Introduction
Intranasal photodynamic disinfection therapy (PDT) is an emerging nonantibiotic broad-spectrum antimicrobial technology, in which light energy is used to activate a photoactive agent to kill microbial cells in the anterior nares.Reference Septimus and Schweizer1 This strategy has been shown to eliminate intranasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus, with sustained decoloniation for up to 5 days. Approximately one-third of the general population carries S. aureus or its resistant form, MRSA.
The National Institute for Health and Care Excellence (NICE), UK defines a surgical site infection (SSI) as a type of healthcare-associated infection in which a surgical incision site becomes infected after a surgical procedure (NICE, 2013). The occurrence of SSI represents a major health care burden accounting for one in seven hospital-acquired infections in the UK.Reference Totty, Moss, Barker, Mealing, Posnett and Chetter2 SSIs generate costs to the National Health Service (NHS),Reference Tanner, Khan, Aplin, Ball, Thomas and Bankart3 with an estimated total annual cost of over £700 million.
Staphylococcus aureus is a bacterium responsible for a significant proportion of hospital acquired infections.Reference Hindy, Quintero-Martinez, Lee, Scott, Gerberi and Mahmood4 Methicillin (or multi-drug) -resistant S. aureus (MRSA) is a major concern for health systems because of its antimicrobial resistance, making infection with this micro—-organism challenging to treat. Infections caused by MRSA exhibit high mortality, particularly if the bacteria reach the bloodstream.Reference Duerden, Fry, Johnson and Wilcox5 Nasal colonisation with S. aureus increases the overall risk of SSI, including SSI caused by MRSA.Reference Ning, Wang, Zhang and Sha6
Nasal decoloniation is now a key strategy in reducing surgical site infections. In 2020, NICE UK updated a previous guideline to recommend pre-surgical nasal decolonisation in England and Wales.7 The standard of nasal decoloniation care recommended by NICE is a topical ointment containing the antibiotic mupirocin in combination with chlorhexidine body wash before surgery. No photodisinfection approaches were considered by NICE for the 2020 guideline as the technology was not then available. Predictably, emerging strains of S. aureus have resistance to mupirocin.Reference Dadashi, Hajikhani, Darban-Sarokhalil, van Belkum and Goudarzi8
Steriwave® is an emerging medical device delivering a non-antibiotic, broad-spectrum nasal decolonisation via photodisinfection to prevent SSIs. It provides a simple, rapid and painless method of nasal decolonisation. Compared to antibiotic-based alternatives, Steriwave® is administered immediately prior to surgery thus enabling optimal compliance, eliminates the need for screening, is non-resistance forming and thus appropriate for emergency cases and repeat use.
Endoscopic anterior skull base surgery is classed as clean contaminated, with meningitis risk heightened by dural opening and cerebrospinal fluid (CSF) leak. Meningitis poses a significant risk to the patient and results in prolonged hospital stays. Lai et al.Reference Lai, Trooboff, Morgan and Harvey9 conducted a systematic review of meningitis following endoscopic endonasal skull base surgery. The overall rate of post-operative meningitis (amongst a total of 2005 patients) was 1.8 per cent. However, the risk of meningitis in those patients with post-operative CSF leak was 13.0 per cent.
This study aimed to evaluate whether implementation of a clinician-delivered nasal photodisinfection protocol reduces post-operative infectious complications in patients undergoing endoscopic anterior skull base surgery.
Materials and methods
Study design and population
This study was conducted as a before-and-after single-centre service evaluation at a tertiary hospital, registered ref no LOC1989. Outcomes were compared between a control cohort managed with standard pre-operative home-based antibiotic decolonisation and a prospective cohort managed with an added clinician-led nasal photodisinfection protocol. The standard cohort included consecutive adult patients undergoing elective endoscopic anterior skull base surgery with skull base reconstruction using a nasoseptal pedicled flap between July 2022 and June 2024. The prospective cohort included consecutive adult patients undergoing the same procedures from August 2024 to March 2026 following implementation of the photodisinfection protocol. Emergency cases and patients under 18 years of age were excluded.
