What’s the Difference Between Sterile and Aseptic?

The terms “aseptic” and “sterile” are often used interchangeably. They both refer to a similar objective—eliminating/reducing potentially harmful microorganisms, but the differences are crucial in cleanroom and pharmaceutical environments, as well as related spaces involving the processing of sensitive materials. While both are commonly used contamination-control techniques, they are, in fact, different concepts.

What is aseptic processing in pharmaceuticals? What does non-sterile mean? Keep reading for the answers to these and other important questions.

Aseptic vs. Sterile

Any cleanroom staff must understand the key distinctions between the two. The industry-recognized definitions of each are as follows:

• Aseptic: A surface, object, product, or environment has been treated such that it is free of contamination. Bacteria, viruses, or other harmful living organisms cannot survive or reproduce. Aseptic processing doesn’t create a sterile condition; it only maintains sterility.
• Sterile: A product that is completely free of microscopic organisms. While sterile means the complete absence of bacteria, viruses, and fungi along with spores, it doesn’t distinguish between specific pathogens. A sterilization technique aims to rid an environment of all living microorganisms.

Sanitize vs. Sterilize

Sanitation is a related concept that often arises in these discussions. For that reason, it’s worth touching briefly on the differences between sanitation and sterilization.

Sanitizing aims to reduce the number of microorganisms to safe levels as defined by public health standards, typically through the use of chemicals or heat. Sterilizing, as previously noted, seeks to completely eliminate all forms of microorganisms, including spores. This is done through more intensive methods that can include autoclaving, chemical sterilants, or radiation. The process is essential in medical and laboratory settings.

So what’s the difference between sanitization and aseptic processing? It has to do with their scope and application. While sanitizing merely reduces microbial load, aseptic compounding techniques can be used to assist in maintaining an environment free from pathogens, which is vital for procedures and processes where contamination must be prevented, such as pharmaceutical manufacturing.

How Does Each Process Differ?

Sterilization is a radical process that can be achieved in various ways. It is often used in medical environments, for example, to clean surgical instruments.

Isopropyl alcohol is a common localized disinfectant. For sterilizing large areas, hydrogen peroxide or peracetic acid droplet foggers may be used. Devices are often sterilized with autoclaves or gamma radiation.

Asepsis is important for cleanrooms where people work because humans are effective transporters of microbes. It does not guarantee full sterility. Nonetheless, it promotes a sterile environment by incorporating measures such as established cleanroom practices, training, and wearing gowns and other protective gear.

In short, sterilization is the process of eliminating harmful microorganisms; asepsis is the key objective of any ISO-certified cleanroom facility.

What Is the Difference Between Sterilizer and Disinfectant?

A sterilant, whether a liquid or vapor, destroys all microbial life it comes in contact with. An antiseptic destroys or inhibits the activity of microbes on living tissue, while a disinfectant does so on inanimate objects, although spores may survive.

Under Which Context Would Each Condition Be Necessary?

Aseptic is used in the context of cleanroom operating procedures. In addition to wearing gowns, it is also applied to the requirements of having personal protective clothing. Gloves, masks, hoods, goggles, aprons, and lab coats fall under this category.

The standard operating procedures of a cleanroom essentially dictate the facility’s aseptic approach. These often include guidelines such as:

• When to change protective clothing
• In what order to don and remove such items
• Test tools and equipment used on cleanroom staff after wearing protective items
• Hand washing
• Removal of watches and jewelry
• Visual inspection of work areas
• Frequency of sanitization
• Use of solutions with at least 70% alcohol

In addition, aseptic conditions are also maintained in areas where achieving complete sterilization is unlikely, such as a hospital or physician’s waiting room.

Where Sterile Conditions Are a Must

Cleanrooms are generally not completely free of microbes. This is true even when contaminant-reducing procedures, such as aseptic gowning for the cleanroom, are carefully followed. The greater concern is with controlling airborne particles. Nonetheless, HEPA filters are capable of capturing a variety of microbes.

Sterility, under the definition described above, is even more important in operating rooms where any level of microbes can infect an open wound. A range of pharmaceutical products must be sterile as well. These range from syringes to ophthalmic formulations, to hemodialysis solutions and sterile medicines.

Similarly, the biotechnology industry—which often uses cleanrooms—relies on sterile processes for the production of vaccines, gene therapies, and other biologics to ensure product safety and efficacy. The microelectronics industry also demands high levels of sterility and particle control to avoid defects in semiconductor manufacturing.

In addition, the food and beverage industry often requires a sterile work environment during certain processes, such as aseptic packaging, to prevent contamination and extend shelf life.

Across these industries, various sterilization methods—such as steam sterilization, ethylene oxide gas, and gamma irradiation—are employed to achieve and maintain sterility.

What Is a Sterility Assurance Level?

A sterility assurance level (SAL) is used in multiple industries to measure the effectiveness of a sterilization process—for instance, treating sterile cleanroom apparel. It is a statistical measure of the probability of an object being non-sterile after it has undergone a sterilization process. The standard level is 10^-6, meaning sterile processing has resulted in less than or equal to a one in one million chance of a viable microorganism surviving.

The various sterility assurance levels are as follows:

• 10^-1: 1 in 10 probability of a viable microorganism surviving
• 10^-2: 1 in 100 probability of a viable microorganism surviving
• 10^-3: 1 in 1,000 probability of a viable microorganism surviving
• 10^-4: 1 in 10,000 probability of a viable microorganism surviving
• 10^-5: 1 in 100,000 probability of a viable microorganism surviving
• 10^-6: 1 in 1,000,000 probability of a viable microorganism surviving (standard level for healthcare and pharmaceutical sterilization)

These levels indicate the relative strictness of the sterilization process, with SAL 10^-6 being the most sterile

How Both Pertain to Sanitization

The relationship between aseptic and sterile is a close one despite the differences in definitions. In regard to sanitization, both must be considered during the following steps:

• Inspection: If a surface or item comes in contact with a contaminated object, it must be immediately sanitized to eliminate hazards. All personnel hired to work in a cleanroom must be trained to identify these and ensure the space is free of trash, debris, or contaminated products or equipment.
• Cleaning: Cleanroom surfaces must be cleaned daily, and the cleaning process should be documented in clear detail to ensure proper procedures, such as aseptic compounding techniques, are correctly followed. To ensure your team is following all applicable standards, maintain logs of when it was sterilized and how and what was used to disinfect the cleanroom.
• Disposal: Aseptic processes aimed at achieving a safe environment can include proper disposal of materials, immediate wipe-up of any spillage, and re-sanitization of personnel who have left the sterile area and returned to it.

Contact Prudential Cleanroom Services at Prudential Overall Supply

We provide nationally recognized laundry and cleanroom apparel services for pharmaceutical, medical device, aerospace, semiconductor, and other companies. Operating throughout the United States, our business also sells protective clothing, personal protective equipment, and facility supplies. Prudential Cleanroom Services at Prudential Overall Supply provides uniform rental and lease services as well as needs assessments.

Whether you need reliable laundry services or just a supplier of sterile cleanroom goggles, Prudential is the resource you can trust. Call 800-767-5536 for more information.