Evaluation of the MicroWorks, Inc. Swab Sampling System (MSSS™) for Use in Performing Quantitative Swab Sampling

Abstract

The purpose of this study was to qualify the MicroWorks, Inc. Swab Sampling System (MSSS™) swab kit for use in sampling cleanroom surfaces for bioburden. A six-part study was performed to demonstrate the suitability of the swab materials, the recovery of bioburden from typical cleanroom surfaces, the neutralization of typical disinfectants used in cleanrooms, the removal of diluents from the swabbed surface, and the hold time for test samples. A total of 13 challenge organisms were used: six National Collection of Type Cultures/American Type Culture Collection (NCTC/ATCC) standard culture organisms and seven environmental isolates, which were recovered from different MedImmune manufacturing facilities.

Based on the results of the study it was shown that 12 of the challenge organisms were recovered from the calcium alginate swab materials and 13 of the challenge organisms were recovered from the sodium citrate diluent at ≥70%. Eleven organisms, including the six NCTC/ATCC organisms and five of the environmental organisms, were recovered from stainless steel, glass, polyvinylchloride curtain material, latex glove material, and neoprene at a rate of ≥70%. Effective neutralization was shown for LpH (an acid phenolic compound manufactured by Steris Corporation, Mentor, OH), Vesphene II, Spor-Klenz, 70% isopropyl alcohol (IPA), and Biocides B, X, and Y when utilizing the filtration/rinsing process. Recovery of six NCTC/ATCC organisms was demonstrated at ≥70%. The study also demonstrated that the diluents could easily be removed from the swabbed surface by following the swab with a 70% IPA wipe. A hold time of at least 24 h was demonstrated when samples were stored at 2–8 °C.

The results of this study demonstrated that the MSSS™ swab kit and qualified test method recover ≥70% of surface bioburden from common cleanroom surfaces in the presence of a wide variety of disinfectants.