Endospores in Autoclave Sterilization Efficacy: What to Know

In the medical or industrial field, you will come across autoclaves. These are steam sterilizers that use steam under pressure to eliminate harmful bacteria, viruses, fungi, and spores. The items placed in the autoclave are heated to an appropriate sterilization temperature for a specific period. In turn, the moisture in the steam transfers heat to the items to eliminate the protein structure of the spores and bacteria.

How to Test the Effectiveness of Autoclave Sterilization

To test the effectiveness of the autoclave machine, one of the best ways to do this is by using endospores. Let’s dive deeper into it to help you fully grasp its concept.

Endospores are hard to kill because it’s a different kind of bacteria. Different temperatures are used to kill it, which is why it can be used to calibrate autoclave temperatures. Due to its nature, it’s easy to store in the lab until it’s needed. In addition to that, they are simple structures that are easy to detect and they’re composed of all the molecules found in living cells.

Due to their resistance to heat, spores are used to measure the biological performance of the autoclave process.

The testing process involves at least two spore ampules used per cycle. The spore ampoules must be placed in a horizontal position inside a Biohazardous bag with items to be sterilized.

You need to choose the right cycle to process the spores and items inside the bag. Once the cycle is complete, the autoclave must be allowed to decompress and cool down—a minimum of ten minutes. Once the machine has cooled down, retrieve the spores from the load.

After this, the spores need to undergo an incubation period wherein an adjusted microbiological incubator must be used.

There are other indicators to test the efficacy of the autoclave process:

  • Physical: The use of pressure and temperature recording devices.
  • Chemical: The use of indicators that change in color after being exposed to specific temperatures.

What are Endospores

To fully grasp the concept of using endospores to test the effectiveness of an autoclave, you need to understand what endospores are.

An endospore is a dormant and non-reproductive structure that is produced from the bacteria Firmicute phylum. Its formation is triggered by a lack of nutrients and typically occurs in Gram-positive bacteria. Endospores enable bacteria to lie dormant for long periods, which can even last for centuries.

When the environment is favorable, the endospore can reactivate itself to the vegetative state. Therefore, autoclave sterilizers use endospores to test their effectiveness. Since it’s difficult to kill, if it can kill this tough structure, then rest assured that it can destroy all other types of bacteria that can contaminate medical and industrial tools.

How an Autoclave Works

Now that you know how endospores are used to test the effectiveness of autoclave machines, it’s time to know how it works. Knowing the process will help you better comprehend how it can sterilize essential tools in healthcare or industrial facilities.

Items are placed inside the pressure vessel, also referred to as the chamber. To ensure successful steam, there are three sterilization factors that are considered: time, temperature, and the quality of the steam.

To meet all of these factors, the autoclave process undergoes three phrases:

Conditioning Phase

During the first phase of sterilization, the air must be removed from the chamber. This cycle is called conditioning. There are two types of air removal-type steam that can be used here:

  • Dynamic: The air can be removed from the chamber through a vacuum system. However, it can also be removed without the vacuum system through a series of steam flushes and pressure pulses.
  • Gravity: This uses steam to eliminate the air in the chamber and force it down the sterilizer drain.

Exposure Phase

Once the air is removed, the drain of the machine will close and steam will be admitted into the chamber. The steam will quickly increase the pressure and temperature inside to a predetermined level. When this happens, it enters the exposure phase and items will be held at the sterilization temperature for a fixed amount of time.

Exhaust Phase

The final phase of the cycle is the exhaust phase, in which the sterilizer drain is opened and the steam removed. In turn, this depressurizes the vessel and allows the items inside to dry.

For successful autoclave sterilization, quality steam is important. The steam must be composed of 97% steam and 3% moisture.

Testing the efficacy of autoclave requires proper labeling, especially for the spores that need to be used. With that, you need to get a specialized label for that. Labeling is extremely important here to ensure the safety of everyone in the facility. Moreover, all test results must be recorded in your autoclave log form. Finally, ensure proper disposal of all spores used, and that includes autoclaving them before throwing them away.

The autoclave sterilization process follows a basic principle in which each item must be exposed to direct steam contact at a specific and necessary temperature and pressure for a particular time period.

Like all the other sterilization systems, the steam cycle must be monitored by mechanical, chemical, and biological monitors. Typically, steam sterilizers are monitored using a printout by measuring temperature, the time at the temperature, and pressure.

Steam sterilization must be used on all critical and semi-critical items that are heat and moisture resistant, such as anesthesia equipment and steam sterilizable respirator therapy tools. Moreover, autoclave sterilization is used in healthcare facilities to decontaminate microbiological waste and sharps containers.

Label Them Right

Here at Nev Ink, we sell autoclave tapes that are used to determine items that have gone through the sterilization process. Once the taped items have passed through the sterilization process, the ink is activated and changes colors. Usually, this is used with an autoclave wrap. Our autoclave tapes are lead-free, and they come in various sizes you can choose from. Shop now for the best-quality autoclave tapes. We also have other tapes for various applications.

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