Intervention
Patients in the intervention group received a single clinician-led nasal photodisinfection treatment immediately prior to surgery using the Steriwave™ system (Ondine Biomedical, Vancouver, Canada. The protocol consisted of application of a 0.01 per cent methylene blue photosensitiser solution to the anterior nares for 30 seconds, followed by illumination with a non-thermal red light at a wavelength of 665 nm for 2 minutes. The photosensitiser was then reapplied and a second 2-minute illumination cycle completed (NHS Supply Chain Innovation Brief 2025: Steriwave Nasal Photodisinfection)
Peri-operative care
All patients in both cohorts underwent surgery performed by the same experienced skull base surgical team, without change in operative technique or reconstructive approach during the study period.Reference Nix, Tyagi and Phillips10, Reference Hughes, Phillips, Tyagi, Sheikh, Sethi and Nix11 Both cohorts received the same single-dose peri-operative intravenous antibiotic prophylaxis, intravenous (iv) Augmentin or Teicoplanin and Gentamicin in penicillin-allergic patients. No patients were prescribed post-operative prophylactic antibiotics. No changes in post-operative care pathways, including saline irrigation and steroid protocol, discharge criteria and follow-up intensity, were changed between the groups.
Outcomes
The primary outcome was surgical site infection within 30 days of the index procedure. SSIs were defined according to institutional criteria and included any clinically diagnosed infection at the surgical site requiring antibiotic therapy. Outcome data were obtained from electronic hospital records, General Practitioner records and structured telephone conducted every 2 weeks following patient discharge until routine ENT follow-up involving nasal endoscopy.
The diagnosis of sinusitis was based upon clinical symptoms plus or minus endoscopic visualisation and the prescription of an antibiotic. Inclusion of community-treated infections may overestimate true SSI but reflects real-world antibiotic utilisation rather than microbiologically confirmed infection alone.
The secondary outcome was the occurrence of post-operative meningitis and ENT out-patient visits required to clean/decrust the nose.
The diagnosis of meningitis was based upon a lumbar puncture and CSF analysis or a strong clinical suspicion of meningitis requiring intravenous antibiotics.
Statistical analysis
Categorical outcomes were compared using Fisher’s exact test owing to event frequency and distribution. Statistical significance was defined as p less than 0.05. Patient-level risk factors including smoking status, diabetes, body mass index (BMI) and operative duration were not extracted from the electronic patient record and were not adjusted for.
A power calculation was performed to aid interpretation of the available sample size. For the primary outcome of 30-day SSI, assuming a reduction from 15 per cent in the standard decolonisation group to 4 per cent following nasal photodisinfection, approximately 105 patients per group would be required to achieve 80 per cent power using a two-sample comparison of proportions with a two-sided α of 0.05. For the secondary outcome of post-operative meningitis, assuming a reduction from 4.8 to 0 per cent, approximately 81 patients per group would be needed.
Results
A total of 200 patients were included in the analysis: 105 patients in the standard decolonisation cohort and 95 patients in the photodisinfection cohort. All patients were included in the outcome analysis with baseline characteristics including pathology and intra-operative CSF leaks similar between the two cohorts, summarised in Table 1.
Baseline characteristics of patients undergoing anterior skull base surgery
CSF = cerebrospinal fluid.
All patients in both arms of the study underwent an endoscopic endonasal approach to the anterior skull base comprising a posterior septectomy, resection of sphenoid face opening of dura and a nasoseptal flap for reconstruction of the skull base defect. All patients received a single-dose, single-agent antibiotic at the time of induction, typically Augmentin.Reference Hughes, Phillips, Tyagi, Sheikh, Sethi and Nix11 No patients in either group were given post-operative prophylactic antibiotics. Surgical procedures included resection of pituitary lesions, craniopharyngiomas, chordomas and meningiomas. Follow up data were available for all patients.
Compliance with nasal photodisinfection was 100 per cent in the intervention cohort. Compliance with home-based decolonisation in the historic cohort was not objectively measured and represents a source of bias but is a real-world reflection.
Primary outcome: surgical site infection
SSI occurred in 15 of 105 patients (14.6 per cent) in the traditional cohort compared with three of 95 patients (3.2 per cent) in the photodisinfection cohort. This represented an absolute risk reduction of 11.4 per cent (95 per cent CI: 3.7 per cent to 19.1 per cent), a relative risk reduction of 78 per cent, with the number needed to treat of nine (95 per cent CI: 5 to 27) Table 2.
Post-operative infectious outcomes within 30 days
Note: Surgical site infection defined as clinically diagnosed infection requiring antibiotic therapy. Individual infections are subcategories of total surgical site infection.
* Fisher’s exact test.
The diagnosis of the 18 SSIs was documented by an ENT consultant in 12 cases and by a General Practitioner in six cases. Comparison using Fisher’s exact test proved a statistically significant association between photo disinfection and reduced SSI (p = 0.0059, two-tailed).
