Inclusion Criteria:  Adult patients ≥65years of age American Society of Anesthesiologists (ASA) physical status 2-4 Elective or expedited non-cardiac surgery of at least 2 hours dura- tion under general anaesthesia Requiring a hospital stay of at least one postoperative night A surgical skin incision >5 cm in length or multiple incisions with a total incision length of >5 cm  Exclusion Criteria:·  Poorly controlled diabetes (HbA1c>9.0%) Endovascular procedure with a small (<5 cm length) skin incision Ophthalmic surgery Planned dexamethasone (or other corticosteroid) therapy (eg, history of intractable PONV, maxillofacial surgery, intracranial neurosurgery) Recent (<2 weeks since end of treatment) infective episode requir- ing treatment with antibiotics Chronic antibiotic therapy (eg, for bronchiectasis, cystic fibrosis etc)