The research team, led by Madison Balagtas and supervised by Ashley E. Levack of the Department of Orthopaedic Surgery and Rehabilitation at Loyola University Medical Center, set out to fill a conspicuous gap in the literature. Previous comparisons of antiseptic solutions had relied largely on static well-plate models and focused on arthroplasty surfaces such as porous titanium, polymethylmethacacrylate cement, cobalt-chromium, and oxidized zirconium. Stainless steel, despite being the most widely used metal in plates, screws, and nails for fracture fixation, had never been directly tested for its susceptibility to antiseptic irrigation. Moreover, static models fail to capture the hydrodynamic conditions that shape biofilm architecture in real wounds, where fluids constantly move and shear forces sculpt the microbial community into structures quite different from those grown in a motionless dish.

To address both shortcomings, the investigators turned to the CDC biofilm reactor, a validated laboratory system that grows reproducible biofilms under continuous flow. Sterile disk-shaped coupons made of 316L stainless steel, ten millimeters in diameter, were mounted in polypropylene holders inside the reactor vessel containing five hundred milliliters of tryptic soy broth. The system was inoculated with methicillin-sensitive S. aureus strain ATCC 49230 at approximately one hundred thousand colony-forming units per milliliter and operated in batch mode for twenty-four hours at thirty-seven degrees Celsius with gentle stirring. It then switched to continuous-flow mode for another forty-eight hours, with dilute medium pumped through the vessel at 6.94 milliliters per minute, delivering roughly twenty liters over the flow phase. By the end of the seventy-two-hour cultivation period, the coupons carried mature, flow-conditioned biofilms that more closely approximate the hydrodynamic environment of a surgical field than any static culture could.

The treatment phase was deliberately simple and clinically grounded. Each biofilm-coated coupon was rinsed gently in phosphate-buffered saline to remove non-adherent planktonic cells, then submerged for exactly three minutes in one of six irrigation solutions: normal saline, ten percent povidone-iodine, 0.35 percent povidone-iodine diluted in saline, a one-to-one mixture of ten percent povidone-iodine with three percent hydrogen peroxide, a commercial hypochlorous acid wound solution, or a 0.05 percent chlorhexidine gluconate lavage. The three-minute dwell time mirrors established orthopedic irrigation protocols and matches the conditions used in prior comparative studies, allowing direct comparison across investigations. Untreated controls and saline groups were included in every experimental run to separate the mechanical effect of rinsing from genuine chemical antibiofilm activity.

Quantifying what survived the treatment required careful biofilm disruption. Coupons were transferred to tubes of fresh medium and subjected to probe sonication at approximately seventeen to eighteen watts, using a manual pulsing rhythm of five seconds on and five seconds off for a cumulative five minutes of active sonication, with samples kept on ice throughout to prevent heat damage. The resulting suspensions were serially diluted, spread-plated onto agar in triplicate, incubated overnight, and counted. The entire protocol, from bacterial culture through colony enumeration, was repeated on four separate dates, with three coupons per treatment per run and three agar plates per coupon, yielding 252 plates across all runs and groups. Statistical analysis employed a mixed-effects negative binomial regression model, an approach well suited to the overdispersed count data typical of biofilm experiments, with experimental date as a fixed effect and culture plate as a random effect, and robust sandwich standard errors to guard against model misspecification.

The results were striking. Every antiseptic solution produced a statistically significant reduction in viable bacteria compared with untreated controls, but the magnitude varied enormously. Ten percent povidone-iodine achieved the greatest effect, a 3.46-log10 reduction equivalent to 99.97 percent killing, leaving only about 2,300 colony-forming units per milliliter against a control burden of nearly 6.8 million. Remarkably, the dilute 0.35 percent formulation performed almost identically, with a 3.42-log10 reduction and 99.96 percent killing. The difference between full-strength and dilute povidone-iodine was a negligible 0.04 logs, and their confidence intervals overlapped substantially. Both concentrations comfortably surpassed the three-log10 reduction threshold widely used as an operational benchmark for bactericidal antibiofilm activity in orthopedic biofilm research.

