Study to determine the efficacy, safety and tolerability of two concentrations of XF-73 nasal gel in combination with body and face washing with chlorhexidine gluconate cloths in eradicating nasal carriage of Staphylococcus aureus.

Inclusion Criteria:

1. Normal, healthy male or female subjects aged between 18 and 75 years.
2. Subjects confirmed to be persistent nasal SA carriers, defined by 3 separate, SA positive cultures from nasal swabs. Two positive cultures should be obtained at screening visits up to 12 weeks prior to inclusion and at least two weeks apart. The final confirmatory culture should be obtained from a nasal swab on the day of admission to the unit (day -1). Note: Dosing with XF-73 may commence before the result of the day -1 swab is obtained. If the result is negative, the subject should be withdrawn.
3. Subjects who are able and willing to provide written informed consent to participate in the study
4. Subjects who have a body mass index (BMI) ≥18.5 kg/m2 and ≤ 32kg/m2.
5. Subjects who agree not to take part in another clinical trial at any time during the study period.

Exclusion Criteria:

1. Female subjects who are or may be pregnant or who are lactating.
2. Subjects who have any acute or chronic illness or infection.
3. Subjects who have smoked within the 3 months prior to screening.
4. Subjects who are females of child-bearing potential, defined as being physiologically capable of becoming pregnant, UNLESS using one or more of the following acceptable methods of contraception; established use of oral, injected or implanted hormonal contraception, intrauterine Device (IUD or Coil AND barrier Method (condom or diaphragm or cervical/vault cap) plus spermicidal cream/gel. Contraceptive use should continue throughout the study and for 1 month following completion of the study.
5. Subjects who are fertile males, defined as all males physiologically capable of conceiving offspring, UNLESS the subject agrees to comply with acceptable contraception e.g. condom plus spermicidal cream/gel. Contraceptive use should continue throughout the study and for 3 months following completion of the study.
6. Subject with any open wound, lesion, inflammation, erythema or infection affecting the nostrils, nose, upper lip and area of skin close to the nose. This includes herpes simplex lesions and discoid lupus.
7. Subjects who have a currently symptomatic upper respiratory tract infection, nasopharyngitis, influenza or condition involving increase in nasal secretion such as seasonal or chronic, allergic rhinitis.
8. Subjects with a history of drug or alcohol abuse in the previous 12 months or who have a positive urine drug test for substances of abuse.
9. Subjects with a known clinically significant history of atopy or hypersensitivity to any drug or latex.
10. Subjects with a history of serious illness, cancer or psychiatric condition.
11. Subjects with known skin photosensitivity.
12. Subjects with a personal or family history of porphyria.
13. Subjects who have been treated with or have taken any prescribed or over-the-counter medication within the 14 days prior to admission, with the exception of hormonal contraceptives or hormone replacement therapy.
14. Subjects who have taken or used topical or systemic antibiotics within the month prior to screening.
15. Subjects who are known to have serum hepatitis, or who are carriers of the hepatitis B surface antigen (HBsAg) or hepatitis C antibody, or who have a positive result to the test for human immunodeficiency virus (HIV) antibodies
16. Subjects who have participated in a clinical trial within the last 3 months.
17. Subjects who have been exposed to XF-73 as part of a previous clinical trial.
18. Subjects with any clinically significant abnormality in vital signs or laboratory analyses at screening or at baseline, based on the opinion of the investigator.
19. Subjects with nasal polyps or significant anatomical nasal abnormality.
20. Subjects with a history of nasal surgery, including cauterization in the last 12 months.
21. Subjects with a history of multiple episodes [>3] of epistaxis within the last 12 months.
22. Subjects known to have dermal sensitivity to benzalkonium chloride or other quaternary ammonium disinfectants.
23. Subjects with in-situ nasal jewellery or open nasal piercings.
24. Subjects known to have dermal sensitivity to chlorhexidine gluconate (CHG).
25. Subjects with a history of abnormal bleeding, bruising, frequent nosebleeds or a diagnosis of von Willebrand disease.
26. Subjects who have or have had an autoimmune disease.