Assessing the Efficacy of Photodynamic Therapy for Preventing Surgical Site Infections

Two two-minute cycles will be provided by a member of the research team in the pre-operative area on the day of surgery. A saturated swab containing 0.01% methylene blue and 0.25% chlorhexidine gluconate will be applied to nares, which is then activated by light.

Nares will be swabbed with Photosensitizer formulation (0.01% methylene blue with 0.25% chlorhexidine solution). Nasal swab cultures will be obtained before control swabbing and converted to colony-forming units to measure bacterial burden at baseline, and after treatment (2 weeks +/- 7 days). Sinonasal mucosal inflammation using the Flexible Nasendoscopy Endoscopic LK Score will also be obtained before treatment at 2 weeks (+/-7 days).

All patients will receive standard post-operative wound follow up. This might include being advised to contact the GP or the hospital if there are any wound problems and, or, being invited to an out-patient clinic appointment.

Nasal swab cultures will be obtained before Nasal PDT or control swabbing and converted to colony-forming units to measure bacterial burden at baseline, and after treatment (2 weeks +/- 7 days).

Sinonasal mucosal inflammation using the Flexible Nasendoscopy Endoscopic Lund-Kennedy (LK) Score will also be obtained before Nasal PDT or control swabbing and at 2 weeks (+/-7 days).

On Week 2 (±7 days), the participant will undergo an in-person review conducted in the ENT Outpatient department, 2nd floor Southwark wing, Guy's Hospital by the CI, PI or Co-investigator. During this appointment, concomitant medications and use of post-operative antibiotics will be reviewed.

On day 30, the research nurse will telephone participants from the ENT research office. * Review of adverse events/adverse device effects * Review of concomitant medications * Signs and symptoms post-surgery * Nasal washout * Record any use of post-operative antibiotics, both local and systemic