Secondary outcome: post-operative meningitis
Post-operative meningitis occurred in five of 105 patients (4.8 per cent) in the standard cohort and in 0 of 95 patients (0 per cent) in the photo disinfection cohort. Fisher’s exact testing yielded a two-tailed p-value of 0.060, with a corresponding one-tailed p-value of 0.030 based on a pre-specified hypothesis that photodisinfection reduces post-operative meningitis rates.
Among the five patients who developed meningitis, two required endonasal surgical repairs due to a post-operative CSF leak. Mean additional hospital or critical care bed usage was 15 days (range, 10–17 days) for patients developing meningitis (Table 3).
Post-operative healthcare utilisation
No adverse events related to the photodisinfection procedure were reported, and patient feedback about the intervention was uniformly positive.
Discussion
Nasal photodisinfection is an established technique in selective healthcare systems, particularly in Canada.Reference Bryce, Wong, Forrester, Masri, Jeske and Barr12 Its evaluation in anterior skull base surgery, however, needs to be established. This single-centre, before-and-after service evaluation demonstrates that implementation of a nasal photodisinfection protocol was associated with a significant reduction in surgical site infection following anterior skull base surgery. This observational design allows detection of association but cannot establish causality. SSI was selected as the primary outcome due to its frequency and clinical impact and an intentionally pragmatic definition incorporating hospital and community-treated infections was adopted to reflect real-world antibiotic use.
Prevention of SSIs relies on cost-effective infection prevention and control programmes.Reference Dick, Perencevich, Pogorzelska-Maziarz, Zwanziger, Larson and Stone13 However, many infection-prevention and control programmes rely on poorly adhered-to behavioural interventions, and more effective interventions are needed.Reference Makhni, Umscheid, Soo, Chu, Bartlett and Landon14 The primary method for nasal decolonisation in the UK is an antibiotic ointment called mupirocin. Such a strategy has a few issues in particular: (1) Mupirocin only targets bacterial pathogens. (2) Patients must apply the drug nasally twice daily for 5 days; full adherence to the treatment regimen has been documented to be approximately only 39 per centReference Schweizer, Chiang, Septimus, Moody, Braun and Hafner15. (3) An important and globally significant concern with widespread use of mupirocin is the development of antimicrobial resistanceReference Khoshnood, Heidary, Asadi, Soleimani, Motahar and Savari16; mupirocin resistance has already been documented in the UK Carriage study which represents the largest study to date characterising the human nasal microbiome from over 100 samples.Reference Aggarwal, Bellis, Blane, de Goffau, Wagner and DYK17 (4) This 5-day mupirocin pre-operative regimen is not suitable for emergency cases due to the time course.
Nasal photodisinfection offers a number of potential advantages over traditional antibiotic-based decolonisation: (1) Photodynamic antimicrobial therapy has been shown to reduce nasal microbial burden, including S aureus and MRSA, and appears not to disrupt mucosal integrity or the nasal microbiome.Reference Aroso, Schaberle, Arnaut and Pereira18 (2) This non-antibiotic mechanism may be particularly attractive in the context of increasing mupirocin resistance and antimicrobial stewardship considerations19; In addition, it is broad spectrum across all microbes, repeatable and does not introduce resistance.Reference Pedigo, Gibbs, Scott and Street20 (3) Photodisinfection is quick to administer, immediate in effect and so suitable for emergency cases that cannot wait for the standard 5-day regime; the observed effect may be related to the immediate reduction in sinonasal microbial burden at the operative field, which is particularly relevant in extended endonasal approaches.
Bacteria associated with many post-operative surgical site infections have been shown to live in the patient’s nose, particularly in the anterior nares.Reference Wertheim, Melles, Vos, Van Leeuwen, Van Belkum and Verbrugh21 Anterior skull base surgery presents a unique risk profile for infection because of trans nasal access, extended operative duration and proximity to sinonasal bacterial reservoirs.Reference Lai, Trooboff, Morgan and Harvey9
At a cost of approximately £86 per patient, photodisinfection compares favourably with the substantial costs associated with SSI and post-operative meningitis, including prolonged hospitalisation and critical care utilisation. With a relative risk reduction of 78 per cent, the number needed to treat would be nine patients; this equates to an approximate cost of £774 per SSI prevented.
