Medical devices are a vital part of the global healthcare system that can have far-reaching impact on patient treatment. Therefore, they must be sterile to ensure the patient safety. The prevalent microorganism′s type on a medical device, also known as ′bioburden&rdquo′, is a useful indicator of a potential contamination source. Indeed, bioburden is a potential risk to the patient not only because the sterilization process might not be completely effective, but also post-processing because of the possible presence of residual materials. Although bioburden may be confidently killed by destructive sterilization processes, its proliferation before sterilization should be avoided. For the bioburden determination, culture media and incubation conditions must be carefully selected. Culture media is of fundamental importance for most microbiological tests: to obtain pure cultures, to grow and count microbial cells, and to cultivate and select microorganisms. A culture medium is essentially composed of basic elements (water, nutrients), to which must be added different growth factors that will be specific to each bacterium and necessary for their growth. Without high-quality media, the possibility of achieving accurate, reproducible, and repeatable microbiological test results is reduced. In the ISO 11737-1 (2018) ′Sterilization of health care products- Microbiological methods- Part 1: determination of a population of microorganisms on products′, methods for the determination and microbial characterization of bioburden are proposed. However, few guidelines are given as to culture media other than examples and incubation times. Several studies show that other culture media can also be effective, such as Plate count Agar (PCA). The purpose of this review was to focus on parameters which can have an impact on the bioburden evaluation, specifically the culture media type for the microorganism′s detection in medical devices. Experimentations conducted in our laboratories showed that Plate Count Agar appeared to be a medium of primary importance for the detection of bioburden on medical devices, this media also respecting the 3R9s rule.

Pulsed light (PL) is a non-thermal technology which leads to different applications (food, pharmaceutical and cosmetic packaging, medical devices) by inactivating microorganisms, knowing that the properties of PL technology are cumulative treatment, especially for bacteria. PL uses intense flashes of white light (200 nm–1100 nm wavelengths), rich in UV (200 nm–400 nm) and produced by xenon flash lamps. Localized photothermal and photophysical effects, but also the capability of its UV light component to modify the structure of biomolecules (photochemical effect), such as DNA and proteins, are the main mechanisms involved to explain the inactivation of microorganisms by PL. As compared to other sterilization methods, such as heat or chemical disinfectant treatment, PL treatment has several advantages; it is faster, induces low operational cost and leaves no residues. Nevertheless, no exhaustive data on exposure conditions are available, which would make it possible to repeat, interpret and evaluate the data needed for large-scale industrial deployment of PL in pharmaceutical and cosmetic packaging and medical devices. Research should also focus on understanding the inactivation mechanisms of different bacterial strains, states, and morphologies when exposed to PL.

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 gloves9 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.