What do the sterilization and sterility assurance fields have in common with a Clint Eastwood movie? Right now, the fields have “a lot of good, some bad, and some ugly.”
That’s according to Dr. William Rutala, director of the Statewide Program for Infection Control and Epidemiology and professor of medicine at the University of North Carolina. At the 2025 edition of the KILMER conference, Rutala took a wide-lens view of his field. Drawing on his decades of experience and more than 700 scientific publications, he discussed new sterilization technologies, surface disinfection, endoscope sterilization, ethylene oxide, and more.
The Good: Where Sterilization Science Succeeds
Rutala believes the field has “much better guidelines than we did many years ago.” Not only have groups like AORN and AAMI increasingly produced useful guidance documents, but guidelines from agencies like the FDA have also evolved. Yet implementing manufacturer instructions for use (IFUs) remains challenging.
Right now, surgical instruments receive a Spaulding classification of “critical.” Overall, infections are rare, as surgical instruments have an enormous margin of safety. About 90% of reusable medical devices are sterilized using steam, and heat-resistant devices are usually processed using ethylene oxide (EO), vaporized hydrogen peroxide (VHP), and hydrogen peroxide gas plasma (HPGP).
Rutala also touted the importance of studies that “assess the robustness of sterilization technologies.” He cited several that focused on how proteins and salts impact sterilization. For example, one study of “dirty or non-cleaned instruments” applied steam, EO, and HPGP to instruments contaminated with bacteria and dried blood. Researchers found that steam was by far the most effective, followed by EO and HPGP.
Monitoring capabilities for physical, chemical, and biological parameters have also improved dramatically. Since the 1970s, the “read-out time” for assessing biological indicators has been reduced from days to minutes.
Environmental contamination and controls also belong in the “good” category. But despite awareness that environmental factors lead to healthcare-associated infections (HAIs), “we know our rooms are not adequately cleaned.” The issue? The field has “excellent products” but “very poor practices.” Further, “there are no specific regulations or professional organizational guidelines for microbiological control of surfaces.”
For instance, low-level disinfectants are “very effective against bacteria.” Yet the next patient in the room may be infected if pathogens are not removed from nearby surfaces. In response to these risks, “we have implemented supplemental disinfection technologies,” including the no-touch approach to room decontamination. Continuous room decontamination technologies, such as Far UV-C light paired with motion detectors, show promise but require more study.
The Bad: Room for Improvement
Rutala placed three items in the “bad” category. First, until November of 2024, no FDA-cleared standard defined when an instrument was clean. Previously, cleanliness was usually defined visually. According to Rutala, there should be a standard to address circumstances where sterilization fails. “We just shouldn’t have best available technology; we should have some standard that relates to the failure of our sterilization technology.” According to Rutala, a cleaning verification test should be, at a minimum, easy to perform, rapid, robust, accurate, safe for equipment, and evidence-based.
Second, there is no standardized test that measures the effectiveness of disinfection and sterilization technology against prions. Creutzfeldt-Jakob Disease (CJD), the most common form of prion disease in the U.S., can incubate for years and has a relatively rapid onset. Worse, these prions are resistant to disinfection and sterilization, strengthening the need for a standardized test. There are already two definitive cases where a medical instrument was responsible for a CJD infection.
Finally, there are no FDA-cleared sterilization technologies for use against prions. Rutala noted that existing guidelines on this issue can be controversial, as they are not based on standardized testing and prionicidal data.
The Ugly: What Harms Patients
Issues with endoscopes are the bulk of the “ugly,” or “the very, very bad.” Per Rutala, endoscopes “always should have been … considered a critical instrument requiring sterilization” because of their complexity and high microbial load.
The transition to considering endoscopes as critical instruments has been gradual. In 2014, an article in JAMA recommended moving from disinfection to sterilization, and AAMI and AORN followed suit. Now, we have “FDA-cleared technologies for reprocessing useable endoscopes,” including sterilization modalities such as EO and HPGP.
A Word on Ethylene Oxide
Last, Rutala addressed ethylene oxide and concerns over “its role in public health and the fragility of the medical device supply chain.” Many medical devices would not be usable without it, and implementing the 2024 EPA rule could disrupt the supply chain. Public commitments to modality switching are “easy to say,” but implementation is a very complex problem. So far, the transition from ethylene oxide to other sterilization technologies has been slow. In 2024, the Global Unique Device Identification Database (GUDID) indicated that the FDA had cleared nearly 56,000 individual medical devices for sterilization via EO. Potential alternatives lagged far behind.
The Future
The good, the bad, and the ugly can tell us a lot about hospital sterilization as well as industrial sterilization. Rutala’s keynote at the 2025 KILMER conference set the stage for the rest of the conference’s programming. Despite clear optimism about the field’s advancements, he did not shy away from enduring threats to patients. Speaking for sterilization scientists and professionals, he concluded his address to the medical device industry professionals in the room, saying, “we essentially have many of the same issues you do.”
Those interested in the slides from the keynote can access them at disinfectionandsterilization.org.
