Updated: Apr 19
Editorial | Open Access | Published 18th April 2023
GUEST EDITORIAL : The Fallacy of Sterile Gowns
Author : Russell E. Madsen*
Sterilized gowns are commonly used in pharmaceutical aseptic processing areas. Great care is taken during the gowning process to ensure the exterior surfaces of the gown remain sterile; however, studies have shown that this is unlikely to occur. Commercially laundered, non-sterilized gowns have been shown to contain few if any microorganisms prior to gowning. The use of non-sterilized commercially laundered gowns for aseptic operations does not jeopardize product quality, reduces costs and saves energy.
Key words: aseptic gowning, aseptic processing, sterile gowns, pharmaceutical clean rooms
It is common practice in the pharmaceutical industry to use sterilized gowns in aseptic processing areas. Great care is taken to keep the exterior surfaces of the gown sterile during the gowning procedure and throughout its use. However, observation of the gowning process and various studies confirm that microbes shed by personnel during the gowning process render gown surfaces non-sterile as soon as the gowns are put on. A better approach might be to use commercially laundered, non-sterilized gowns for aseptic processing operations. Surprisingly, such gowns have been shown to contain few if any viable microorganisms prior to donning. Switching to non-sterilized gowns would not jeopardize aseptic operations, would reduce costs and save energy, making this a win-win-win option to the use of sterilized gowns.
People are the primary source of microbial contamination in pharmaceutical cleanrooms (1). Fully gowned operators (suit, hood, boots, and gloves) emit about 17,000 particles per minute (2). It is obvious that many of these particles are microorganisms that are detectable as colony forming units (CFU) in the cleanroom environment and on the surfaces of the operators’ gowns.
No matter how carefully gowns are put on, studies have shown that their exterior surfaces collect microorganisms (3). Also, bacteria may penetrate through the clothing system material and contaminate the outer surfaces of the cleanroom garments (4). Whyte and Eaton have shown that cleanroom garments transfer microorganisms to hard surfaces with a mean transfer coefficient of 0.6, i.e., microorganisms present versus those transferred to the surface (5). Satter et al. have developed a quantitative model for the transfer of bacteria from fabrics to hands and other fabrics (6).
Commercially laundered cleanroom garments washed in water at 75 °C for six minutes before drying in HEPA-filtered air prior to packaging in individual heat-sealed polybags have been shown to contain very few, if any, viable microorganisms prior to donning (7). Immediately following a careful and controlled gowning process, these gowns were tested with contact plates at multiple locations. Positives were observed in all areas tested. Thus, the microbiological quality of the gown had been degraded by the gowning process, leading to the question as to why sterilized cleanroom garments are required in the first place.
Non-sterilized, commercially laundered cleanroom clothing offers significant advantages over sterilized cleanroom clothing in terms of cost and environmental impact without adversely affecting the quality of aseptically produced pharmaceutical and biopharmaceutical products; it is known from controlled studies that the exterior surfaces of worn cleanroom clothing contain microorganisms even if such clothing was sterile to begin with. Furthermore, studies have demonstrated that commercially laundered cleanroom clothing can have vanishingly small numbers of microorganisms prior to use.
Conflict of Interest Declaration
The author declares no conflict of interest.
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02. Strauss L, Larkin J and Zhang KM. The use of occupancy as a surrogate for particle concentrations in recirculating, zoned cleanrooms. Energy and Buildings 2011;43(11):3258-62.
03. Smith L, O’ Driscoll N and Lamb A. A comparison of the bacterial contamination of the surface of cleanroom operators’ garments following donning with and without gloves. European Journal of Parenteral and Pharmaceutical Sciences 2021;26(3):263-80.
04. Grangé J, Nguyen S, Bordenave J, et al. Contamination of integral protective suits in the sterile environment used for producing total parenteral nutrition bags. Le Pharmacien Hospitalier 2011;46(1):e12-18.
05. Whyte W and Eaton T. Microbial transfer by surface contact in cleanrooms. European Journal of Parenteral and Pharmaceutical Sciences 2015;20(4):127-31.
06. Sattar SA, Springthorpe S, Mani S, et al. Transfer of bacteria from fabrics to hands and other fabrics: development and application of a quantitative method using Staphylococcus aureus as a model. Journal of Applied Microbiology 2001;90(6):962-70.
07. Smith L. A comparison of the bacterial contamination of the surface of cleanroom operators’ garments. EJPPS 2021;26(3):263-80.
*Corresponding author: Russell E. Madsen, 18907 Lindenhouse Road, Gaithersburg, MD 20879; Telephone: 1-301-938-4266; email: firstname.lastname@example.org
Russell E. Madsen holds a Bachelor of Science degree from St. Lawrence University and a
Master of Science degree from Rensselaer Polytechnic Institute. He was President of The
Williamsburg Group, LLC, a consulting firm located in Gaithersburg, Maryland. Prior to forming
The Williamsburg Group, he had served PDA as Acting President and was Senior VP Science and
Technology. Before joining PDA, he was employed by Bristol-Myers Squibb Company as
Director, Technical Services, providing technical and general consulting services to Bristol-
Myers Squibb operations, worldwide. He is a member of the Executive Committee of ASTM
Committee E55 on Manufacture of Pharmaceutical and Biopharmaceutical Products, an
Honorary Member of PDA and past Board member of that organization. He has authored or coauthored
over 90 publications.