Controlling both viable and non-viable contamination is essential to medical device performance and reliability. As the complexity of device design increases, so does the process of assuring that viable and non-viable contamination is controlled during manufacturing. Manufacturing process control is essential to achieve the appropriate surface quality, to achieve optimal functionality, and to achieve and maintain sterility.

We review sources of viable and non-viable contamination and the impact on product specifications for non-critical and critical devices. Non-critical devices contact intact patient skin (Figure 1). Critical devices come in contact with the bloodstream or with sterile areas of the body (Figure 2). We will also provide an update of current clean-room and controlled environmental standards. Given the variable complexity of device materials and of device assembly processes, many of these standards are normative by necessity. Understanding your product and the sources of contamination in your facility is essential to utilizing the standards effectively and for successful assembly or repair. In addition, while the impact of viable contamination has been emphasized primarily in medical and pharmaceutical applications, there is increasing realization that viable contamination can impact many critical products. One example is the potential of microbial contamination to induce corrosion.¹ Therefore, the potential impact of both viable and non-viable contamination on the product should be considered by most manufacturers, not only those involved in productionof medical devices.

VIABLE CONTAMINATION
Viable contamination may be defined as the presence of living microorganisms, which can be a collection of various types, including bacterial, fungi, algae, protozoa, and viruses. Although viruses are not considered living microorganisms, they are sometimes classified as microbes. Most viable organisms benefit humans; however, some species can cause infectious disease and, when introduced into the body, can produce strong toxins that can cause tissue degeneration. The microbes that cause these illnesses can sometimes be found in the manufacturing environment and include bacteria and fungi. The current methods of detection (sterility and bioburden testing) are capable of detecting most forms of bacteria and fungi. These tests can also detect the presence of sterilization-resistant microbes (Bacillus spores, Mycobacteria, and fungi) that might be problematicin the terminal sterilization process.

THE CLEANING PROCESS – STERILIZING VS. CLEANING
Sterilizing and disinfection are not the same as cleaning. A device may be sterile. A sterile device may be left in an airtight container and remain sterile for years, perhaps decades. However, if the device is not clean,it can still negatively impact the host.