USP 797: Microcleaning and the controlled environment-Part 1

06/01/2005

Douglas Theobald continues his series on USP 797 with this two-part look at microcleaning

by Douglas Theobald, CFM

Microcleaning is the process whereby the surfaces in a controlled environment are disinfected and sanitized with the elimination of microscopic-scale contaminants as the core objective. In USP general chapter 797, we are given a list of “Suggested Standard Operating Procedures” as a guideline, wherein there is mention of cleaning and sanitization of work surfaces and laminar airflow workstations (LAFWs) and “the direct compounding area.” At this juncture, I would like to add to or, rather, expand the list of recommendations to include procedures for microcleaning the entirety of the controlled environment. Previously, I have made reference to the potential for cross-contamination either by personnel, materials and equipment-and even airflow-within the controlled environment. If our focus remains only on the immediate surroundings of the operator or technician, we neglect a large piece of real estate that is the controlled environment.

Things unseen

A very practical application of detailed cleaning techniques can result in an environment of highly maintainable integrity. The use of a standard operating procedure that clearly defines the purpose, process and equipment utilized for microcleaning the controlled environment is critical. The term microcleaning directs us to a level of maintenance that is far beyond general housekeeping. Our goal is to remove the contamination that inherently exists although it is not visible to the naked eye. Typically particulate contamination 35 to 40 μm or larger in size can be seen with a visual inspection. When our goal is to clean at that level, we are dealing with what is termed “gross contamination.” At best, this kind of cleaning is performed as a precursor to microcleaning, usually after moving equipment, installing new equipment or performing maintenance or construction in the controlled environment or on major components such as air handling units, fluid or gaseous delivery systems, etc. Remembering how the revisions to the USP practices came about (contamination of compound sterile preparations [CSPs] on a biological level), we understand the need to remove particulate contamination at the level of .5 and .3 μm as well as identify and remediate bioburden.

Assuming that we have followed recommendations during the construction of the cleanroom and used nonporous, smooth, washable surfaces (including the floors, walls and ceilings), we can address the actual cleaning of various elements of the room. There are some standard practices for the mechanical aspects of cleaning as well as procedures for use and application of disinfecting and sanitizing agents. We’ll break it down from here.

Get in position

The first thing to determine is whether to generate standard operating procedures and forms using “in-house” resources or by outsourcing the task. It will be necessary to determine who will be performing the physical task of microcleaning. The standard janitorial company or janitor is not certified to work in or maintain a controlled environment. If you determine to use an outside company, verify the training and certification to perform work in a cleanroom; do not just take their word for it. Either way, the following information will be, I hope, of great assistance. The standard operating procedure will delineate not only the purpose but the procedure or process and equipment that will be utilized to perform the microcleaning. We know the purpose, but when determining the procedure, here are a few things we need to consider. First, make sure you understand the physical configuration of the room, including the activities that are occurring on a regular basis as well as the flow of product. The more critical the process, the more detailed the cleaning should be in that area.

Risk = Frequency

USP 797 addresses high-, medium- and low-risk activities; we can use that as a basis for the frequency of the cleaning to be performed. The more critical the area, the more frequent the cleaning. While we are instructed that the operator or technician should clean the immediate work area before each shift and when changing from one operation to another, under the section entitled “Cleaning and Sanitizing the Workspaces,” we are told that “floors in the buffer or clean area are cleaned by mopping once daily when no aseptic operations are in progress.” This includes the use of a cleanroom-approved, nonshedding (dedicated) mop and an approved cleaning agent. In fact, the equipment used for cleaning the controlled environment should be dedicated to (and preferably stored in) that environment.

Using the system

A systematic approach to cleaning is the most effective approach. Since we are cleaning contamination that cannot be seen with the eye, it is important to assure that we address the entire surface being cleaned. The only way to achieve this is through method. The cleaning should start in the most critical area and move to the least critical area. Typically, this means starting in the cleanroom and cleaning towards the anteroom. At no time should one go back over an area previously cleaned in order to gain access to another area.

In the case of a “full” cleaning, we address the ceiling first, followed by the walls, work surfaces, shelving, window sills, door hardware, etc., and finally the floor. Using a cleanroom-approved sponge mop while cleaning a surface, the mechanical action should move in the same direction with each stroke (never mop or wipe in circular or scrubbing motions as this tends to reintroduce contamination over previously cleaned surfaces). For ceilings, the strokes should generally be about four feet in length and straight; each stroke overlapping the previous a minimum of about 10 percent (the same is true for floors). When cleaning walls, the strokes should begin at the top and end at the bottom if possible. It is best to rinse and resaturate the mop every two to four strokes, having turned the mop over for each stroke. When cleaning work surfaces, the cleaning action should be straight strokes from back to front, overlapping as before. It is a good practice to use a nonlinting cleanroom wipe folded in quarters, changing sides with each stroke. Industry standard specifies that the wipe be either a presaturated wipe or a dry wipe with the cleaning agent applied to the wipe (not the surface) with a spray bottle. For general disinfecting, isopropyl alcohol is a basic standard. It also works very well as a follow-up wipe to clean up any residue from many of the germicidal or detergent cleaners. Of course, if you can see visible soiling on the surface of a wipe or mop, it is past time to change the wipe, rinse the mop or change the cleaning solution.

The caveat

At this point, I want to reiterate that the information here is cursory. There is more to it and there are definitely variations. My attempt is to provide some basic information to assist in the movement towards better understanding of the standards and hopefully facilitate a low-pain approach to compliance. Please feel free to contact me with questions and comments. Next time, I will provide an in-depth review of cleaning solutions, their preparation and purpose, and how to use them. III

Douglas Theobald is a consultant and general manager with Controlled Contamination Services LLC (San Clemente, Calif.). He can be reached at [email protected].