PEC throughout the facility. Ensuring the same routine is employed throughout helps mitigate potential contamination from being introduced into the PEC delivering safe and effective sterile compounded products.
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