The reduction in post-operative ENT visits may reflect improved early healing or reduced crusting, potentially related to a more balanced post-operative nasal microbiome. It was hypothesised that nasal Steriwave® decontamination prior to surgery may reduce the amount of nasal crusting during the healing period. The large-scale Carriage study suggests that the nose has a protective microbiome consisting of many types of bacteria that serve as a natural barrier to bacterial over-colonisation, especially inhibiting S. aureus.Reference Aggarwal, Bellis, Blane, de Goffau, Wagner and DYK17 Traditional topical antibiotics like mupirocin can cause prolonged microbial imbalance, eradicating these protective commensals allows resistant pathogens, such as S. aureus, to repopulate more aggressively. Steriwave® photodisinfection is potentially a microbiome-friendly method which resets the nasal microbiome without the selective pressure of chemical antibiotics. If Steriwave® resets the microbiome, the native protective flora will act as a natural biological barrier to pathogen overgrowth in the healing nasal cavity. This may result in a reduction in the number of post-operative ENT out-patient department staff required to debride the post-operative nasal corridor, with a cost saving for the hospital. Indeed, between the groups the average number of visits in the control cohort of 1.34 is seen to significantly reduce to 1.08 in the Steriwave® group.
Strengths of the study
Strengths include complete compliance with the intervention, and integration of the protocol into routine clinical workflow without added procedural complexity. Outcome data were available on all cases and obtained from multiple sources, to reflect real-world usage of post-operative antibiotics by the operative team, the General Practitioner and any surrounding secondary care such as local hospitals.
The skull base team has utilised the endonasal endoscopic approach to the anterior skull base since 2008 the operative technique utilised in both cohorts firmly established.Reference Nix, Tyagi and Phillips10 Antibiotic prophylaxis protocols were identical between the two groups using a single pre-operative intravenous dose with no post-operative prophylactic antibiotics prescribed. Significantly, the two cohort groups have a similar pathology make-up with approximately 77 per cent of cases in each group having pituitary-based pathologies and 37 per cent requiring intra-operative repair of a CSF leak. Consequently, the main difference between the two groups in this study is the addition of the Steriwave® therapy.
Limitations of the study
The study has limitations. Its observational design precludes definitive causal inference, and unmeasured confounders may have influenced outcomes. The use of historic controls introduces the potential for temporal bias; however, surgical technique, reconstructive strategy, peri-operative antibiotic protocols, the operating team and post-operative care remained constant throughout the study period. The observed effect may partially reflect the difference between clinician-delivered and patient-dependent interventions, rather than the antimicrobial mechanism alone. The pragmatic SSI definition, with the reliance on antibiotic prescription as an outcome measure, risks misclassification with empirical treatment of post-operative crusting or inflammation as opposed to infection. This would be particularly relevant to six infections diagnosed by General Practitioners and not confirmed by ENT endonasal review; however, it will represent real-world antibiotic prescription practice. Surgical site risk factors such as smoking, diabetes, BMI and operative duration were not collected and may bias results, but a significantly larger cohort would be needed for analysis of all potential confounding variables.
Future directions
Endoscopic anterior skull base surgery is a fundamentally rhinology-led approach. A randomised rhinology procedure-based trial would be the next step to establishing Steriwave® providing more definitive evidence regarding efficacy, cost-effectiveness and the potential role of Steriwave® in routine rhinology practice.
Steriwave® technology has so far been directed at patients. As we have a treatment such as Steriwave® that is repeatable and does not induce antibiotic resistance then why not introduce this to the surgical scrub team as well.Reference Troeman and Kluytmans22, Reference Jaichenco and Lima23 The nationwide rate of S. aureus nasal carriage among surgeons proved to be significantly greater compared with a non-hospitalied patient control group (45 per cent vs. 30 per cent).Reference Van Vugt, Coelen, Van Dam, Winkens, Derikx and Heddema24
• Nasal decontamination is recommended to reduce surgical site infections
• Standard nasal decolonisation with mupirocin recommended by National Institute for Health and Care Excellence (NICE) is limited by poor compliance and rising antimicrobial resistance
• Steriwave® is a non-antibiotic broad spectrum antimicrobial technology utilising photodisinfection to immediately destroy pathogens
• Steriwave® significantly reduces surgical site infections from 14.6 to 3.7 per cent following its application in patients undergoing endoscopic anterior skull base surgery
• Steriwave® is a potential shift away from such established strategies that will eventually create resistance
• Given its rapid action, excellent compliance and lack or resistance potential, Steriwave® represents a compelling alternative to mupirocin-based decolonisation and should be considered for routine adoption
Conclusion
Utilisation of Steriwave® photodisinfection is a potential shift away from such established strategies that will eventually create resistance. Steriwave® significantly reduces SSI, antibiotic usage and ENT out-patient burden following endoscopic anterior skull base surgery.
Acknowledgement
Leeds Charities for funding Capital cost of Steriwave machine £7500.
Competing interests
None.