The remaining solutions trailed behind. The povidone-iodine and hydrogen peroxide mixture achieved a 3.24-log10 reduction, still above the threshold but slightly inferior to povidone-iodine alone, with no evidence of the synergistic enhancement some prior work had suggested. Hypochlorous acid delivered a 2.95-log10 reduction and chlorhexidine gluconate a 2.46-log10 reduction, both exceeding 99 percent killing yet falling short of the three-log benchmark. Chlorhexidine-treated coupons retained roughly tenfold more viable bacteria than the povidone-iodine groups. Normal saline, the default irrigant in many operating rooms, managed only a 0.15-log10 reduction, or about 30 percent, leaving bacterial burdens within the same order of magnitude as untreated controls. In practical terms, for every ten thousand bacteria on an untreated coupon, only three would remain after ten percent povidone-iodine treatment, whereas saline would leave roughly seven thousand behind.

The equivalence of dilute and full-strength povidone-iodine may prove to be the study’s most consequential finding. Surgeons frequently dilute ten percent povidone-iodine out of concern for cytotoxicity to osteoblasts, fibroblasts, and other host cells, since in vitro evidence shows that concentrations of 0.1 percent and above can impair the survival and migration of these cell types. Yet clinical series have not consistently linked intraoperative povidone-iodine irrigation to adverse wound healing. The new data suggest that such dilution may cost little in antibiofilm potency, a reassuring combination of preserved efficacy and reduced tissue toxicity. Mechanistically, povidone-iodine releases free molecular iodine that oxidizes microbial membrane lipids, proteins, and nucleic acids, and dilute formulations may release a higher proportion of free iodine relative to total iodine content, potentially explaining the preserved activity at 0.35 percent. Earlier work by Oduwole and colleagues also showed that even sub-inhibitory povidone-iodine concentrations suppress staphylococcal biofilm formation by downregulating the icaADBC operon, complementing the present findings on established biofilms.

Intriguingly, the results diverge from a 2025 study by Chao and colleagues, who found that 0.35 percent povidone-iodine and 0.05 percent chlorhexidine both failed to achieve a three-log reduction against mature S. aureus biofilms on cobalt-chromium and oxidized zirconium surfaces in a static model. The Loyola team hypothesizes that biofilms grown under continuous flow in the CDC reactor may differ structurally from static well-plate biofilms in ways that improve antiseptic penetration, and that surface material and bacterial strain differences may also contribute. These model-dependent discrepancies underscore why testing across multiple biofilm systems and implant surfaces matters before drawing firm clinical conclusions. Similarly, the absence of synergy in the povidone-iodine and hydrogen peroxide mixture contrasts with a study by Wan and colleagues that applied the two agents sequentially with double the total contact time, highlighting how concentration, sequence, and exposure duration can reshape apparent drug interactions.

The authors are careful to frame their findings within the limits of the model. The experiments used a single organism, methicillin-sensitive S. aureus, whereas chronic implant infections often involve methicillin-resistant strains, coagulase-negative staphylococci, gram-negative bacteria, and polymicrobial communities whose antiseptic susceptibility may differ. Only stainless steel was tested, the static three-minute soak ignores the mechanical forces of pulse lavage that contribute to bacterial debridement in the operating room, colony counting was performed without formal blinding, and cytotoxicity to bone and soft tissue was not assessed. Notably, the Fracture-Related Infection Consensus Group currently recommends low-pressure saline irrigation and does not advise antiseptic additives, citing cytotoxicity concerns. This study does not overturn that guidance, but it adds meaningful in vitro evidence to an ongoing debate, establishing a comparative efficacy baseline on a fracture-fixation-relevant surface and justifying further translational work with multiple species, realistic irrigation workflows, and paired cytotoxicity profiling before antiseptic irrigation practice changes at the bedside.

