Can you imagine learning that the surgical instruments used in your recent medical procedure were contaminated? What a frightening prospect! That is why vigilance around maintaining appropriate levels of sterilization control is so critically important.
The world is full of microorganisms that can pose a variety of health-related threats to society. To help protect us, various forms of sterilization are used across industries to help reduce, if not eliminate, our exposure to these hazards. The Food and Drug Administration specifically mandates the use of sterilization in the food and medical products industries through the Code of Federal Regulation, Part 820 Quality System Regulation. These mandates require the validation of the sterilization process and verification that confirms the sterilization has been successfully fulfilled.3
The formal definition of sterilization is “the process of destroying all microorganisms and their pathogenic products.”4 The aim of sterilization is the reduction of bioburden (microorganisms or potential pathogens) that could lead to illness and infection as the result of contact with these pathogens on the products we encounter - whether they are food, medicine or medical instruments.
The sterilization process can be accomplished through a variety of means such as heat, radiation and the use of chemicals.5 The following lists the various options available today, describing the process, features and caveats.
Each of the radiation sterilization methods noted above has its limitations, so choosing the correct method will help ensure the validation of the sterilization as mandated by governing agencies.
Sterilization procedures should be monitored through a combination of mechanical, chemical and biological techniques designed to evaluate the sterilizing conditions and the procedure's effectiveness.12
The Center for Disease Control requires that any load containing implantable devices be monitored, and that each sterilizer be tested at least weekly through the use of BIs to verify the units are functioning correctly.15
Once the sterilization cycle has been completed, the load should be protected and handled in a way that will maintain the sterility of the product.16 In addition, manufacturer’s instructions on proper installation and equipment maintenance should be followed for all sterilization equipment.17
The location of microorganisms on a product is a critical factor that must be assessed to ensure that the appropriate sterilization method is being used. Medical instruments with multiple pieces must be disassembled and equipment such as endoscopes that have crevices, joints and channels are more difficult to access than are flat-surface equipment. This is because it is difficult for the sterilization process to penetrate all parts of the equipment. Only surfaces that directly contact the sterilant will actually be sterilized, so there must be no air pockets and the equipment must be completely immersed for the entire exposure period. Given this challenge, manufacturers should be encouraged to produce equipment that is easy to sterilize and clean.18
Once the sterilization process is completed, it must be verified. This verification is conducted through the use of a mathematical process called Sterility Assurance Level (SAL) to determine the probability that a given process has made something sterile. A level of 10−6 is recommended for organisms on a sterilized device.19 This is essentially saying that there is a less than or equal to one chance in a million that an item remains contaminated and is therefore not sterile.20
There are numerous firms globally that provide contract sterilization services. Two of the largest and most recognized names in the contract sterilization business are Steris and Sterigenics International, Inc. Contract sterilizers should be compliant with the FDA’s 21 CFR 820 for quality systems along with ISO 13485. They should also be in compliance with various standards (ANSI, AAMI and ISO) governing sterilization methods as noted:
Any companies using contract sterilization firms should implement the practice of formal contracts with a statement outlining the role and responsibility of both parties. These contracts should have legal review and include insurance requirements as a means of providing financial protections to the manufacturer. The collection and retention of sterility certificates is also important in tracking products for recall purposes once it is released to the market. The ability to retrieve products that are believed to be contaminated is critical in protecting the end user from possible injury or illness.
There will always be a need for sterilization to protect the public from harmful microorganisms. Ensuring sterilization procedures are properly implemented and verifiable is also critical as many of the sterilization processes are themselves potentially harmful, not only to the end product but to those working with the various sterilization techniques. The total elimination of harmful microorganisms is simply not possible. However, the science and technologies used to measure the success of sterilization techniques, along with the governing regulatory requirements, have created a system that, has served well in protecting the public from unseen harm.
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1 Mundell, E. J. (June 16, 2009). “VA faces questions over tainted colonoscopies.” US News. Retrieved April 2014. http://health.usnews.com/health-news/family-health/cancer/articles/2009/06/16/va-faces-questions-over-tainted-colonoscopies
2 Associated Press (February 11, 2014). “20 exposed to incurable brain disease in N.C. hospital” Retrieved April 2014. http://www.usatoday.com/story/news/nation/2014/02/11/creutzfeldt-jakob-exposure/5389547/
3 USFDA, CFR 21, Part 820 Quality System Regulation. Retrieved February 2014. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=820&showFR=1&subpartNode=21:184.108.40.206.12.2
4 The Free Dictionary, Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. Retrieved February 2014. http://medical-dictionary.thefreedictionary.com/sterilization
5 The International Pharmacopoeia, Fourth Edition, 3rd Supplement, 2013, Section 5.8 – Methods of Sterilization. Retrieved February 2014. http://apps.who.int/phint/en/p/docf/
6 CDC, Guidelines for Disinfection and Sterilization in Health Care Facilities, 2008. Retrieved February 2014. http://www.cdc.gov/hicpac/disinfection_sterilization/7_0formaldehyde.html
7 How is Radiation used to sterilize medical instruments? Health Physics Society. Retrieved February 2014. http://hps.org/publicinformation/ate/q4004.html
8 “Gamma Processing.” Synergy Health. Retrieved February 2014. http://www.synergyhealthplc.com/sites/default/files/synergy-health-sterilisation-specialist.pdf
9 “X-Ray Sterilization of Medical Devices.” MedicalDevice-Network.com. Retrieved February 2014. http://www.medicaldevice-network.com/projects/x-ray-sterilization/
10 Image of Ionization Sterilization and penetration distances. http://en.wikipedia.org/wiki/Sterilization_(microbiology)
11 Ultraviolet germicidal irradiation http://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation
12 CDC, FAQ on Sterilization-Monitoring. Retrieved February 2014. http://www.cdc.gov/OralHealth/infectioncontrol/faq/sterilization_monitoring.htm#a1
13 Ibid 12
14 Ibid 12
15 Ibid 12
16 “The Standard for Cleaning, Disinfection and Sterilization of Reusable Medical Devices for Health Care Facilities and Settings.” (June 2012). Alberta Government. Retrieved February 2014. Section 7.4, page 20. http://www.health.alberta.ca/documents/IPC-Medical-Device-Cleaning-2012.pdf
17 Ibid 16, page 21.
18 Rutala, William; Weber, David (November 2008). “CDC Guideline for Disinfection and Sterilization in Healthcare Facilities.” Retrieved February 2014 http://www.cdc.gov/hicpac/Disinfection_Sterilization/4_0efficacyDS.html
19 Ibid 4
20 “Sterility Assurance Compliance- A Guide for Medical Device Manufactures.” Northview Biosciences, Inc. Retrieved February 2014. http://hbehcan.tripod.com/dosyalar/mak.pdf
21 “Sterility Assurance Levels (SAL).” Steris Isomedix. (September 2007), Retrieved February 2014. http://www.isomedix.com/wp-content/uploads/2013/03/19-Sterility-Assurance-Levels-SALs-Irradiation.pdf