Microbial contamination and isolator gloves: if it all came down to the size of a hole?

Abstract

Isolators play a critical role in protecting both the product and the environment, as well as the personnel involved in pharmaceutical manufacturing, analytical procedures and sterility testing. Gloves attached to the windows and doors of the isolator are designed to facilitate intervention, testing and safety. However, due to their inherent characteristics and vulnerability to puncture or loss of integrity, they are recognised as a significant potential source of contamination. In addition to the possible pathways of contamination transfer, the size of glove holes plays a critical role in determining the risk of contamination. In this study, chlorosulphonated polyethylene (CSM) gloves were exposed to an aerosol containing Bacillus subtilis or Staphylococcus aureus. This assessment aimed to ascertain the integrity of the gloves' seal. It was postulated that, below a certain aperture size, gloves used in isolator systems could establish an effective seal, even if the external surface of the gloves exhibited modifications. Calibrated holes of different diameters (0.3, 0.5, 1, 1.5 mm) were created using a femtosecond laser drilling technology. The holes were located on the tip of the middle finger. Based on the context of our study, passage of micro-organisms through glove holes of a certain size does occur. Under the experimental conditions chosen, the cut-off for passage was determined to be a 0.5 mm hole, regardless of the micro-organism evaluated. Although this study has some limitations, including the lack of a panel of micro-organisms evaluated and the investigation of a single glove type called CSM, the high level of "worst case" challenge conditions provides compelling data to support our results. It would now be interesting to carry out studies at different production sites to assess their risk of contamination and relate this to their glove failure.