Evolution in Disinfection and Sterilization: Is Now the Right Time to Reassess the Standards Used to Measure Medical Device Processing?

It’s been almost 65 years since Dr. Earle Spaulding formulated a risk-based system – the Spaulding Classification – to determine the minimal degree of safe processing required before a medical/surgical device could be (re-)used according to its intended use [1]. With many options for processing, and not all medical devices having the same degree of risk involved in their use [2], it is a valuable aide to professionals who must ensure medical devices are at a hygiene level suitable for their relevant application to ensure patient safety [1].

The Spaulding Classification has been widely adopted by infection control professionals, as well as in the formulation of various global regulations and clinical standards [1][3][4]. While its concept remains valid, unexpected processing failures suggest a need for reconsideration and potential optimization [1]. Furthermore, as the U.S. Food and Drug Administration (FDA) already noted in 2015, the Spaulding Classification fails to address all clinical device uses and all processing needs [3].


Dr Earle Spaulding, a professor and Chairman of the Department of Microbiology and Immunology at Temple University School of Medicine and Hospital [5], proposed "a strategy for sterilization or disinfection of inanimate objects and surfaces based on the degree of risk involved in their use" [6]. His three-tier system divided patient care devices into three categories: non-critical, semi-critical, and critical (Table A), and identified corresponding levels of microbiocidal activity: sterilization, high-level disinfection, intermediate-level and low-level disinfection for strategies within the three categories. Classification leads to decisions on the level of disinfection or sterilization required for medical/surgical devices (see Table B).

Table A: Spaulding Classification

Critical devices

Semi-critical devices

Non-critical devices


Critical devices are devices introduced directly into the bloodstream, or that would contact a normally sterile tissue or body-space in use [3].

Semi-critical devices contact intact mucous membranes or non-intact skin. They typically don’t penetrate tissues or enter normally sterile areas of the body [3].

Non-critical devices are instruments and other devices whose surfaces contact only intact skin and don’t penetrate [3].


Surgical instruments

Endoscopes used in sterile body cavities such as Laparoscopes, Arthroscopes, Intravascular endoscopes

Endoscope therapeutic accessories [3]


Endotracheal tubes


Laryngoscope blades and other respiratory equipment [3]

Blood pressure cuffs


Skin electrodes [3]

Required process




Table B: Sterilization vs disinfection



Critical items (will enter tissue or vascular system or blood will flow through them) [7]

High-level (semi-critical items; [except dental] will come in contact with mucous membrane or non-intact skin) [7]

Intermediate-level (some semi-critical items and non-critical items) [7]

Low-level (non-critical items; will come in contact with intact skin) [7]

An evolution

Since the Spaulding classification was published the complexity of medical interventions and the degree of non- or minimally invasive therapeutic treatment has significantly evolved.

Treatments like Endoscopic Retrograde Cholangiopancreatography (ERCP) were introduced in the 1970s, using endoscopes and fluoroscopy to take images to aid patient diagnosis and treatment. Interventional pulmonology using convex probe endobronchial ultrasound technology, and minimally invasive surgery such as laparoscopy followed by the 2000s. However, with this rapid progress came the potential for infections as the medical procedures were increasingly complex [10].

Other contributing factors included the use of more advanced medical instruments with highly sophisticated mechanics and difficult to access lumina, as well as the use of non-stainless material mixes. These devices can pose significant challenges for processing and require substantial proficiency and deep technical understanding. The latter are vital for successful processing and must be conveyed by the manufacturer upon purchase and periodically refreshed with users when appropriate. Furthermore, processing technologies and principles, e.g., vaporized hydrogen peroxide as an alternative to classic steam sterilization (also known as autoclavation), and the use of peracetic acid as a sterilant [11] have emerged over the last decades.

Over the last 65 years, significant progress has been made in medical device design, processing technologies and complexity of medical interventions. Furthermore, the emergence of multidrug-resistant microorganisms and new insights to natural microbiomes in different body cavities present additional challenges to the area of Infection Prevention & Control. Thus, it may be advisable to critically assess if an update of the Spaulding classification could provide additional guidance to professional audiences and enhance patient safety. A joint and collaborative initiative of manufacturers of medical/surgical devices and processing technologies, medical doctors, medical device processing experts as well as regulators could ideate the needed renovation, not necessarily a revolution, of the Spaulding Classification – the basic concept of medical device processing based on degree of risks associated with a medical procedure today.

Sources and further readings

  1. G McDonnell, P Burke. Disinfection is it time to reconsider Spaulding. Journal of Hospital Infection 78 (2011). doi:10.1016/j.jhin.2011.05.002. Accessed April 2022.

  2. FDA. https://www.fda.gov/medical-devices/reprocessing-reusable-medical-devices/how-are-reusable-medical-devices-reprocessed. Accessed April 2022.

  3. FDA. https://www.fda.gov/media/80265/download. Accessed April 2022.

  4. ISO. https://www.iso.org/news/ref2570.html. Accessed April 2022.

  5. Earle H. Spaulding, Principles and Application of Chemical Disinfection, AORN Journal, Volume 1, Issue 3, 1963, 36-46,ISSN 0001-2092. https://doi.org/10.1016/S0001-2092(08)70737-3. Accessed April 2022.

  6. CDC. https://www.cdc.gov/oralhealth/infectioncontrol/glossary.htm. Accessed April 2022.

  7. CDC. https://www.cdc.gov/infectioncontrol/guidelines/disinfection/tables/table1.html. Accessed April 2022.

  8. Mainul Haque, et al. Infect Drug Resist. 2018; 11: 2321–2333. Published online 2018 Nov 15. https://doi.org/10.2147/IDR.S177247. Accessed April 2022.

  9. Guest JF, Keating T, Gould D, et al Modelling the annual NHS costs and outcomes attributable to healthcare-associated infections in England. BMJ Open 2020;10:e033367. doi:  https://bmjopen.bmj.com/content/10/1/e033367. Accessed April 2022.

  10. CDC. https://www.cdc.gov/hai/data/portal/covid-impact-hai.html. Accessed April 2022.

  11. CDC, https://www.cdc.gov/infectioncontrol/guidelines/disinfection/sterilization/peracetic-acid.html. Accessed April 2022.