Subject of Research: Antiseptic irrigation efficacy against Staphylococcus aureus biofilms on stainless steel orthopedic implants

Article Title: In vitro analysis of antiseptic solution effects on Staphylococcus aureus biofilms on orthopedic implant materials

Article References: Balagtas, M., Chrulski, K., Feffer, M., Baldridge, M., & Levack, A. E. (2026). In vitro analysis of antiseptic solution effects on Staphylococcus aureus biofilms on orthopedic implant materials. Journal of Bone and Joint Infection, 11(4), 493-501. https://doi.org/10.5194/jbji-11-493-2026

Image Credits: AI Generated

DOI: 10.5194/jbji-11-493-2026

Keywords: biofilm, Staphylococcus aureus, povidone-iodine, orthopedic implants, stainless steel, antiseptic irrigation, CDC biofilm reactor, chlorhexidine, hypochlorous acid, fracture-related infection, surgical debridement, antibiotic tolerance

The research, published in Food Science and Biotechnology, was conducted by Ji-Yeon Lee, Ju-Hui Lee, Eun-Young Chung, and Sang-Soon Kim across Konkuk University, Dankook University, and the Korea Agro-Fisheries and Food Trade Corporation. Rather than testing disinfection in laboratory beakers, the team evaluated three systems in commercial-scale cold rooms held at 1 plus or minus 0.5 degrees Celsius: hypochlorous acid water applied at concentrations of 50 to 80 parts per million, a dielectric barrier discharge cold plasma system generating roughly 30 parts per billion of ozone, and gaseous chlorine dioxide released in total amounts ranging from 12.96 to 22.68 grams. The choice of technologies is significant because all three are non-thermal, meaning they kill or suppress microorganisms without heat, avoiding the tissue damage that thermal treatments would inflict on delicate leafy vegetables.

Sclerotinia sclerotiorum is a formidable adversary in postharvest systems. The fungus causes Sclerotinia rot, a destructive disease of solanaceous and brassicaceous crops worldwide, and it survives in soil as hardened sclerotia that can germinate and infect stored produce when conditions turn humid and cool. In stored cabbage, infection spreads head to head, and a single decayed leaf can contaminate an entire pallet unit. Traditional control relies heavily on synthetic fungicides or chlorine washes, both of which face increasing regulatory and consumer resistance. This is precisely the gap the Korean team set out to fill, testing whether non-thermal disinfection could suppress the pathogen while preserving the quality attributes that make cabbage suitable for kimchi production.

The first headline finding is encouraging: all three systems suppressed mold growth during the storage trial. To confirm the identity of the spoilage organism, the researchers turned to molecular diagnostics rather than relying solely on visual symptoms. Using real-time polymerase chain reaction, they verified that the mold colonizing the stored cabbage was indeed Sclerotinia sclerotiorum. This matters because accurate pathogen identification underpins every subsequent decision about treatment efficacy. Visual decay can be caused by multiple fungi and bacteria, and misidentification could lead growers and storage operators to deploy the wrong intervention. The molecular confirmation anchors the study’s conclusions in a verifiable biological target.

Among the three technologies, chlorine dioxide emerged as the strongest antifungal agent. This gaseous oxidant has a growing track record in postharvest science; previous studies have shown it controlling green mold in citrus, suppressing postharvest fungi in longan fruit, and extending the freshness of strawberries during export. Its advantage lies in its ability to penetrate air spaces within palletized produce and reach surfaces that liquid sanitizers cannot easily contact. For a leafy, layered vegetable like Napa cabbage, where outer leaves shield inner ones, that gaseous reach is a genuine technical asset. The study’s results add Sclerotinia rot of cabbage to the list of postharvest diseases that chlorine dioxide can meaningfully suppress under realistic storage conditions.

But the story is not one of unqualified triumph, and this is where the research becomes genuinely instructive. Chlorine dioxide treatment came with a measurable cost: heads treated with the gas showed a significantly higher mean weight loss of 9.48 percent during days 79 to 93 of storage, a statistically significant difference at the p less than 0.05 level. The authors attribute this late-storage weight penalty to oxidative degradation of the epicuticular wax, the thin, waxy cuticular layer that coats cabbage leaves and acts as the plant’s primary barrier against water loss. In effect, the same oxidative chemistry that destroys fungal cells also erodes the vegetable’s own waterproofing. Once the wax layer is compromised, water vapor escapes faster, heads lose turgor, and marketable weight drains away. It is a textbook example of a postharvest trade-off between microbial control and physiological preservation.

The cold plasma system revealed a subtler complication. Dielectric barrier discharge plasma generates a cocktail of reactive oxygen and nitrogen species, including ozone at the roughly 30 parts per billion levels measured in this trial. While the plasma suppressed mold, the researchers observed localized reductions in soluble solids, the sugars and dissolved compounds that contribute to flavor and fermentation quality, in cabbage positioned near the device. The team interprets this as a dose-dependent physiological stress response: produce closest to the plasma source experiences the highest reactive species flux, and that oxidative stress appears to draw down the vegetable’s soluble carbohydrate reserves. For kimchi production, soluble solids are not a trivial metric, because the sugars available at fermentation time influence lactic acid bacterial activity and final product character. The finding suggests that plasma systems for whole-pallet cabbage will need careful engineering of dose uniformity, not just raw antimicrobial power.

Hypochlorous acid, the third technology, occupies a middle ground. Electrolyzed water and HOCl treatments have gained popularity as chlorine alternatives because the agent is effective at low concentrations and degrades into benign residues. Applied at 50 to 80 parts per million, it contributed to mold suppression without the dramatic weight loss penalty seen with chlorine dioxide. However, as a liquid or aerosol contact sanitizer, it faces the inherent limitation of any surface-applied treatment on a multilayered head of cabbage: penetration is imperfect, and protected microsites between leaves can harbor surviving inoculum that resurfaces later in storage.

Perhaps the most consequential finding for storage operators is temporal: the efficacy of all three systems declined after day 51 of the 93-day trial. Non-thermal disinfection, in other words, is not a set-and-forget solution for multi-month storage. Residual antimicrobial activity fades, whether because the oxidants dissipate, the released gas is exhausted, or surviving microbes adapt to the residual stress environment, a phenomenon consistent with broader research on microbial adaptations to bactericidal stresses. The authors conclude that integration with controlled atmosphere or modified atmosphere packaging is necessary for extended storage stability. This positions non-thermal disinfection not as a standalone fix but as the first line of a layered defense: an initial microbial knockdown followed by atmospheric modification that slows respiration and suppresses pathogen regrowth for the remainder of the storage period.

The broader context gives this work urgency. South Korea’s government purchases Napa cabbage for market stabilization, and the study was supported by the Korea Agro-Fisheries and Food Trade Corporation as part of a long-term storage demonstration project for government-purchased cabbage, with additional funding from the Korea AeroSpace Administration. As climate assessments continue to document shrinking highland growing capacity, the ability to store spring-harvested cabbage for three months or more becomes a matter of national food security, not merely agricultural convenience. What this study delivers is a realistic, commercial-scale evidence base: chlorine dioxide offers the strongest antifungal punch but demands wax-preserving dose optimization; cold plasma requires spatially uniform dosing to protect soluble solids; hypochlorous acid is a gentler but less penetrating option; and none of them alone can carry cabbage through a full storage season. The future of kimchi’s core ingredient, it turns out, will be engineered through combinations of technologies, calibrated leaf by leaf and day by day.

Subject of Research: Non-thermal disinfection of Sclerotinia sclerotiorum decay in stored Napa cabbage

Article Title: Effects of non-thermal disinfection systems on Sclerotinia sclerotiorum decay and quality attributes of spring-harvested Napa cabbage during long-term storage in South Korea

Article References: Lee, J.-Y., Lee, J.-H., Chung, E.-Y., & Kim, S.-S. (2026). Effects of non-thermal disinfection systems on Sclerotinia sclerotiorum decay and quality attributes of spring-harvested Napa cabbage during long-term storage in South Korea. Food Science and Biotechnology. https://doi.org/10.1007/s10068-026-02288-5

Image Credits: AI Generated

DOI: 10.1007/s10068-026-02288-5

Keywords: Napa cabbage, Sclerotinia sclerotiorum, chlorine dioxide, cold plasma, hypochlorous acid, postharvest quality, non-thermal disinfection, kimchi, food storage, climate change, real-time PCR, South Korea